Federal Motor Vehicle Safety Standards; Bus Rollover Structural Integrity

DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Part 571

[Docket No. NHTSA-2021-0088]

RIN 2127-AK96

Federal Motor Vehicle Safety Standards; Bus Rollover Structural Integrity

AGENCY:

National Highway Traffic Safety Administration (NHTSA), Department of Transportation (DOT).

ACTION:

Final rule.

SUMMARY:

NHTSA is issuing this final rule to establish Federal Motor Vehicle Safety Standard (FMVSS) No. 227, “Bus rollover structural integrity,” to enhance the rollover structural integrity of over-the-road buses (motorcoaches), and other buses with a gross vehicle weight rating (GVWR) greater than 11,793 kilograms (kg) (26,000 pounds (lb)). This final rule, issued pursuant to the Moving Ahead for Progress in the 21st Century Act (MAP-21), requires the buses to provide a “survival space” in a rollover test to protect occupants from possible collapse of the bus structure around them. In addition, to reduce the likelihood of ejection, this final rule prohibits emergency exits from opening in the rollover test. This final rule ensures that bus roofs and side wall panels will resist deformation and intrusion into the occupant space in rollover crashes, and reduces the risk of emergency exits becoming ejection portals in a crash.

DATES:

The effective date of this final rule is: December 30, 2024. Optional early compliance is permitted.

Petitions for reconsideration:

Petitions for reconsideration of this final rule must be received not later than February 14, 2022.

ADDRESSES:

Petitions for reconsideration of this final rule must refer to the docket number set forth above and be submitted to the Administrator, National Highway Traffic Safety Administration, 1200 New Jersey Avenue SE, Washington, DC 20590. Note that all petitions received will be posted without change to

https://www.regulations.gov

, including any personal information provided.

Privacy Act:

Please see the Privacy Act heading under Rulemaking Analyses and Notices.

FOR FURTHER INFORMATION CONTACT:

For non-legal issues, you may contact James Myers, NHTSA Office of Crashworthiness Standards, telephone 202-493-0031, fax 202-493-2990. For legal issues: Deirdre Fujita, NHTSA Office of Chief Counsel, telephone 202-366-2992, fax 202-366-3820. Address: National Highway Traffic Safety Administration, U.S. Department of Transportation, 1200 New Jersey Avenue SE, West Building, Washington, DC 20590.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Executive Summary

a. Introduction

b. How This Final Rule Differs From the Notice of Proposed Rulemaking

c. NTSB Recommendations

d. Costs and Benefits

e. NHTSA's Determination of MAP-21 Requirements and Considerations

f. Retrofitting

II. Introduction

III. NHTSA's Statutory Authority

a. National Traffic and Motor Vehicle Safety Act (Safety Act)

b. MAP-21 (The Motorcoach Enhanced Safety Act of 2012)

IV. Safety Need (FARS 2004-2018 Data Analysis)

V. Summary of the NPRM

VI. High Level Summary of the Comments

VII. Scope and Purpose of the Rule

VIII. Applicability of the Rule

a. Medium-Size Buses (Buses With a GVWR of 4,536 to 11,793 kg (10,000-26,000 lb))

b. Large Buses

IX. School Bus Derivative Buses

X. Performance Requirements

a. Severity of the Rollover Test

b. Intrusion Into the Survival Space

c. Luggage Racks and Seat Anchorages

d. Emergency Exits

XI. Glazing Issues

a. Side Glazing on the Non-Struck Side of the Bus

b. Type of Glazing

c. Moon Roofs

d. Struck-Side Window Evaluations

XII. Test Procedure Issues

a. Ballasting the Vehicle

b. Vehicle Fluids

c. Additional Tools for Survival Space Evaluation During Testing

XIII. Other Issues

a. ECE R.66 Alternative Compliance Methods

b. Regulatory Alternatives

1. FMVSS No. 216

2. FMVSS No. 220

c. Additional MAP-21 Considerations

XIV. Lead Time

XV. Retrofitting Used Buses

XVI. Overview of Costs and Benefits

XVII. Rulemaking Analyses and Notices

I. Executive Summary

a. Introduction

This final rule substantially improves motorcoach safety. It establishes an FMVSS to improve the resistance of motorcoach roofs and side wall panels to deformation and intrusion into the occupant compartment in rollover crashes, and fulfills a mandate in section 32703(b)(1) of MAP-21. This final rule also accords with section 32703(b)(2) of MAP-21 by requiring emergency exits to remain closed in a rollover to prevent partial and complete ejection of passengers.

This final rule achieves longstanding NHTSA and Departmental goals to enhance motorcoach safety. NHTSA identified four priority areas in which to improve the safety of motorcoaches and other large buses: Requiring passenger seat belts, improved rollover structural integrity, improved emergency evacuation, and fire safety.

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With this final rule, NHTSA has completed research and rulemaking on the first two priority areas and completed research on the other two.

1

See

“NHTSA's Approach to Motorcoach Safety,” Docket No. NHTSA-2007-28793. In NHTSA's plan, “motorcoach” referred to inter-city transport buses. In 2009, DOT also issued a Motorcoach Safety Action Plan that addressed additional factors, such as driver fatigue and operator maintenance schedules. An update to the Departmental plan was issued in December 2012,

https://www.fmcsa.dot.gov/sites/fmcsa.dot.gov/files/docs/Motorcoach-Safety-Action-Plan-2012.pdf

. This final rule is an action included in the Departmental plan.

Congress also focused on these and other areas in incorporating the Motorcoach Enhanced Safety Act of 2012 into MAP-21 (Pub. L. 112-141). Among other matters, MAP-21 directed NHTSA (as delegated by the Secretary of Transportation) to require seat belts in “motorcoaches,” a term, Congress stated, that has the same meaning given the term “over-the-road bus” in section 3038(a)(3) of the Transportation Equity Act for the 21st Century (49 U.S.C. 5310 note). An over-the-road bus (OTRB) is a bus characterized by an elevated passenger deck located over a baggage compartment.

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NHTSA has used the term “over-the-road bus” in the FMVSSs issued pursuant to the MAP-21 mandates. For example, NHTSA fulfilled MAP-21's seat belt mandate by amending FMVSS No. 208, “Occupant crash protection,” to require seat belts in each passenger seating position in OTRBs, as well as in other buses that are not OTRBs (non-OTRBs) with a GVWR greater than 11,793 kg (26,000 lb).

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(For the convenience of the reader, NHTSA uses the term “large buses” in this final rule to refer to OTRBs regardless of GVWR and non-OTRBs with a GVWR

greater than 11,793 kg (26,000 lb), with some exceptions.)

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Under section 32701(6) of the Motorcoach Enhanced Safety Act, “motorcoach” does not include a bus used in public transportation provided by, or on behalf of, a public transportation agency, or a school bus.

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78 FR 70416, November 25, 2013; denial of petitions for reconsideration, 81 FR 19902, April 6, 2016.

Section 32703(b)(1) of MAP-21 also directed NHTSA to pursue rulemaking for OTRBs to establish improved roof and roof support standards that substantially improve the resistance of bus roofs to deformation and intrusion in rollovers. MAP-21 requires NHTSA to adopt a final rule if NHTSA determines that such standards meet the requirements and considerations in subsections (a) and (b) of section 30111 of the National Traffic and Motor Vehicle Safety Act.

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As discussed in this final rule, NHTSA has made such a determination regarding an FMVSS for all large buses.

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MAP-21, section 32703(b) and (b)(1)).

This final rule complements the November 2013 seat belt rule. With all new large buses manufactured since 2016 required to have lap and shoulder seat belts for passengers, increasing numbers of passengers can be belted. This final rule establishing FMVSS No. 227 will ensure that these belted passengers will be significantly protected against unreasonable risk of injury in frontal crashes and significantly protected against the risk of ejection in rollovers. Hand-in-hand with the seat belt rule, this final rule enhances the safety of these belted passengers by providing a “survival space” in a rollover, a space where the belted occupants are protected from intruding structures such as a collapsing roof or a detached luggage rack. The new standard's improvements to the roof and sidewall strength of the buses will also protect unbelted occupants against structural failure of the bus compartment. This final rule improves transportation safety for the most vulnerable in our society since more than half of motorcoach trips are made by children and senior citizens.

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It furthers transportation equity by providing the same occupant crash protection to these passengers as the protection provided to occupants of other passenger motor vehicles,

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by reducing deaths and injuries due to the crushing of the roof into the occupant compartment in rollover crashes.

5

“Motorcoach Census 2013, A Study of the Size and Activity of the Motorcoach Industry in the United States and Canada in 2012,” American Bus Association Foundation, February 27, 2014.

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Passenger vehicles under 4,536 kg (10,000 lb) GVWR are subject to the requirements of FMVSS No. 216, “Roof crush resistance; Applicable unless a vehicle is certified to § 216a,” or to FMVSS No. 216a, “Roof crush resistance, Upgraded standard.”

This final rule applies to all new large buses, with limited exceptions. The standard does not apply to school buses, prison buses, buses with perimeter seating, or to transit buses that are not OTRBs. School buses already meet an FMVSS for roof strength, which is FMVSS No. 220, “School bus rollover protection” (49 CFR 571.220). In response to comments, NHTSA has also decided not to apply the standard to “school bus derivative buses,” which this final rule defines as buses built on a school bus platform. These vehicles may not have school bus lights and stop arms meeting FMVSS No. 108 and No. 131, respectively, or seating systems meeting FMVSS No. 222, “School bus seating and passenger protection,” but the buses have safety systems that are otherwise identical to school buses regarding their emergency exits, rollover protection (FMVSS No. 220), bus body joint strength, and fuel system integrity. The vehicles could be certified as meeting the FMVSSs for “school buses” if they had school bus lights meeting FMVSS No. 108, stop arms meeting FMVSS No. 131, and seating systems meeting FMVSS No. 222. Because school bus derivative buses already meet the roof crush resistance requirements in FMVSS No. 220, it would be redundant to require the buses to meet Standard No. 227 established by this final rule.

The test for the large buses adopted by this final rule is the complete vehicle rollover test of United Nations Economic Commission for Europe (ECE) Regulation 66, “Uniform Technical Prescriptions Concerning the Approval for Large Passenger Vehicles with Regard to the Strength of their Superstructure,” (ECE R.66).

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The test simulates a real-world rollover crash of a large bus. The test bus is placed on a tilting platform that is 800 mm (24 inches) above a smooth and level concrete surface. One side of the tilting platform along the length of the bus is raised at a steady rate of not more than 5 degrees/second until the vehicle becomes unstable, rolls off the platform, and impacts the concrete surface below. Some commenters to the August 6, 2014 notice of proposed rulemaking (NPRM) (79 FR 46090) thought that the test was too lenient, but NHTSA believes that those views are mistaken. As explained in this preamble, this test imparts severe crash forces that the buses must resist. FMVSS No. 227 prohibits any intrusion into the “survival space” by any part of the vehicle outside the survival space, except for minute objects weighing less than 15.0 grams, such as pebbles of glazing, or bolts and screws, which do not pose an unreasonable risk to safety for occupants.

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Dated February 2006,

https://live.unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/r066r1e.pdf

. ECE R.66 defines “superstructure” as “the load-bearing components of the bodywork as defined by the manufacturer, containing those coherent parts and elements which contribute to the strength and energy absorbing capability of the bodywork, and preserve the residual space in the rollover test.” “Bodywork” means “the complete structure of the vehicle in running order, including all the structural elements which form the passenger compartment, driver's compartment, baggage compartment and spaces for the mechanical units and components.”

The “survival space” requirement ensures at least a minimum level of structural integrity for the buses by prohibiting intrusions into the occupant space that can cause harm. It establishes “improved roof and roof support standards” that substantially improve the resistance of the roof to deformation and intrusion, in accordance with MAP-21. It ensures that buses are constructed so that structures outside of the survival space, such as luggage racks and large pieces of glazing, do not enter the survival space in the rollover.

The requirement that emergency exits remain shut during and after the rollover test reduces the likelihood of emergency exits becoming ejection portals during rollovers, which is a goal consistent with MAP-21. Section 32703(b)(2) of MAP-21 requires NHTSA to consider requiring advanced glazing

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standards for each motorcoach portal and “other portal improvements to prevent partial and complete ejection of motorcoach passengers, including children.” In NHTSA's motorcoach tests conducted during development of this rulemaking, roof and side emergency exits opened during the rollover event and the panes of advanced glazing popped out of their mounting. The requirement that emergency exits remain closed is a “portal improvement” established pursuant to section 32703(b)(2). Additionally, the requirement that the glazing panels not intrude into the survival space by detaching from the non-struck side of the bus will ensure the glazing panels remain intact in their mounting during bus rollover crashes and not form ejection portals.

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MAP-21 (section 32702(1)) defines “advanced glazing” as “glazing installed in a portal on the side or the roof of a motorcoach that is designed to be highly resistant to partial or complete occupant ejection in all types of motor vehicle crashes.”)

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On May 6, 2016 (81 FR 27904), NHTSA issued an NPRM proposing to establish FMVSS No. 217a to improve glazing materials used in motorcoaches and other large buses. The NPRM proposed an impactor test of glazing material to simulate the loading from an average size adult male impacting a window on the opposite side of a large bus in a rollover. Countermeasures used to meet the test would likely involve the use of advanced glazing. This final rule adopting FMVSS No. 227 would complement FMVSS No. 217a by improving the securement of the advanced glazing in the buses.

b. How This Final Rule Differs From the Notice of Proposed Rulemaking (NPRM)

The most noteworthy differences between this final rule and the NPRM

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are highlighted below.

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NPRM, August 6, 2014 (79 FR 46090).

1. This final rule adopts the NPRM's proposed ECE R.66 full vehicle test to improve the roof and structural integrity of OTRBs (except for a few buses with unique configurations), and non-OTRBs with a GVWR greater than 11,793 kg (26,000 lb)). The agency proposed to exclude non-OTRBs with perimeter seating from the standard. After evaluation of the comments received, this final rule excludes all perimeter seating buses, as there is not a sufficient reason to distinguish between buses just based on the location of a luggage compartment. Further, all prison buses are excluded due to the unique interior configuration of the buses, as are school bus derived buses, as the latter vehicles already meet NHTSA's school bus roof crush resistance standard.

2. This final rule adopts the NPRM's proposed prohibition that no part of the bus that is outside the survival space shall intrude into the survival space, both during movement of the tilting platform or resulting from impact of the bus on the impact surface. However, given the high force applications imparted to the bus structure in the rollover test, this final rule permits debris caused by the impact to fall into the survival space, such as small glazing pebbles or bolts and screws. The objects must not weigh more than 15.0 grams.

3. This final rule does not adopt the NPRM's proposal that each anchorage of an interior overhead luggage rack or other compartment must not completely separate from its mounting structure during movement of the tilting platform or resulting from impact of the bus on the impact surface. This final rule also does not adopt the NPRM's proposal that seat anchorages must not become dislodged during the test. Under the NPRM, those proposed prohibitions would have applied even if the luggage rack does not enter the survival space, or the seat anchorages dislodged within the survival space. NHTSA has decided that the primary purpose of this rulemaking is to establish a roof strength and crush resistance standard that improves the resistance of roofs to deformation and intrusion,

i.e.,

by providing a survival space to occupants in rollovers. The purpose is achieved by prohibiting

any

structure, such as overhead luggage racks, from intruding into the survival space. By prohibiting overhead luggage racks from impeding into the survival space in the rollover, overhead luggage racks will have to be better anchored to the bus wall than they had in the past so that they do not detach and intrude into the survival space in the test. Thus, the proposed luggage rack provision is not needed to ensure that a survival space is provided since luggage racks are prohibited from intruding on the survival space. Similarly, the proposed seat anchorage provision is not necessary to achieve a survival space for occupants.

4. This final rule does not adopt the proposed provision that each side window glazing opposite the impacted side of the vehicle must remain attached to its mounting structure so as not to allow the passage of a 102 mm (5-inch) diameter sphere. The sphere test was proposed to ensure that, after the rollover test, the glazing remain firmly attached to its mounting. Because the primary purpose of this rulemaking is to provide a necessary survival space to occupants in rollovers, the purpose is achieved by prohibiting panes of glazing from falling into the survival space. The proposed requirement that the glazing not form openings is not germane to the survival space specification and unnecessarily complicates this rulemaking.

These changes and others are discussed in this preamble.

c. NTSB Recommendations

This final rule accords with the following National Transportation Safety Board (NTSB) recommendations that NTSB issued to NHTSA to improve motorcoach safety.

In an NTSB Highway Special Investigation Report (1999), Bus Crashworthiness Issues,

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NTSB cited an October 1971 rollover of a 1970 Motor Coach Industries (MCI) bus as justification for the following recommendations:

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National Transportation Safety Board. 1999,

Bus Crashworthiness Issues

. Highway Special Investigation Report NTSB/SIR-99/04. Washington, DC.

“H-99-50 (MW): In 2 years, issue performance standards for motorcoach roof strength that provide maximum survival space for all seating positions and that take into account current typical motorcoach window dimensions.”

“H-99-51: Once performance standards have been developed for motorcoach roof strength, require newly manufactured motorcoaches to meet those standards.”

In November 2009, after investigating an August 2008 Sherman, Texas bus crash,

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the NTSB issued two safety recommendations. In this rollover crash, the failure of the overhead luggage rack on the vehicle impeded passenger egress and rescue efforts. Thus, NTSB stated that the Sherman accident and NHTSA's motorcoach testing indicate that the lack of standards for overhead luggage racks on motorcoaches leaves passengers at risk of serious injury from interaction with overhead luggage racks in a crash and made the following recommendations:

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NTSB/HAR-09/02 PB2009-916202; Motorcoach Run-Off-the-Bridge and Rollover Sherman, Texas August 8, 2008; October 2009;

https://www.ntsb.gov/investigations/AccidentReports/Reports/HAR0902.pdf

, last accessed 09/08/2021.

“H-09-23: Develop performance standards for newly manufactured motorcoaches to require that overhead luggage racks remain anchored during an accident sequence.”

“H-09-24: Develop performance standards for newly manufactured motorcoaches that prevent head and neck injuries from overhead luggage racks.”

This final rule is consistent with the above NTSB recommendations. NHTSA is issuing performance standards for motorcoach roof strength that provide a survival space for all seating positions and is requiring new motorcoaches to meet those requirements. The standard established by this final rule requires that overhead luggage racks remain anchored during a rollover such that they do not enter the requisite survival space and injure passengers in the survival space.

d. Costs and Benefits

NHTSA has examined the benefits and costs of this final rule to ensure that the agency adopts only those amendments that contribute to improved safety and that are consistent with the directives of MAP-21 and the principles for regulatory decision-making set forth in Executive Order 12866,

Regulatory Planning and Review

. Over the 15-year period between 2004 and 2018, on average 22 fatalities occurred annually to occupants of these buses. Though a relatively small percentage of overall traffic fatalities, data show that rollover crashes are particularly deadly for large buses. Among the 122 fatal crashes, 56 were rollover crashes resulting in 189 fatalities. This final rule enhances passenger protection in rollover crashes in a reasonable and achievable way. As discussed in the next section, NHTSA adopts this final rule because a rollover structural integrity standard meets the requirements and considerations in

subsections (a) and (b) of section 30111 of the Safety Act. This rule provides safety to passengers in a reasonable, objective, and cost-effective manner while harmonizing the standard internationally.

NHTSA has determined this rulemaking to be cost beneficial.

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NHTSA has developed a Final Regulatory Evaluation (FRE) that discusses issues relating to the potential costs, benefits and other impacts of this regulatory action. The FRE is available in the docket for this final rule and may be obtained by downloading it or by contacting Docket Management at the address or telephone number provided at the beginning of this document.

The agency estimates the annual cost of this final rule to be between $4.81 million and $11.84 million (see Table 1 below). The countermeasures may include stronger roof structure, support pillars, side walls, shock resistant latches for emergency exits, and improved window mounting, resulting in material costs for each bus covered under this final rule ranging from $325 to $591. We estimate the total weight increase will range from 181 to 356 kilograms (kg) (399 to 784 pounds (lb)) for each of these buses and cost an additional $1,862 to $4,790 in fuel per vehicle over the lifetime of the vehicle.

We estimated the benefits of this rule taking into account the benefits attributable to the agency's final rules on seat belts and electronic stability control (ESC), as those rules also applied to this universe of vehicles. We estimate that requiring the subject buses to meet the rollover structural integrity performance criteria will save approximately 2-3 lives annually. In addition, we expect that the rule will reduce the number of seriously injured occupants by 4 annually. Thus, we estimate that approximately 3.12 equivalent lives are saved annually if 15 percent of occupants use seat belts, and approximately 2.45 equivalent lives are saved annually (undiscounted) if 90 percent of occupants use seat belts (see Table 2 below).

The cost per equivalent life saved is estimated to be $2.48 million to $4.99 million when belt use is estimated to be 15 percent, and $3.17 million to $6.38 million when belt use is estimated to be 90 percent (see Table 3 below). The net cost/benefit impact ranges from a net benefit of $13.09 million to $23.31 million if seat belt usage is 15 percent. If the seat belt usage rate is 90 percent, the estimated net cost/benefit impact ranges from a net benefit of $8.25 million to a net benefit of $16.97 million (see Table 4 below). While the cost and benefits of this rule will vary depending on the material/fuel costs per vehicle and on the belt use rate, per all available information this final rule will be cost beneficial.

Table 1—Estimated Annual Costs

[2020 Dollars]

Potential Costs:

Material Costs per Vehicle

$325 to $591.

Material Costs, Total New Fleet

$0.71 million to $1.30 million.

Fuel Costs per Vehicle @ 3%

$2,441 to $4,790.

Fuel Costs per Vehicle @ 7%

$1,862 to $3,654.

Fuel Costs, Total New Fleet

$4.10 million to $10.54 million.

Total Annual Cost

$4.81 million to $11.84 million.

Table 2—Estimated Annual Benefits

[Undiscounted equivalent lives saved]

15 percent belt usage

3.12

90 percent belt usage

2.45

Table 3—Cost per Equivalent Life Saved

[Across 3% and 7% discount, in millions of 2020 dollars]

15 percent belt usage

2.48-4.99

90 percent belt usage

3.17-6.38

Table 4—Annualized Costs and Benefits

[In millions of 2020 dollars]

Annual costs

Annual benefits

Net Benefits

15% belt usage:

3% Discount Rate

6.08-11.84

29.40

17.56-23.31

7% Discount Rate

4.81-9.34

22.43

13.09-17.61

90% belt usage:

3% Discount Rate

6.08-11.84

23.05

11.21-16.97

7% Discount Rate

4.81-9.34

17.59

8.25-12.78

e. NHTSA's Determination of MAP-21 Requirements and Considerations

Section 32703(b) and (b)(1) of MAP-21 direct NHTSA: (a) To establish improved roof and roof support standards for motorcoaches that substantially improve the resistance of motorcoach roofs to deformation and intrusion to prevent serious occupant injury in rollover crashes involving motorcoaches; if (b) NHTSA determines that such standards meet the requirements and considerations set forth in subsections (a) and (b) of section 30111 of the Safety Act. In addition, section 32703(b)(2) directs NHTSA to consider portal improvements to prevent partial and

complete ejection of motorcoach passengers, including children, if such standards meet the requirements and considerations set forth in subsections (a) and (b) of section 30111 of the Safety Act.

NHTSA has determined that the standard issued by this final rule meets the requirements and considerations of section 30111(a) and (b) of the Safety Act.

Section 30111(a)

The provision at 49 U.S.C. 30111(a) of the Safety Act authorizes the Secretary (NHTSA, by delegation) to prescribe Federal motor vehicle safety standards that are practicable, meet the need for motor vehicle safety, and are stated in objective terms. “Motor vehicle safety” is defined in the Safety Act as “the performance of a motor vehicle or motor vehicle equipment in a way that protects the public against unreasonable risk of accidents occurring because of the design, construction, or performance of a motor vehicle, and against unreasonable risk of death or injury in an accident, and includes nonoperational safety of a motor vehicle.”

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49 U.S.C. 30102(a)(8).

NHTSA has determined that the standard issued by this final rule meets the requirements and considerations of section 30111(a) of the Safety Act. The standard is practicable, since it is based on the 2006 ECE R. 66 complete vehicle rollover test. New buses sold in Europe and other countries have been designed to meet the ECE R.66 rollover test requirements for over a decade. Further, NHTSA has conducted the vehicle rollover test of ECE R.66 in developing the NPRM. The three bus rollover tests the agency conducted using the ECE R.66 complete vehicle rollover test procedure showed that the test is feasible and practical for evaluating how well a bus structure maintains occupant survival space in a rollover. The standard is also cost beneficial, and thus is economically practicable.

Standard No. 227 meets the need for safety. Two of the real-world rollover crashes examined for this rule involved buses that had complete roof separation during the rollovers.

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Almost all the passengers in those two crashes were ejected due to the loss of the bus roofs. This standard will increase the likelihood that bus structures maintain their roof structure and provide a residual survival space for the vehicle occupants. Studies of bus structures before and after implementation of ECE R.66 have concluded those requirements are effective in protecting bus occupants in rollover crashes.

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A bus design in use prior to ECE R.66 experienced complete structural collapse of the roof in a rollover crash with one and a half full 360 degree rolls down a 6-meter embankment. That bus model redesigned to meet ECE R.66 requirements was able to maintain adequate survival space in a rollover crash with two and a quarter full 360 degree rolls down a 9-10 meter embankment.

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15

These rollover crashes occurred in Turrell, Arkansas in 2004 and Mexican Hat, Utah in 2008.

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Matolcsy, M. (2007), “The Severity of Bus Rollover Accidents,” Enhanced Safety of Vehicles (ESV) Paper 07-152, 20th ESV Conference, Lyon, France.

Available at: https://www-esv.nhtsa.dot.gov/Proceedings/20/07-0152-O.pdf

, last accessed April 26, 2021.

17

Matolcsy, M. (2006), “Rollover accident with ejection of occupants.” Informal working document of GRSG, No. GRSG-91-7. GRSG, 91st session, Geneva, October 2006.

This final rule meets the need for safety on many fronts. NHTSA's Motorcoach Safety Action Plan targeted safety improvements for buses to reduce the incidence of fatalities and serious injuries caused by bus rollover accidents. The seat belt requirements in FMVSS No. 208

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for large buses provided a means for belted bus occupants to remain within the survival space in a crash. Buses designed to FMVSS No. 227 will provide a survival space for bus occupants. Anti-ejection requirements adopted for bus window portals

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will reduce the incidence of partial ejection of belted occupants as well as reduce the occurrence of partial or full ejection of unbelted occupants. Further, NHTSA has proposed to establish an FMVSS to require advanced glazing that is highly resistant to occupant ejection for each motorcoach portal, pursuant to section 32703(b)(2) of MAP-21.

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This final rule adopting FMVSS No. 227 would complement FMVSS No. 217a by improving the securement of the advanced glazing in the buses.

18

78 FR 70416, November 25, 2013.

19

81 FR 27904, May 6, 2016.

20

May 6, 2016 (81 FR 27904), supra.

The available information shows this final rule is cost beneficial. NHTSA estimates that requiring the subject buses to meet the performance criteria in this final rule will save approximately 2-3 lives and prevent 4 serious injuries annually. NHTSA estimates the net benefits range from $8.3 million to $23.3 million.

Standard No. 227 is stated in objective terms. The residual survival space is well defined, based upon a specified boundary at each transverse cross-section of the vehicle, with the cross-sections bounded by specified forwardmost and rearmost vehicle landmarks. Potential intrusion into the residual survival space may be objectively measured using standard test measurement methodologies-such as templates representing the outline of the residual survival space and high-speed video. The FMVSS No. 227 test procedure matches the full vehicle test procedure of ECE R.66. Studies have shown the ECE R.66 full vehicle rollover test to be a relatively severe loading condition replicating real-world bus rollover crashes.

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21

Matolcsy, M. (2007), “The Severity of Bus Rollover Accidents,” Enhanced Safety of Vehicles (ESV) Paper 07-152, 20th ESV Conference, Lyon, France.

Available at: https://www-esv.nhtsa.dot.gov/Proceedings/20/07-0152-O.pdf

, last accessed April, 26 2021.

Section 30111(b)

The provision at 49 U.S.C. 30111(b) specifies that, when prescribing such standards, the Secretary must consider all relevant, available motor vehicle safety information, consult with the states as appropriate, consider whether a standard is reasonable, practicable, and appropriate for the types of motor vehicles or motor vehicle equipment for which it is prescribed, and consider the extent to which the standard will carry out the statutory purpose of section 30101 of the Act. Section 30101 states that the purpose of the statute is to reduce traffic accidents and deaths and injuries resulting from traffic accidents, and that it is therefore necessary to prescribe FMVSS, and to carry out needed safety research and development.

NHTSA has issued this final rule in accordance with section 30111(b). As discussed throughout this document, the agency concludes, after comprehensive reviews of relevant available safety information that includes over 15 years of crash data and development of a NHTSA plan for motorcoach safety,

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that adopting FMVSS No. 227 meets the requirements and considerations of the Safety Act. NHTSA has provided the public with opportunities to review and provide input on the agency's safety plan and comment on adoption of this structural integrity final rule when it was in proposed form. This final rule accords with National Transportation Safety Board Recommendations H-99-50, H-99-51, H-09-23, and H-09-24, and NHTSA expects wide public support overall for this final rule. NHTSA has determined that FMVSS No. 227 is reasonable and appropriate for the

vehicles to which the standard applies for improving bus occupant protection in rollover crashes and that establishing FMVSS No. 227 meets the purpose and policy of the Safety Act.

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NHTSA's Approach to Motorcoach Safety (2007), (Docket No. NHTSA-2007-28793-001), supra.

f. Retrofitting

NHTSA has decided not to require existing large buses to meet the requirements adopted today for new buses. None of the commenters supported a retrofitting requirement. Based on its tests of older buses, the agency believes that many existing buses may need major structural changes to the vehicle's sidewall and roof structure to meet the requirements adopted in this document. Such structural changes are likely to be cost-prohibitive, making retrofitting impracticable.

II. Introduction

Over the 15-year period between 2004 and 2018, data from NHTSA's Fatality Analysis Reporting System (FARS) indicate there were 122 fatal crashes involving large buses. These crashes resulted in 326 occupant fatalities (274 passenger and 52 driver fatalities). During this period, on average 22 fatalities occurred annually to occupants of these buses.

Data indicate that rollover crashes are a particular safety problem for these buses. Among the 122 fatal crashes, 56 were rollover crashes resulting in 189 fatalities. While fatal rollover crashes constitute about 43 percent of all fatal crashes involving these bus types, they represent about 58 percent of all the occupant fatalities. Further, 56 percent of the rollover crash fatalities were attributable to occupant ejections (106 ejection fatalities out of the total of 189 fatalities in bus rollover crashes).

Congress was especially concerned about motorcoach rollover crashes in passing provisions of MAP-21 relevant to this final rule. MAP-21 requires DOT to “establish improved roof and roof support standards for motorcoaches that substantially improve the resistance of motorcoach roofs to deformation and intrusion to prevent serious occupant injury in rollover crashes involving motorcoaches” if such standards meet the requirements and considerations set forth in subsections (a) and (b) of section 30111 of title 49, United States Code.

23

Under MAP-21, “motorcoach” means an OTRB, but does not include a bus used in public transportation provided by, or on behalf of, a public transportation agency, or a school bus. MAP-21

24

also directs DOT to consider “portal improvements to prevent partial and complete ejection of motorcoach passengers, including children.”

23

MAP-21, section 32703(b)-(b)(1).

24

Id.,

section 32703(b)(2).

In accordance with MAP-21 and the Safety Act, we have issued this rollover-specific rule to apply to buses associated with an unreasonable risk of fatal rollover involvement. Thus, this final rule applies to OTRBs, and to all non-OTRBs with a GVWR greater than 11,793 kg (26,000 lb) (large buses), with some exceptions. The final rule excludes school buses, prison buses, non-OTRB transit buses, and buses with perimeter seating.

25

We have applied this rule to meet the requirements and considerations of MAP-21 and the Safety Act.

25

Under the standard, a bus with perimeter seating is a bus with 7 or fewer designated seating positions rearward of the driver's seating position that are forward-facing or can convert to forward-facing without the use of tools.

NHTSA is enhancing the safety of large buses in rollovers both by providing a survival space in the occupant compartment, and by reducing the likelihood of emergency exits opening during bus rollovers and becoming ejection portals. NHTSA achieved an important first step enhancing the safety of the buses in rollovers by the November 25, 2013 final rule that requires lap/shoulder belts for all passengers in large capacity buses.

26

This final rule builds on the rollover protection provided by seat belts by ensuring the buses provide a protective survival space for belted and unbelted retained occupants in rollovers. The 2013 seat belt rule significantly increased the ability of occupants of large buses to be retained in the bus structure in rollover crashes. This final rule provides the retained occupants a survival space in the bus structure, and strengthens the bus structure and emergency exit portals to protect unbelted occupants as well.

26

NHTSA estimates that seat belts are 77 percent effective in preventing fatalities in rollover crashes.

III. NHTSA's Statutory Authority

NHTSA is issuing this final rule pursuant to and in accordance with its authority under the National Traffic and Motor Vehicle Safety Act and the relevant provisions of MAP-21.

a. National Traffic and Motor Vehicle Safety Act (Safety Act)

Under 49 United States Code (U.S.C.) Chapter 301, Motor Vehicle Safety (49 U.S.C. 30101

et seq.

), the Secretary of Transportation is responsible for prescribing motor vehicle safety standards that are practicable, meet the need for motor vehicle safety, and are stated in objective terms (section 30111(a)). “Motor vehicle safety” is defined in the Safety Act (section 30102(a)(8)) as “the performance of a motor vehicle or motor vehicle equipment in a way that protects the public against unreasonable risk of accidents occurring because of the design, construction, or performance of a motor vehicle, and against unreasonable risk of death or injury in an accident, and includes nonoperational safety of a motor vehicle.” “Motor vehicle safety standard” means a minimum standard for motor vehicle or motor vehicle equipment performance (section 30102(a)(9)). When prescribing such standards, the Secretary must consider all relevant available motor vehicle safety information (section 30111(b)(1)). The Secretary must also consider whether a proposed standard is reasonable, practicable, and appropriate for the particular type of motor vehicle or motor vehicle equipment for which it is prescribed (section 30111(b)(3)) and the extent to which the standard will further the statutory purpose of reducing traffic accidents and associated deaths and injuries (section 30111(b)(4)). The responsibility for promulgation of FMVSSs is delegated to NHTSA (49 CFR 1.95).

b. MAP-21 (Incorporating the Motorcoach Enhanced Safety Act of 2012)

NHTSA is issuing this final rule in accordance with MAP-21, which incorporates the “Motorcoach Enhanced Safety Act of 2012” into Subtitle G.

27

Section 32703(b) of MAP-21 requires the Secretary (NHTSA by delegation) to prescribe regulations that would address certain aspects of motorcoach crash performance within two years if the agency determines that the standards would meet the requirements and considerations of section 30111(a) and (b) of the National Traffic and Motor Vehicle Safety Act.

28

27

Moving Ahead for Progress in the 21st Century Act, Public Law 112-141 (Jul. 6, 2012).

28

Id.

at section 32703(b).

There are two subsections of section 32703(b) that are particularly relevant to this final rule. Subsection (b)(1) specifies that the Secretary is to establish improved roof and roof support standards that “substantially improve the resistance of motorcoach roofs to deformation and intrusion to prevent serious occupant injury in rollover crashes involving motorcoaches.” Subsection (b)(2) directs the Secretary to “consider advanced glazing standards for each motorcoach portal and [to] consider other portal

improvements to prevent partial and complete ejection of motorcoach passengers, including children.”

29

29

While this final rule is mainly aimed at addressing the rollover structural integrity of specific large bus types, the reduced deformation of the bus structure would ensure that any advanced glazing installed on portals would be retained on their mounting and reduce the risk of occupant ejection in rollover crashes. Further, the requirement that emergency exits should not open during the rollover test would also ensure that the exits do not become ejection portals. Thus, both subsection (b)(1) and subsection (b)(2) are relevant to this rule.

MAP-21 contains other provisions pertaining to this rulemaking. Section 32702 states that “motorcoach” has the meaning given to the term “over-the-road bus” in section 3038(a)(3) of the Transportation Equity Act for the 21st Century (TEA-21).

30

Section 3038(a)(3) of TEA-21 (see 49 U.S.C. 5310 note) defines “over-the-road bus” as “a bus characterized by an elevated passenger deck located over a baggage compartment.” However, section 32702 of MAP-21 excludes transit buses and school buses from the “motorcoach” definition.

31

30

Moving Ahead for Progress in the 21st Century Act, Public Law 112-141, section 32702(6).

31

Id.

at section 32702(6)(A)-(B).

MAP-21 further directs the Secretary to apply any regulation prescribed in accordance with section 32703(b) to all motorcoaches manufactured more than 3 years after the date on which the regulation is published.

32

In addition, the Secretary may assess the feasibility, benefits, and costs of applying any requirement established under section 32703(b)(2) to “motorcoaches manufactured before the date on which the requirement applies to new motorcoaches” (retrofit).

33

Finally, MAP-21 also authorizes the Secretary to combine the required rulemaking actions as the Secretary deems appropriate.

34

32

Id.

at section 32703(e)(1).

33

Id.

at section 32703(e)(2). “Retrofit Assessment for Existing Motorcoaches.”

34

Id.

at section 32706.

IV. Safety Need (FARS 2004-2018 Data Analysis)

This rulemaking is conducted pursuant to the requirements of the Safety Act and MAP-21. It investigates whether there are unreasonable safety risks associated with rollover crashes in OTRB transportation, and if there are such risks, whether those safety risks can be reasonably reduced by having at least minimum levels of performance specified for rollover structural integrity and portal improvements.

This rulemaking improves occupant safety in large bus rollover crashes. While developing the November 25, 2013 seat belt final rule, NHTSA found that most fatalities in OTRB crashes are attributable to rollovers. Because more than half of the rollover fatalities are attributable to ejections, NHTSA issued a seat belt requirement to mitigate those ejections.

Enhancing the structural integrity of the interior of these buses works together with the seat belt rule. More occupants will be able to be retained in the bus compartment because of the belts, so it makes sense to require a survival space that protects these restrained occupants in a rollover. Moreover, regardless of whether occupants are belted, data

35

show that the risk of serious injuries and fatalities can be reduced by improving the vehicle structure to protect occupants against collapsing roofs and bus components falling or intruding into the survival space. Additionally, emergency exits should remain closed in a crash, as an open exit forms a portal through which occupants could be completely or partially ejected. This final rule adopts requirements to meet these objectives.

36

35

Maétolcsy, M (2012), “Passenger's Ejection in Bus Rollover Accident,” FISITA 2012 World Automotive Congress, paper F2012 F02-005. Available at

https://unece.org/DAM/trans/doc/2012/wp29grsg/GRSG-103-02e.pdf

. Last accessed May 03, 2021.

36

This final rule does not address the issue of glazing breaking in a rollover crash that would result in openings through which occupants could be completely or partially ejected even if emergency exits remain closed. This matter is addressed in the 2016 NPRM for advanced glazing (81 FR 27904),

supra

.

Updated Data Analysis (FARS Data 2004-2018)

After the August 6, 2014 NPRM, NHTSA re-analyzed FARS data files for the years 2004 to 2018 to assess the impacts of this rulemaking.

37

The bus body types coded in FARS are “school bus,” “transit bus,” “cross country/intercity bus” to represent OTRBs (motorcoaches), “other bus” to represent other types of buses, and “unknown bus” to represent buses that could not be categorized into the other four bus body type categories. Since 2011, a new bus body type, “van-based buses” was included. We also examined the FARS body type “Large Van” for van-based bus crashes for the years 2004-2018 where the vehicle was used to transport people. The buses can also be categorized by their GVWR: GVWR less than or equal to 10,000 lb, GVWR greater than 10,000 lb and less than or equal to 26,000 lb, and GVWR greater than 26,000 lb. The manner in which a bus was used is coded in FARS as “school bus,” “intercity bus,” “transit/city bus,” “shuttle bus,” and “modified for personal/private use.”

37

Later in this preamble we discuss our analysis of updated data regarding buses with a GVWR of 10,000-26,000 lb.

To assess the benefits and costs of this rule, the agency selected buses of body type “over-the-road bus (OTRB)” regardless of GVWR

38

and “other bus,” “unknown bus” and “van-based bus” body types with a GVWR greater than 26,000 lb, regardless of the manner in which they were used.

39

NHTSA also included fatal crashes of large vans with a GVWR greater than 26,000 lb used for transporting people (used as intercity bus, charter/tour bus, commuter bus, and shuttle bus) and found none for the 15-year period from 2004 to 2018.

38

All OTRBs (cross country/intercity buses) are covered under MAP-21.

39

Crashes and fatalities of unknown GVWR buses were proportionally distributed amongst the known values.

For the 15-year period from 2004 to 2018, there were a total of 326 bus occupant fatalities in the bus types covered by of FMVSS No. 227 (see Table 5). Among these fatalities, 230 were occupants of OTRBs with a GVWR greater than 26,000 lb, 15 were occupants of OTRBs with GVWR <26,000 lb, and 81 were occupants in buses coded as “other bus,” “unknown bus,” and “van-based bus” with a GVWR greater than 26,000 lb. In this 15-year period, fatalities among occupants of OTRBs account for 75 percent of the 326 fatalities.

Table 5—Bus Crash Occupant Fatalities in the Bus Types Covered by FMVSS No. 227

[FARS data 2004-2018]

Year

OTRB

GVWR

<26,000 lb

OTRB

GVWR

>26,000 lb

Other bus GVWR

>26,000 lb

Unknown bus GVWR

>26,000 lb

Van-based GVWR

>26,000 lb

Total

2004

0

23

4

0

27

2005

0

10

3

4

17

2006

0

8

2

3

13

2007

1

18

8

0

27

2008

0

38

2

0

40

2009

0

9

1

0

10

2010

0

11

1

0

12

2011

0

30

0

0

30

2012

2

12

1

0

1

16

2013

9

8

3

1

0

21

2014

1

18

5

1

0

25

2015

0

12

3

6

0

21

2016

1

8

26

0

0

35

2017

1

5

1

0

0

7

2018

0

13

5

0

0

18

Total

15

230

65

15

1

326

The bus occupant fatalities were further classified by the type of crash (rollover, front, side, rear). FARS also coded fatal bus events “other” that could not be classified into one of the four crash types. The bus occupant fatalities in these “other” bus crash types were further analyzed and found to result from occupants jumping or falling off the bus, bus fire, explosion inside the bus, heavy object falling on an occupant, and fatal injuries to an occupant that are not crash related. Because these fatalities were not crash related, we did not include them in the count of bus crash fatalities.

In the 15-year period from 2004 to 2018, there were 122 fatal bus crashes of bus types covered by FMVSS No. 227, among which 71 involved OTRBs with a GVWR greater than 26,000 lb (Table 6). Among the 122 crashes, 56 were rollover events, 59 were frontal crashes, 7 were side crashes, and 0 were rear crashes.

Table 6—Fatal Crashes of Bus Types Covered by FMVSS No. 227

[FARS 2004-2018]

Bus body type and GVWR

Rollover

Frontal

Side

Rear

Total

OTRB (GVWR ≤26,000 lb)

7

2

0

0

9

OTRB (GVWR >26,000 lb)

35

33

3

0

71

Other (GVWR >26,000 lb)

11

18

3

0

32

Unknown (GVWR >26,000 lb)

3

5

1

0

9

Van-based (GVWR >26,000 lb)

0

1

0

0

1

Total

56

59

7

0

122

The 122 fatal bus crashes (involving bus types covered under FMVSS No. 227) resulted in 326 bus occupant fatalities (52 drivers and 274 passengers), as shown in Table 7. Among these fatalities, 189 persons (11 drivers, 178 passengers) died in 56 rollover crashes. In contrast, 116 persons (40 drivers, 76 passengers) died in 59 frontal crashes. Bus rollover crashes accounted for 58 percent of the total bus occupant fatalities and 65 percent of the passenger fatalities.

These data show the devastating nature of bus rollover events, where a significant number of fatal or serious injuries can occur in a single bus rollover event. Among the 189 fatalities in bus rollover events, 149 fatalities (79 percent) were in OTRBs with a GVWR greater than 26,000 lb.

Table 7—Bus Occupant Fatalities in Crashes of Bus Types Covered by FMVSS No. 227 by Bus Body Type, GVWR, Crash Type, and Occupant Type

[FARS data 2004-2018]

Bus body type and GVWR

Rollover

Driv

Pass

Front

Driv

Pass

Side

Driv

Pass

Rear

Driv

Pass

All types

Driv

Pass

Total Driv ± Pass

OTRB (GVWR ≤26,000 lb)

2

11

1

1

0

0

0

0

3

12

15

OTRB (GVWR >26,000 lb)

7

142

25

46

1

9

0

0

33

197

230

Other (GVWR >26,000 lb)

1

23

12

23

0

6

0

0

13

52

65

Unknown (GVWR >26,000 lb)

1

2

2

5

0

5

0

0

3

12

15

Van-based (GVWR >26,000 lb)

0

0

0

1

0

0

0

0

0

1

1

Total

11

178

40

76

1

20

0

0

52

274

326

NHTSA also examined bus rollover events by the ejection status of occupants, among bus types covered by FMVSS No. 227 (see Table 8). Among the 178 passenger fatalities in bus rollover events, 98 were to occupants ejected or partially ejected from the bus.

Table 8—Bus Occupant Fatalities in Rollovers in Bus Types Covered by FMVSS No. 227 by Bus Body Type, GVWR, Occupant Type, and Ejection Status

[FARS 2004-2013]

Bus body type and GVWR

Driver

Not ejected

Ejected

Passenger

Not ejected

Ejected

OTRB (GVWR ≤26,000 lb)

0

2

4

7

OTRB (GVWR >26,000 lb)

3

4

60

82

Other bus (GVWR >26,000 lb)

0

1

16

7

Unknown bus (GVWR >26,000 lb)

0

1

0

2

Van-based bus (GVWR >26,000 lb)

0

0

0

0

Total

3

8

80

98

These data show that while transportation by OTRBs (and other similar large buses) is an overall safe form of transportation, given the high occupancy of these vehicles, a significant number of fatal or serious injuries can occur in a single crash. This is especially true in bus rollover crashes that result in occupant ejections.

V. Summary of the NPRM

The NPRM underlying this final rule published August 6, 2014 (79 FR 46090). The agency proposed adoption of a new FMVSS No. 227 to set performance requirements that large buses must meet when tested using the full vehicle ECE R.66 test.

In support of the NPRM, the agency researched two existing roof crush/rollover standards: FMVSS No. 220, “School bus rollover protection,” and ECE R.66, “Uniform Technical Prescriptions Concerning the Approval of Large Passenger Vehicles with Regard to the Strength of their Superstructure.”

40

The agency purchased three different bus models for this test program. Two older models were selected because they were representative of the range of roof characteristics (such as design, material, pillars, shape, etc.) of large bus roofs in the U.S. fleet. The vehicles selected were two 12.2 meters (m) (40 feet) long model year (MY) 1992 MCI model MC-12, and two 12.2 m (40 feet) long MY 1991 Prevost model (Prevost) LeMirage buses. The agency also procured a MY 2000 MCI bus, Model 102-EL3, that was 13.7 m (45 foot) in length. All five of the buses purchased were tested to requirements in either FMVSS No. 220 or ECE R.66. A summary of the testing program can be found in the NPRM,

supra

, in section IV.b (79 FR 46100-46102).

41

40

ECE R.66 defines “superstructure” as “the load-bearing components of the bodywork as defined by the manufacturer, containing those coherent parts and elements which contribute to the strength and energy absorbing capability of the bodywork, and preserve the residual space in the rollover test.” “Bodywork” means “the complete structure of the vehicle in running order, including all the structural elements which form the passenger compartment, driver's compartment, baggage compartment and spaces for the mechanical units and components.” (Footnote added.)

41

For further information on the four older buses tested, a detailed discussion of the tests and results are available in the docket entry NHTSA-2007-28793-0019. For further information on the newer vehicle tested, see the test report, “ECE Regulation 66 Based Research Test of Motorcoach Roof Strength, 2000 MCI 102-EL3 Series Motorcoach, NHTSA No.: MY0800,” October 1, 2009, Report No.: ECE 66-MGA-2009-001, which can be found on NHTSA's website.

https://www-nrd.nhtsa.dot.gov/database/aspx/searchmedia2.aspx?database=v_=6797&mediatype=r&r&lowbar;tstno=6797

, Report 8. Step-by-step instructions on accessing the research report can be found in a memorandum in Docket No. NHTSA-2007-28793-0025.

Applicability

NHTSA proposed FMVSS No. 227 to apply to: (a) All new OTRBs, regardless of GVWR; and (b) all new buses other than OTRBs with a GVWR greater than 11,793 kg (26,000 lb), including prison buses and double-decker buses.

42

NHTSA focused on improving the rollover protection of buses with a GVWR greater than 26,000 lb because these were high-occupancy vehicles with an exceptionally high involvement in fatal rollovers. The agency also focused on the buses to which the agency's November 25, 2013 final rule on passenger seat belts applied.

42

Excepted from the NPRM were all school buses, and non-OTRB transit buses and non-OTRBs with perimeter seating.

Performance Requirements

The NPRM proposed performance requirements that the buses must meet when subjected to a dynamic rollover test. The proposed test procedure replicated a rollover crash in a controlled manner. In the proposed test, the bus is placed on a tilting platform that is 800 mm (31.50 inches) above a smooth and level concrete surface. One side of the tilting platform along the length of the vehicle is raised at a steady rate of not more than 5 degrees/second until the vehicle becomes unstable, rolls off the platform, and impacts the concrete surface below with its roof leading edge. The rollover structural integrity test is illustrated below in Figure 1.

BILLING CODE 4910-59-P

ER29DE21.001

BILLING CODE 4910-59-C

NHTSA proposed that the agency could position the bus such that either side (right or left) of the vehicle may be tested for compliance, at the agency's option. The NPRM proposed that a mass of up to 68 kg (150 lb) (ballast) be secured in each designated seating position (DSP) equipped with a seat belt.

The main proposed performance requirements were as follows:

(1) Intrusion into the survival space by any part of the vehicle outside the survival space would be prohibited;

(2) Each anchorage of all seats and interior overhead luggage racks and compartments would be prohibited from completely separating from its mounting structure during movement of the tilting platform or from impact of the bus on the impact surface;

43

43

One reason for the proposal for overhead luggage racks was to further enhance structural integrity. NHTSA thought that, to meet the luggage rack retention requirement, a bus would have to limit its deformation and “racking” in the test. “Racking” means the tilting of the sides of the bus relative to the bus floor. The retention requirement would have applied to luggage racks regardless of their position relative to the survival space. If the rack separated from its mounting it would be a failure, even if the overhead luggage rack did not enter the survival space.

(3) Emergency exits would be required to remain shut during the test, and, after the test, be operable in the manner required under FMVSS No. 217, “Bus emergency exits and window retention and release”; and,

(4) Each side window glazing on the non-impacted side and roof of the vehicle would be required to remain attached to its mounting such that there is no opening that allows the passage of a 102 mm (4 inch) diameter sphere when a force of no more than 22 Newtons (N) is applied to the sphere at any vector in a direction from the interior to the exterior of the vehicle.

The proposed requirements described in paragraphs (2), (3) and (4) are beyond those specified in ECE R.66. The ECE regulation mainly assesses the strength of the “superstructure”

44

in preventing intrusion into the survival space (ECE R.66 uses the term “residual space” rather than survival space). The regulation specifies that the superstructure of the vehicle shall have sufficient strength such that no part of the vehicle that is outside the residual space at the start of the test (

e.g.

, pillars, luggage racks) shall intrude into the residual space during the test.

44

ECE R.66 Revision 1 defines “superstructure” as “the load-bearing components of the bodywork as defined by the manufacturer, containing those coherent parts and elements which contribute to the strength and energy absorbing capability of the bodywork, and preserve the residual space in the rollover test.”

VI. High Level Summary of the Comments

NHTSA received 19 comments on the NPRM from commenters that included large bus manufacturers producing large buses domestically and abroad (Van Hool, TEMSA, Prevost, MCI, Daimler EvoBus, Daimler Trucks/Thomas Built Buses, IC Bus), small (final-stage) manufacturers (Hemphill Brothers (Hemphill), NiteTrain Coach (NiteTrain)), a bus industry group (American Bus Association (ABA)), a

glazing industry group (Enhanced Protective Glass Automotive Association (EPGAA)), motorcoach operators (Greyhound, Hemphill, NiteTrain

45

), the National Transportation Safety Board (NTSB), a research laboratory (Florida A&M University's and Florida State University's Crashworthiness and Impact Analysis Laboratory (CIAL)), a consumer advocacy group (Advocates for Highway Safety (Advocates)), a group of families of passengers involved in six bus crashes, and two private citizens.

45

Both Hemphill and NiteTrain describe themselves not only as manufacturers of “entertainer buses” but also providers of motorcoach transportation services to the entertainment industry, operating the vehicles under contractual arrangements. Hemphill states that the majority of the contractual arrangements for operating the motorcoaches exceed 30 days, with many contracts covering periods of more than one year. Both Hemphill and NiteTrain describe “entertainer buses” as customized vehicles that include kitchens, bathrooms, bedrooms and lounging areas. Passengers are members of entertainment groups, including the lead artists, band members, road managers, stage hands and others, traveling on the road to different performance venues.

There was almost unanimous support for an FMVSS on large bus structural integrity, but differing views on what that standard should require. European bus manufacturers Van Hool and TEMSA opposed the proposed requirements and test procedures that differed from ECE R.66, believing that the ECE R.66 test was appropriate for assessing the strength of the bus superstructure and that subsystems such as seats, overhead racks, emergency exits, and glazing should not be assessed under the proposed standard. ABA concurred with this view. Daimler Trucks/Thomas Built Buses and IC Bus generally supported the intent and requirements of the NPRM but supported incorporating the test procedure of FMVSS No. 220, “School bus rollover protection” (49 CFR 571.220), rather than the test of ECE R.66, for school bus derived buses.

Hemphill and NiteTrain expressed concern about the test burdens on small manufacturers and suggested, as did ABA and Prevost, excluding entertainer buses from the standard. MCI and Van Hool suggested excluding prison transport buses and double-decker buses, respectively.

Consumers and consumer groups believed the proposal was not stringent enough or sufficiently representative of a high speed motorcoach rollover crash involving a bus sliding down an embankment. There were concerns expressed about the sphere test not representing the force imposed by an unbelted passenger thrown against the bus window. EPGAA believed that the proposed requirements should have accounted more for the potential use of advanced glazing as an ejection-mitigation countermeasure.

NTSB and CIAL believed the proposed standard should apply to all non-OTRBs with a GVWR greater than 4,536 kg (10,000 lb), rather than just to non-OTRBs with a GVWR greater than 11,793 kg (26,000 lb). NTSB also suggested the proposed performance requirements should apply to “moon roofs” and to side emergency doors.

No commenter supported a retrofit requirement.

VII. Scope and Purpose of the Rule

NHTSA proposed in the NPRM that the scope of FMVSS No. 227 would be to establish performance requirements for bus rollover structural integrity, and that the purpose of the standard would be to reduce death and injuries resulting from the structural collapse of the bus body structure, the unintended opening of emergency exits, and the detachment of window glazing, seats, and overhead luggage racks.

Van Hool, TEMSA, and the ABA opposed the scope of the proposed requirements and test procedures. The commenters believed that the ECE R.66 test was appropriate for assessing the strength of the bus “superstructure” but that subsystems such as seats, overhead racks, emergency exits, and glazing should not be assessed under FMVSS No. 227. Those commenters, and Prevost, believed that the ECE R.66 rollover test is only designed for, and is capable only of, providing an evaluation of the bus superstructure strength.

ECE R.66 defines “superstructure” as “the load-bearing components of the bodywork as defined by the manufacturer, containing those coherent parts and elements which contribute to the strength and energy absorbing capability of the bodywork, and preserve the residual space in the rollover test.” ECE R.66 requires that the superstructure of the bus must have sufficient strength to ensure that, during and after the rollover test, no part of the vehicle that is outside the survival space at the start of the test intrudes into the survival space during the test.

Agency Response

This final rule adopts the NPRM's proposed prohibition that no part of the bus that is outside the survival space shall intrude into the survival space, both during movement of the tilting platform or resulting from impact of the bus on the impact surface.

46

However, after consideration of the comments, NHTSA has decided not to adopt the NPRM's proposal that each anchorage of an interior overhead luggage rack or other compartment must not completely separate from its mounting structure during movement of the tilting platform or resulting from impact of the bus on the impact surface or that seat anchorages not become dislodged during the test.

46

In response to comments, however, the final rule permits detritus and other debris caused by the impact to fall into the survival space, such as small glazing pebbles or bolts and screws. The objects must not weigh more than 15.0 grams. This issue is discussed in detail below.

Under the NPRM, those proposed prohibitions would have applied even if the luggage rack does not enter the survival space, or the seat anchorages dislodge within the survival space. NHTSA has decided that the primary purpose of this rulemaking is to establish a roof strength and crush resistance standard that improves the resistance of the bus superstructure to deformation and intrusion,

i.e.

, by providing a survival space to occupants in rollovers. The purpose is achieved by prohibiting any structure, such as overhead luggage racks, from intruding into the survival space. By prohibiting overhead luggage racks from impeding into the survival space in the rollover, overhead luggage racks will have to be better anchored to the bus wall than they had been in the past, so that they do not detach and intrude into the survival space in the test. Thus, the proposed luggage rack provision is not needed to provide a survival space, since luggage racks are prohibited from intruding into the survival space. By being securely anchored so that they do not fall into the survival space, luggage racks will be less likely to impede egress in an emergency, or fall and cause head and neck injuries to occupants.

NHTSA has decided against adopting the NPRM's proposal that seat anchorages must not become dislodged during the test. The agency believes the seat anchorage provision is not necessary to achieve a survival space for occupants. NHTSA proposed the requirement for the retention of seat anchorages because of the agency's test of the MY 1991 Prevost LeMirage bus.

47

In the test, anchorages of a seat with a restrained mid-size adult male dummy completely separated from its bus attachment location, allowing the seat to fall across the bus with the restrained dummy attached to the seat. NHTSA believed at the NPRM stage that the

failure of the seat anchorages during the rollover test presented a significant safety risk to restrained occupants in bus rollover events and reduced the effectiveness of seat belts.

47

A summary of the test may be found in the NPRM,

supra

, in section IV.b 79 FR 46100-46102.

However, after considering the comments and other information, NHTSA concludes a specific requirement in FMVSS No. 227 for seat anchorages to remain completely attached is unnecessary for several reasons. First, the seat anchorages in the MY 1991 Prevost LeMirage separated from the bus because the seat was bolted to unreinforced sheet metal of the bus sidewall. In NHTSA's test of the newer MY 2000 MCI bus Model 102-EL3, none of the seats anchorages failed—despite the fact that certain seats were ballasted with either a 150 lb anthropomorphic ballast or with 150 lb steel weights. That is, the seats remained attached even while tested under highly demanding conditions, with the ballasts attached to the seats. This test of the MY 2000 MCI bus demonstrates that bus seat anchorage designs have improved since the MY 1991 and 1992 buses NHTSA tested in its test program.

Second, it is likely the connectivity strength of seat anchorage designs have improved even more since the design of the MY 2000 bus because of the agency's 2013 final rule requiring lap/shoulder belts on all large buses. The final rule requires the lap/shoulder belts to be integral to the bus seats, and that the belt anchorage, together with the seat anchorage to the bus, meet the rigorous strength requirements of FMVSS No. 210, “Seat belt assembly anchorages” (49 CFR 571.210). FMVSS No. 210 requires seat anchorages, attachment hardware, and attachment bolts to withstand loads of 13,345 N (3,000 lb) applied simultaneously to the lap belt portion and the shoulder belt portion of the Type 2 restraint system. The seat anchorages of new large buses meeting FMVSS No. 210 will be reinforced over and beyond the design of a MY 2000 bus, which reduces the risk even further that the seats will detach from the bus structure in a rollover as had been observed in the tests of the MY 1991 and 1992 buses. Thus, adding a specific requirement in FMVSS No. 227 for the seat anchorages to remain completely attached duplicates the seat anchorage retention requirements of FMVSS No. 210.

The agency's bus rollover tests found that glazing panels vacated their window mountings during the rollover. In adopting the proposal that items outside of the survival space must not enter the survival space, this final rule prohibits large panes of glazing falling into the survival space from the non-struck side of the bus and injuring occupants. Strengthening the structure of the bus and glazing mountings to resist the rollover crash forces that act to pop out window glazing is an important “portal improvement” to prevent partial and complete ejection of motorcoach passengers,” as directed by MAP-21 section 32703(b)(2). Further, strengthening the frames is critical to rollover safety if the subject buses employ advanced glazing that mitigate the risk of occupant ejection in rollovers. NHTSA research into advanced glazing as a means of mitigating occupant ejection

48

revealed the need for significant improvement in the structural integrity of motorcoaches before the benefits of advanced glazing materials could be achieved. FMVSS No. 227's survival space requirement will help prevent glazing from popping out or otherwise detaching from its window mount and will help ensure the safety countermeasures are retained in the window frames in a crash.

48

Martec Limited, “Motorcoach Glazing Retention Test Development For Occupant Impact During a Rollover,” August 2006; Docket No. NHTSA-2002-11876-0015. Among other things, this research found that advanced glazing, such as laminate glazing, could pop out of its mounting due to torsional deformation of the structure around the window.

This final rule adopts the requirement for emergency exits to remain closed. This requirement is beyond ECE R.66 but is needed to address concerns relevant to the U.S. NHTSA's bus rollover tests found that emergency exit windows and roof hatches opened during the rollover. NHTSA considers open emergency exits potential safety hazards, as open emergency exits create unsafe ejection portals during a rollover crash. Approximately two-thirds of the fatalities in bus rollover crashes in this country involve occupants ejected from the bus. Reducing the likelihood of ejections through these portals by upgrading latches and hinges will reduce the fatality risk in rollovers and conform to the mandate of MAP-21 section 32703(b)(2).

ABA states that NHTSA placed too much emphasis on preventing unbelted passenger ejection rather than on ensuring the integrity of the body structure. It also states that the FMVSS No. 227 requirements that are not in ECE R.66 replicate the benefits already achieved through the bus seat belt rule.

NHTSA does not agree that FMVSS No. 227 overemphasizes unbelted passengers. Passengers using seat belts, and those that do not, will benefit from the standard by being protected from collapsing bus structures or contact with loose heavy objects. The requirements of FMVSS No. 227 supplement, and do not replicate, the agency's final rule on passenger seat belts. With belted passengers more likely to be retained in the bus interior because of the belts, FMVSS No. 227 improves the protective attributes of the occupant compartment in which they are retained. FMVSS No. 227 will benefit unbelted occupants by helping retain glazing in window frames and providing at least a minimum level of protection against dangerous structural collapse into the occupant compartment. The requirement that emergency exits remain closed during the rollover test increases the likelihood that emergency exits do not become ejection portals during rollover crashes, including crashes involving more than a quarter turn. These requirements will benefit belted and unbelted occupants, as keeping side window exits closed protects against partial ejection of belted occupants and partial and complete ejections of unbelted occupants, including children.

VIII. Applicability of the Rule

NHTSA proposed to apply FMVSS No. 227 to high-occupancy vehicles with an unreasonably high involvement in fatal rollovers, and on which Congress focused in MAP-21.

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NHTSA proposed to apply FMVSS No. 227 to buses to which the agency's November 25, 2013 final rule on passenger seat belts applied.

50

NHTSA's view in the NPRM was that FMVSS No. 227 should apply to those buses with seat belts, so that a survival space could be provided to the belted occupants.

51

49

MAP-21 Subtitle G, the “Motorcoach Enhanced Safety Act of 2012,” defined “motorcoach” as having the meaning given the term “over-the-road bus” in section 3038(a)(3) of TEA-21 (49 U.S.C. 5310 note) but did not include a transit bus or a school bus. Under MAP-21, an over-the-road bus is a bus characterized by an elevated passenger deck located over a baggage compartment.

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NHTSA's seat belt rule applied to all new over-the-road buses regardless of GVWR, including transit buses, prison buses, and perimeter-seating buses). The rule also applied to non-OTRBs that have a GVWR greater than 11,793 kg (26,000 lb), except for non-OTRB transit buses, prison buses, and perimeter-seating buses. The seat belt rule did not apply to school buses.

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The proposed rollover structural integrity requirements applied to all new over-the-road buses regardless of GVWR (except for school buses). The rule also applied to all new non-OTRBs with a GVWR greater than 11,793 kg (26,000 lb), except for school buses, transit buses, and perimeter-seating buses.

The agency received a number of comments relating to the proposed applicability of FMVSS No. 227. Two commenters requested us to include medium-size buses (buses with a GVWR between 4,536-11,793 kg (10,000-26,000 lb), two suggested excluding

entertainer buses, one suggested excluding prison transport buses and another suggested excluding double-decker buses.

a. Medium-Size Buses (Buses With a GVWR of 4,536 to 11,793 kg (10,000-26,000 lb))

In the NPRM, NHTSA proposed not applying FMVSS No. 227 to medium-size buses. NHTSA based the decision on an analysis of crash data for medium-size buses. The agency examined 2000-2009 FARS data showing 42 occupant fatalities in buses with a GVWR between 4,536-11,793 kg (10,000-26,000 lb), of which 24 fatalities were a result of 13 rollover crashes. Over the ten-year period between 2000-2009, medium-size buses were associated with an average of 1.3 rollover crashes per year and 2.4 fatalities per year. In contrast, there was an average of 3.2 rollover crashes annually among large buses (OTRBs and non-OTRBs with a GVWR greater than 11,793 kg (26,000 lb)). These large bus rollover crashes resulted in an average of 11.4 fatalities per year. Among all fatalities occurring in rollover crashes in buses coded in FARS as “cross-country,” “other,” and “unknown” with a GVWR greater than 4,536 kg (10,000 lb), 83 percent were in buses with a GVWR greater than 11,793 kg (26,000 lb).

Two commenters (NTSB, CIAL) disagreed with the agency and commented that NHTSA should include medium-sized buses in the applicability of FMVSS No. 227.

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52

While CIAL focused on paratransit medium-size buses, it requests applying FMVSS No. 227 to all medium-size buses. Further, as its comment does show that paratransit buses have a different safety concern compared other medium-size buses, we are responding to the comment about the whole weight class rather than specifically regarding paratransit buses only.

NTSB Comment

NTSB commented that medium-size buses are often used in a similar fashion as motorcoaches with GVWRs over 11,793 kg (26,000 lb). It disagreed with the data analysis in the NPRM showing that medium-size buses do not have the same crash involvement as OTRBs and non-OTRBs with a GVWR over 11,793 kg (26,000 lb). NTSB stated that FARS has coding issues that may result in undercounting fatalities for the medium-size bus type. It references several crashes that it believes were not counted in the FARS database and suggest that the University of Michigan's Buses Involved in Fatal Accidents (BIFA) database has a more accurate classification of crashes.

Agency Response

NTSB correctly pointed out that we had not included the data that NTSB discussed in its comment. We have updated our FARS data analysis on medium-size buses to include these data. Even with the adjustment, however, our analyses find that medium-size buses do not pose a sufficient safety need to warrant application of FMVSS No. 227 to the buses.

After NTSB commented, NHTSA carefully reexamined and updated FARS data to determine whether the agency under-counted the medium-size bus fatalities. We specifically used FARS data from 2004 to 2018 to ascertain the fatalities attributable to medium-size buses.

FARS has five relevant categories for medium-size buses that are non-OTRBs: “other bus,” “unknown bus,” “van-based bus,” “school bus,” and “transit bus.” Due to the intended scope of this rulemaking, NHTSA focused on only the first three categories.

To assure the dataset was complete, NHTSA also reexamined the FARS body types to check to make sure all medium-size buses were included in the analysis. There had been a change in FARS body codes in 2010. Prior to 2010, van-based buses with GVWRs less than or equal to 10,000 lb were coded as body type code 21, “large van.” In 2010, body code 55 was added to the FARS coding manual (van-based bus with a GVWR greater than 4,536 kg (10,000 lb)). With that change, NHTSA considered whether, for the FARS data files before 2010, it was possible that some van-based buses with a GVWR greater than 4,536 kg (10,000 lb) were classified under body code 21. Consequently, NHTSA searched for crashes involving body code 21 with a GVWR greater than 10,000 lb and with a bus use codes of “intercity,” “charter/tour,” “transit/commuter,” “shuttle”

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to see if there were any other rollover crashes involving types of vehicles that could be considered “medium-size buses.” We identified three rollover crashes, as shown in Table 9 below.

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FARS has bus use categories of not a bus, school, intercity, charter/tour, transit/commuter, shuttle, modified for personal/private use, not reported, and unknown. Among these bus use categories, the large vans that were used as charter/tour, intercity, commuter, and shuttle were relevant to this rulemaking. Therefore, only the large vans with these bus use codes were included.

Table 9 below shows the number of medium-size bus crashes with a fatality, over a fifteen-year period.

Table 9—Fatal Bus Occupant Crashes of Medium-Size Buses (GVWR 10,000 lb to 26,000 lb) That are Non-OTRBs, by the Body Type and the Crash Mode

[FARS 2004-2018]

Body type

Rollover

Frontal

Side

Rear

Total

Other bus

7

8

3

1

19

Unknown bus

3

2

0

0

5

Van-based bus

9

20

8

2

39

Large van (used as intercity, tour, commuter, or shuttle buses)

3

6

5

2

16

Total

22

36

16

5

79

The data show that there were 79 fatal medium-size bus crashes between 2004 and 2018, of which 22 of the 79 crashes were rollover crashes. For the purposes of determining the safety need of applying FMVSS No. 227 to medium-size buses, NHTSA will focus only on rollover crashes, as the harm the standard is intended to address, and the countermeasures that will be installed pursuant to that harm, only result from rollovers.

Table 10, below, shows the total number of medium-size bus fatalities attributable to various crash types.

Table 10—Fatalities in Medium-Size Buses by Body Type, Crash Mode, and Occupant Type

[FARS 2004-2018]

Body type

Rollover

Driv

Pass

Front

Driv

Pass

Side

Driv

Pass

Rear

Driv

Pass

All types

Driv

Pass

Total

Other bus

1

18

5

7

1

2

0

1

7

28

35

Unknown bus

0

6

1

1

0

0

0

0

1

7

8

Van-based bus

4

7

12

28

1

8

1

1

18

44

66

Large van (used as intercity, tour, commuter, or shuttle buses)

1

8

3

7

0

7

1

2

5

24

29

Total (above)

6

39

21

43

2

17

2

4

31

103

134

For the three relevant medium-size bus types and the large vans used as buses, there were 45 total fatalities (6 driver fatalities and 39 passenger fatalities) in rollover crashes for the fifteen-year period. Over the 15-year period 2004-2018, there were an average of 1.5 fatal medium-size bus rollover crashes, with an average of 3.0 bus occupant fatalities per year.These values are small compared to those of large buses. According to data from FARS 2004-2018, there was an average of 3.7 fatal rollover crashes involving large buses (GVWR greater than 11,793 kg (26,000 lb)) (including OTRBs), resulting in an average of 11.7 occupant fatalities per year. There are significantly higher average rates of annual fatal crashes and fatalities for large buses compared to medium-size buses.

While the average rates of annual fatal crashes and fatalities for large buses are significantly higher than those of medium-size buses, the fleet size of large buses is significantly smaller than that of medium-size buses. There are an estimated 2,200 large buses (GVWR greater than 11,793 kg (26,000 lb)) (including OTRBs) produced annually, compared to approximately 15,000 buses with a GVWR between 4,536-11,793 kg (10,000-26,000 lb) produced annually.

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Table 11, below, summarizes these figures.

54

Evaluation of the Market for Small-to-Medium-Sized Cutaway Buses, Federal Transit Administration Project#: M1-26-7208.07.1, December 2007, available at

https://www.transit.dot.gov/sites/fta.dot.gov/files/docs/AnEvaluationofMarketforSmalltoMediumSizedCutawayBuses.pdf

, last accessed November 04, 2016.

These data mean that there is a considerable disparity between the fatal rollover crash involvement for large buses versus medium-size buses. Not only are large buses involved in more than twice as many rollover crashes on average annually, they also have about four times the number of occupant fatalities annually in rollover crashes than medium-size buses. Further, taking into consideration the almost seven-fold difference in annual production between large buses and medium-size buses (the annual production of large buses is about 1/7th of the annual production of medium-size buses), the safety need for FMVSS No. 227 is substantially higher for large buses than for medium-size buses.

Table 11—Summary Statistics for Fatal Rollover Crashes and Occupant Fatalities for Large Buses (Including all OTRBs) and Medium-Size Buses

[From 2004 to 2018 (FARS)]

Bus size

Avg. annual rollover

crashes

Avg. annual rollover

fatalities

Avg. annual fleet sales

Large Bus (greater than 26,000 lb GVWR) and all OTRBs

3.7

11.7

2,200

Medium-Size Bus (GVWR of 10,000-26,000 lb)

1.5

3.0

15,000

With regard to the question whether there is a safety need to apply FMVSS No. 227 to medium-size buses, NHTSA's answer is no, the data do not show such a need at this time. The difference between the fatal rollover crash involvement between large and medium-size buses may be attributable to medium-size bus designs (

e.g.

, medium-size buses may have a lower center of gravity compared to heavy buses, affecting crash involvement and/or severity, or have better vehicle controllability for a variety of reasons), or may reflect a difference in how the buses are used. Regardless, the data dissuade NHTSA from applying FMVSS No. 227 in a one-size-fits-all manner to all buses. NHTSA concludes there is not a substantial safety need to apply the standard to medium-size buses.

NHTSA does not concur with NTSB's view that the BIFA database provides more relevant statistics than NHTSA's database. The BIFA database only includes data up to 2010, and so more recent crash data are not available. Since 2010, NHTSA has improved the accuracy of its crash data collection on buses and has expanded the bus category to include van-based buses. NHTSA's updated analysis using the FARS data files more accurately includes the mid-size bus crash information.

NTSB stated that the statistics from BIFA indicate that 128 medium-size buses were involved in fatal crashes, resulting in 58 occupant fatalities between 2000-2009. This information does not show whether these crashes were rollover crashes (the crashes relevant to this rulemaking), or whether the 58 occupants were killed in rollovers. Despite the lack of specific data about the nature and severity of the crashes, NHTSA undertook an analysis assuming that all the crashes NTSB referenced were rollover crashes, and that all 58 fatalities were attributable to rollovers. NHTSA found that, even with this assumption, the data still show a large disparity between the rollover crashes associated with large buses versus medium-size buses. Even if all 58 fatalities were attributable to rollover crashes, such crashes would contribute

to, on average, 5.8 deaths annually (58 fatalities/10 years). In this hypothetical scenario, large buses would still be associated with 1.3 times the number of fatalities compared to medium-size buses each year—while the annual production of large buses would continue to be around 1/7th of the annual production of medium-size buses. Thus, even when factoring in the crash data suggested by NTSB and making assumptions about the data that likely includes more crashes and fatalities than actually occurred in medium-size buses, the data again show an absence of a safety need for applying FMVSS No. 227 to medium-size buses.

For the reasons above and in the NPRM, NHTSA declines to extend FMVSS No. 227 to medium-size buses.

CIAL Comment

CIAL argued that the proposed standard should apply to medium-size paratransit buses because buses meeting the proposed standard would be safer for passengers. It indicated it has been researching medium-size paratransit buses designed to meet FMVSS No. 220

55

and found that buses meeting FMVSS No. 220 fail a dynamic rollover test based “on the concept of survival space.” The commenter stated that six buses it tested showed a failure mode “in which a weak frontal structure allowed for excessive deformation to occur in the front portion of the bus body.”

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The requirements in FMVSS No. 220 apply to school buses. The test in FMVSS No. 220 places a uniformly distributed vertical force pushing directly downward on the top of the bus with a platen.

Agency Response

NHTSA declines to make the suggested change. CIAL's comment did not provide a basis to conclude there is a safety need to adopt the FMVSS No. 227 test for medium-size buses. (See response, above, to NTSB on this issue.) CIAL states that its evaluation using finite element models of medium-size paratransit buses shows that paratransit buses meeting FMVSS No. 220 failed to meet a “survival space” criterion of a Florida state vehicle standard. While CIAL's comparison of the performance of paratransit buses under the requirements in FMVSS No. 220 and ECE R.66 was based on simulations, NHTSA conducted the physical tests specified in the two standards on the same large bus models. NHTSA's rollover testing of motorcoaches indicated that large buses that did not meet the ECE R.66 survival space requirement also failed the FMVSS No. 220 requirements.

Additionally, as noted earlier, over the 15-year period 2004-2018, there were an average of 1.5 fatal medium-size bus rollover crashes, with an average of 3 bus occupant fatalities per year. These data apply to all medium-size buses and therefore, the average annual number of rollover crashes and fatalities associated with medium-size paratransit buses would be extremely small. The fact that the vehicles did not meet the survival space criterion is not commensurate with a need to apply FMVSS No. 227 to the vehicle type at the FMVSS level. We decline to make the requested change, for the reasons provided above and in the NPRM.

b. Large Buses

Entertainer Buses

NHTSA proposed to apply FMVSS No. 227 to all OTRBs as they were defined in MAP-21. In doing so, NHTSA intended to cover all the buses Congress directed the agency to address in MAP-21, regardless of GVWR.

Comments Received

Hemphill and NiteTrain, manufacturers and operators of over-the-road entertainer buses, expressed concern about the test burdens on small final-stage manufacturers of these vehicles, and suggested excluding entertainer buses from the standard. Prevost, a manufacturer of both complete motorcoaches and incomplete vehicles (“shells”), also commented in favor of excluding entertainer buses. According to Hemphill and NiteTrain, their entertainer buses are built from incomplete bus shells purchased from Prevost. The shells consist of the window exits, roof exits, sidewall, and roof structure.

NiteTrain and Hemphill stated that since they do not alter the safety structure of their purchased motorcoach shells, any compliance with the new standard should be the responsibility of the shell manufacturer. ABA commented that NHTSA should consider entertainer buses a distinct type of motor vehicle and decide “on a case-by-case basis, the extent to which each element of the motorcoach safety requirements should be made applicable.”

Agency Response

NHTSA has decided not to apply FMVSS No. 227 to over-the-road perimeter-seating buses. The agency's decision to scale back the scope of FMVSS No. 227 is based on an analysis of safety need, and not on a finding that small manufacturers cannot certify compliance with the standard. There are ways small manufacturers may certify to FMVSS No. 227 that would not impose undue burdens on the manufacturers. For a discussion of those options, see the August 6, 2014 NPRM preceding this final rule (79 FR 46116-46117), and the Regulatory Flexibility Act analysis below in this final rule.

Instead, NHTSA has reassessed the need to apply FMVSS No. 227 to OTRBs with perimeter seating after considering that non-OTRBs with perimeter seating are excluded from the standard. NHTSA does not find a reason to distinguish between OTRB with perimeter seating and non-OTRB with perimeter seating, when the safety data indicate no relevant differences between the vehicles based on safety need. OTRB with perimeter seating do not present a greater risk of injury due to the failure of the structural integrity of the buses compared to non-OTRBs with perimeter seating.

Section 32703(a) of MAP-21 mandated NHTSA to prescribe a seat belt rule for lap/shoulder belts for motorcoaches (

i.e.

, which MAP-21 basically defined as over-the-road buses, except transit buses and school buses) and did not provide NHTSA discretion in applying the requirement. Thus, the 2013 seat belt rule issued pursuant to section 32703(a) applied uniformly to all over-the-road buses. NHTSA also applied the rule to non-OTRBs, but had discretion to draw distinctions among buses in that bus category, as appropriate. NHTSA drew on that discretion to design a rule that excluded non-OTRBs with perimeter seating from the belt requirement, based on an absence of a safety need for the belts.

NHTSA drafted the FMVSS No. 227 NPRM preceding this final rule to apply the proposed structural integrity requirements to the buses that were subject to the lap/shoulder belt requirements adopted by the 2013 MAP-21 final rule. The agency believed that there was a need to ensure enhanced structural integrity of the interior of buses subject to the seat belt rule, to better protect the restrained occupants who, due to the belts, will be retained in the bus interior.

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The NPRM excluded from proposed FMVSS No. 227 perimeter seating buses, but not if they were OTRBs.

57

56

79 FR 46096, col. 1.

57

The proposed definition of “perimeter-seating bus” is “a bus with 7 or fewer designated seating positions rearward of the driver's seating position that are forward-facing or can convert to forward-facing without the use of tools and is not an over-the-road bus.” (S3.) NHTSA excluded perimeter-seating buses that were not over-the-road buses from the seat belt rule because perimeter-seating buses are often used in shuttle operations.

However, after considering the comments, NHTSA has decided not to apply FMVSS No. 227 to perimeter-seating buses as a class. In the seat belt final rule, NHTSA applied the belt requirement to OTRBs with perimeter seating, and not to non-OTRB with perimeter seating, because of a statutory mandate to require the seat belts in

all

OTRBs. There is no such mandate about the applicability of FMVSS No. 227. NHTSA has discretion under MAP-21 (section 32703(b)) to determine whether a rollover structural integrity standard and an anti-ejection portal improvement standard meet the requirements and considerations of section 30111(a) and (b) of the Safety Act.

58

After considering section 30111(a) and (b), NHTSA has decided it would not be appropriate to distinguish between perimeter-seating buses depending only on whether they are OTRBs or not.

58

NHTSA is authorized under the Vehicle Safety Act to issue motor vehicle safety standards that “shall be practicable, meet the need for motor vehicle safety, and be stated in objective terms” (49 U.S.C. 30111(a)). When prescribing a motor vehicle safety standard, NHTSA considers,

inter alia,

relevant available motor vehicle safety information, whether a standard is reasonable, practicable, and appropriate for the particular type of motor vehicle or motor vehicle equipment for which it is prescribed, and the extent to which the standard will carry out the purpose and policy of the Act,

i.e.

, reduce traffic accidents and deaths and injuries resulting from traffic accidents (49 U.S.C. 30111(b)).

NHTSA developed its motorcoach safety plan to protect the public against unreasonable risk of death or injury in high-occupancy vehicles.

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In the Executive Summary in NHTSA's 2013 seat belt final rule, NHTSA stated: “One of the guiding principles NHTSA considers in determining the priorities of our rulemaking projects is to protect the public against unreasonable risk of death or injury in high-occupancy vehicles. In 2007, NHTSA published a comprehensive plan to research improvements to bus safety, entitled, ‘NHTSA's Approach to Motorcoach Safety.’ ” [Footnote omitted.] In contrast, perimeter-seating OTRBs are low-occupancy vehicles compared to conventional inter-city buses that have primarily forward-facing seating. NHTSA has decided to exclude both OTRBs with perimeter-seating and non-OTRBs with perimeter-seating from this final rule, based on an absence of a safety need to include the buses. It is reasonable not to distinguish between the two kinds of perimeter-seating buses in applying the standard to the vehicles because of an absence of reasons to distinguish. This final rule treats both kinds of buses with perimeter seating (OTRB and non-OTRB) the same under FMVSS No. 227.

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78 FR 70416, November 25, 2013. The preamble also makes repeated reference to “high-occupancy” buses in its analyses of crash data involving the subject buses.

It should be noted that Hemphill and NiteTrain indicate that they obtain a bus “shell” from an incomplete vehicle manufacturer, such as Prevost.

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Prevost manufactures both complete motorcoaches and incomplete vehicles (“shells”). The agency believes that, following establishment of this FMVSS No. 227, Prevost will offer for sale in the U.S. incomplete vehicle shells that meet the structural integrity requirements of ECE R.66 (the standard on which FMVSS No. 227 is based), because most of their final-stage manufacturer customers will produce buses that are subject to FMVSS No. 227. For customers that produce buses that are excluded from FMVSS No. 227, for liability and competitive marketing reasons, it would make little commercial sense to offer shells that do not meet ECE R. 66 to customers, or for customers to buy such shells. Thus, even if perimeter-seating buses are excluded from FMVSS No. 227, manufacturers will likely produce buses using these ECE R.66 shells, which will result in vehicles that provide significantly improved structural integrity in a rollover crash. When the bus superstructure is strengthened to meet FMVSS No. 227 there will be less deformation of the bus structure and reduced torsional loads on interior structures, such as partitions, and reduced risk of intrusion into the occupant space. This means that perimeter-seating buses, even though excluded from the standard, will provide enhanced structural integrity in a rollover. Hemphill commented that partitions will “add support to the roof of our coaches and significantly increase the roof's integrity” and will “significantly reduce any intrusion into the survival space” in a rollover. While the commenter did not provide data or evidence to support its claim, NHTSA concurs that minor modifications to the vehicle structure, such as by installation of partitions, will not degrade the integrity of the superstructure of the bus, and that even these perimeter-seating buses will provide protection against roof collapse in a rollover.

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Incomplete vehicle manufacturers such as Prevost are large manufacturers.

Prison Transport Buses

The NPRM proposed to apply FMVSS No. 227 to prison transport buses (78 FR 70416). MCI, a manufacturer of prison transport buses, disagreed with this proposal. MCI expressed concern about the need to partition these buses to provide cells, believing that each customer's unique cell configuration could affect the test results of the standard. MCI states it would not be practicable to fulfill a one-of-a-kind bus order by building a second bus for testing to meet MCI's certification responsibilities.

Agency Response

NHTSA agrees to exclude prison buses from FMVSS No. 227 but not for the reason given by MCI. Due to the nature of the vehicle type, prison vehicle interior configurations/partitions may vary considerably. However, NHTSA does not require the kind of certification burden MCI describes. A manufacturer does not have to build a replicate vehicle to test to enable the manufacturer to certify compliance with the standard. A discussion of various certification methods available to manufacturers can be found in the August 6, 2014 NPRM preceding this final rule (79 FR 46116-46117), and in the Regulatory Flexibility Act analysis below in this final rule.

NHTSA is excluding prison buses because the FMVSS No. 227 is not appropriate for the bus type. The agency does not know how many prison buses are manufactured each year, but does not believe there is a substantial number of such vehicles produced. Regardless of the number of vehicles produced, bus superstructures sold in the U.S. are likely to be strengthened to meet FMVSS No. 227 after this final rule becomes effective. With the strengthened superstructures, there will be less deformation of the bus structure and reduced torsional loads on interior structures, such as partitions. Thus, the agency has not found justification to apply FMVSS No. 227 to prison buses, as minor modifications to the vehicle structure, such as by installation of partitions, are unlikely to affect the structural integrity of the vehicles.

Double-Decker Buses

The NPRM proposed to apply FMVSS No. 227 to double-decker buses. Buses with open-roof sections would not have the open section assessed for compliance but the closed-roof sections would be. Double-decker buses with closed-roof sections on the lower and top levels would have both levels assessed for compliance. Since we saw no difference in the potential safety risks of double-decker buses and other large buses covered under our proposal, we proposed applying FMVSS No. 227 to the bus type.

Comments Received

NTSB and Coach USA (a large motorcoach operator) supported applying FMVSS No. 227 to double-decker buses. NTSB stated it would be appropriate to test the portions of the bus where bus structure could intrude on the vehicle occupants. Coach USA supported applying the same requirements to lower/enclosed sections of open-top double-decker buses, and stated that its double-decker buses already comply with the ECE R.66 test. In contrast, Van Hool stated that in Europe ECE R.66 can be applied to double-deckers only at the request of the manufacturer and referenced a document to argue that the number of fatalities that are attributable to double-decker buses is lower than those attributable to other buses.

Agency Response

This final rule applies FMVSS No. 227 to double-decker buses as proposed. Double-decker buses are being used for intercity/interstate transport of large numbers of passengers.

61

61

See

e.g.,

Megabus website,

http://us.megabus.com/, last accessed October 24, 2016

.

We do not concur with Van Hool that there should not be a safety concern with double-decker buses. The document that Van Hool referenced to support its view consists only of meeting notes from a UN ECE informal working group meeting on ECE R.66.

62

The meeting notes stated that a representative from Spain presented information about bus crashes, but the notes did not include statistics about double-decker buses. Further, the notes included a point made by a person from the International Road and Transport Union expressing concern that the increased mass of the superstructure of a double-decker bus above the vehicle's center of gravity might suggest that the double-decker bus should be subject to the ECE R.66 requirements. We do not see any information in the meeting notes that suggested that the safety risk is lower for these types of buses.

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https://www.unece.org/fileadmin/DAM/trans/doc/2008/wp29grsg/GRSG-95-07e.pdf

(last accessed Feb-23-2017).

Further, we believe that the design characteristics and physics of double-decker buses suggest that double-decker buses are at least as susceptible to the rollover crash risk as the other buses covered under this final rule. Double-decker buses can have GVWRs fifteen to twenty percent greater than single-deck OTRBs.

63

A Swedish study

64

on occupant fatalities in bus crashes concluded that—

63

Van Hool TX Luxury Touring Coach GVWRs are 50,700 lb (40″ vehicle length) and 54,000 lb (45″ vehicle length). Van Hool TD925 double-decker buses are GVWR 62,000 lb (45″ vehicle length). Vehicle data from

https://www.abc-companies.com/,

last accessed October 24, 2016.

64

Albertsson, Pontus; Occupant Casualties In Bus And Coach Traffic; 2005; ISBN 91-7305-829-7.

The height of a double-deck vehicle may be 60-80 [centimeters] higher than a corresponding single deck vehicle. In case of a rollover with a double-deck vehicle, the greater [the] distance from the [center] of gravity in the upper compartment[,] the greater [the] increase of the rotation velocity. This, in turn, will increase the [ground] impact [leading to] greater risk for injuries as a consequence.

Thus, the available information does not support Van Hool's contention that there is little crash risk associated with double-decker buses. While the agency seeks to harmonize with ECE regulations to the extent possible, we believe applying FMVSS No. 227 to double-decker buses will meet a safety need in this country. According to Coach USA, its double-decker buses already meet the ECE R.66 requirements, which illustrates the practicability of the buses” meeting FMVSS No. 227.

This final rule makes a slight clarification in the regulatory text of FMVSS No. 227 relating to double-decker buses. The standard would not apply to a level of a bus that does not have a permanent roof over the level, such as the upper level of a double-decker bus that does not have a permanent roof over the upper level. However, a double-decker bus that is open-top in the rear half of the bus but permanently closed-top for the front half of the bus is subject to the requirements of FMVSS No. 227 for the front half of the top of the bus (as well as for the entire enclosed lower section of the bus).

IX. School Bus Derivative Buses

Daimler Trucks North America (DTNA)

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and IC Bus, LLC (IC Bus) manufacture school and commercial buses and certify the vehicles to FMVSS No. 220, “School bus rollover protection,” and FMVSS No. 221, “School bus body joint strength.” The commenters suggest that NHTSA permit buses meeting FMVSS No. 221 the option of meeting FMVSS No. 220 rather than FMVSS No. 227. They state that the buses are similar in appearance to school buses but are sold for non-school related purposes. The commenters contend that the operating environment for these buses is closer to that of school buses than intercity buses and that the vehicles should be subject to the school bus safety standards for rollover protection (FMVSS No. 220) and joint strength (FMVSS No. 221) rather than FMVSS No. 227.

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DTNA states that it manufactures school buses under the Thomas Built Bus brand.

Agency Response

We agree with the commenters and have excluded school bus derivative buses from FMVSS No. 227. This is because the buses already provide a survival space by meeting FMVSS No. 220, “School bus rollover protection,” and do not need to meet the requirements of FMVSS No. 227.

FMVSS No. 227 defines “school bus derivative buses” in a manner reflecting that the buses are built on a school bus platform for sale in the U.S. The buses have safety systems that are identical to school buses regarding their fuel systems, bus body joint strength, emergency exits and roof crush resistance. The vehicles could be certified as meeting the FMVSSs for “school buses” if they had seating systems meeting FMVSS No. 222, “School bus seating and passenger protection” (49 CFR 571.222), and school bus lights and stop arms meeting FMVSS No. 108 and No. 131, respectively. NHTSA is excluding the buses to avoid redundancy in the FMVSSs. Thus, the definition is designed to exclude only vehicles that could be certified to the school bus FMVSSs and not other large buses.

DTNA and IC Bus argue that their school bus derived commercial buses operate under conditions more similar to those of school buses than OTRBs. The “applications” in which the commercial buses are used are described by DTNA as “church activity, retirement community, college campus, boys and girls club, parks and recreation department and airport shuttles.” IC Bus echoes that description and adds “support of emergency responders.” NHTSA agrees that these applications describe usage that is more local in nature than that of intercity OTRBs. NHTSA recognizes, however, that once purchased, operators of the vehicles could use school bus-derivative buses in ways other than that described by DTNA and IC Bus, so in analyzing the commenters” suggestion NHTSA must consider the likelihood that the buses may not be used like school buses.

It is a fact that FMVSS No. 220 has a record of rollover safety in school buses. The standard has been applied to school buses since 1977. School bus derivative buses are already manufactured to meet the school bus roof crush resistance

requirements in FMVSS No. 220. NHTSA believes these buses already have improved roofs and roof supports that substantially improve the resistance of the roofs to deformation and intrusion compared to buses that do not meet FMVSS No. 220.

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To avoid redundancy in the FMVSSs, this final rule permits these buses the option of meeting FMVSS No. 220 when tested in accordance with the test procedures of FMVSS No. 220, instead of the ECE R.66-based rollover test requirements of FMVSS No. 227.

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In addition, as DTNA and IC Bus point out, the vehicles also meet FMVSS No. 221, which adds to the structural integrity of the vehicles. The purpose of FMVSS No. 221 is to reduce deaths and injuries resulting from the structural collapse of school bus bodies in crashes.

The agency is not permitting buses other than school bus derivative buses to meet FMVSS No. 220. Buses other than school bus derivative buses have been designed such that they have a higher center of gravity and/or utilize larger windows than school buses. These characteristics can lead to a higher incidence of occupant ejections during rollovers. Thus, the dynamic rollover test in ECE R.66 affords the agency an opportunity to set a minimum level of performance for the ejection-mitigating features of non-school bus derivative buses, such as emergency exits closure and side window glazing retention during a rollover crash.

X. Performance Requirements

The NPRM proposed performance requirements that buses must meet when subjected to a tilt rollover test. In the proposed test, the bus is placed on a tilting platform that is 800 mm (31.50 inches) above a smooth and level concrete surface. One side of the tilting platform along the length of the vehicle is raised at a steady rate of not more than 5 degrees/second until the vehicle becomes unstable, rolls off the platform, and impacts the concrete surface below with its roof leading edge. The major points of this testing method involve a quarter-turn roll of the bus onto its side (so that it strikes the top corner of the bus superstructure on a rigid surface) and ballasting the vehicle to simulate the load that the bus would be carrying in a rollover crash. This test creates a high-severity test condition that encompasses the majority of real-world bus rollovers.

a. Severity of the Rollover Test

EPGAA, Advocates, the families of bus crash victims (the families), and Ms. Stoos, express concern that the proposed test evaluation is not severe enough to replicate the conditions of real-world bus rollovers. The families and Advocates state that the rollover test should include: Vehicle rollovers greater than 90 degrees (one quarter roll); high vehicle speed prior to rollover; embankments; and impacts that may occur after the rollover. Advocates references a 2007 glazing retention test development study commissioned by NHTSA and Transport Canada to illustrate its point (“Motor Coach Glazing Retention Test Development For Occupant Impact During A Rollover,” Martec Technical Report # TR-06-16, Rev 4, August 2006 (“Martec study”)

67

).

67

Docket No. NHTSA-2002-11876-0015.

Agency Response

NHTSA does not agree with the commenters' argument that FMVSS No. 227's test is not a reasonable representation of a severe rollover crash. As discussed below, research papers, test reports, simulation analyses, and reports on the efficacy of the ECE R.66 test support the implementation of the test.

FMVSS No. 227's test is highly stringent, accounting for the potential real-world rollover crash forces that are imparted on the bus superstructure in a rollover crash. The test creates a force near the top corner of the bus in the transition from the sidewall to the roof. This application of force is representative of a bus rolling over into a drainage ditch along a highway; however, in the FMVSS No. 227 test, the bus strikes a hard surface that is more rigid than the typical earthen drainage ditches along the roadside. The hard surface results in the energy from the rollover being absorbed by the bus and not shared between the bus and the ground. This hard surface contact makes FMVSS No. 227's rollover test more stringent than similar rollovers into earthen embankments. Matolcsy, M. (2007), “The Severity of Bus Rollover Accidents,” 20th International Technical Conference for the Enhanced Safety of Vehicles, Paper 989, Lyon, France.

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The test also gives the agency a repeatable, reproducible, and practical method to evaluate bus structural integrity during rollover crashes.

68

Available at:

https://www-esv.nhtsa.dot.gov/Proceedings/20/07-0152-O.pdf

.

It can appear to the eye that crashes involving multiple quarter-turn rolls along the ground are more severe than a single quarter-turn rollover onto rigid pavement that ends instantly, all other things being equal. The significant difference is that the multiple quarter-turn roll loads an entire side, then the roof, then the other side, next the wheels/suspension/floor, and so on until the bus comes to a rest. The multiple quarter-turn rollover dissipates the crash energy across major portions of the vehicle structure over a relatively long duration. The vehicle structure in a multiple quarter-turn crash is not managing or absorbing all of the crash energy at once. Single quarter-turn rollovers, in which the crash forces are reacted over a short duration by relatively weak localized components of the vehicle structure, require the entire vehicle structure to be stronger. Therefore, the more stringent rollover test is one in which the energy of the crash is applied instantaneously, such that the vehicle needs to manage and absorb all the energy applied at the same time.

The demanding nature of the ECE R.66 test incorporated into FMVSS No. 227 is discussed at length in the 2007 report, which evaluated the sufficiency of the test for adoption into R.66.

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The report's author notes that early work on ECE R.66 considered different types of rollover scenarios during deliberations to “find an appropriate standard approval rollover test.” For the issue of conducting a test with multiple turns (

i.e.

, the bus rolling more than a quarter-turn), the study concluded that the ECE R.66-based test imparts more loads on the bus superstructure than other potential tests that included multiple turns. This was found even though the tests with multiple turns began with a bus raised higher from its final end of test resting place—

i.e.

, the other tests began with greater potential energy than the ECE R.66-based test.

69

Matolcsy, M. (2007),

supra

.

Figure 3, below, shows the three rollover tests that were analyzed during development of ECE R.66.

ER29DE21.002

The study

compared the quarter-turn ECE R.66 test to other tests in which the bus traveled a greater distance during the test and rolled multiple times. The research conducted a series of tests under three test scenarios using the same bus type. In the end, the research showed test “c,” which is essentially ECE R.66, produced results that imparted the greatest loads on the bus superstructure. The test series further showed that bus reinforcements to provide survival space in test “b” needed further reinforcement to provide sufficient survival space in test “c.” From these data, it was found that, while a test could simulate a crash with more total energy (

e.g.

, test conditions “a” and “b” under which the bus begins the test with higher potential energy), the long dissipation of that energy over multiple rolls during the crash significantly reduces the damage imparted to the bus superstructure during the test.

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Id.

NTSB and Advocates request that the agency consider a test involving more than a quarter-turn rollover. The commenters did not elaborate on how many more turns of a vehicle rollover they would like the agency to adopt. The agency has no data on the number of quarter-turns that occur in a bus rollover since the FARS database does not capture that crash detail. Nonetheless, the Matolcsy report,

supra

, explains how buses developed to meet the requirements of ECE R.66 have maintained survival space when those buses have experienced rollovers beyond a quarter-turn and down embankments. This information suggests that FMVSS No. 227 will lead to buses capable of providing bus passengers with a survival space and lowered risk of ejection during rollover crashes greater than a quarter-turn.

The Matolcsy report provides additional examples of real-world improvements manufacturers have made to buses in response to ECE R.66 requirements, including photographs of how bus interior compartments looked post-crash before and after application of ECE R.66 to the vehicles. A bus that was not designed to comply with ECE R.66 experienced structural collapse in a rollover crash with one and a half full 360 degree rolls down a 6-meter embankment similar to the one depicted above in Figure 3(b). In contrast, a bus designed to meet ECE R.66 requirements was able to maintain adequate survival space in a rollover crash with two and a quarter full 360 degree rolls down a 9-10 meter embankment similar to the crash depicted in Figure 3(b) above.

In its comments, Advocates references a research project on motorcoach window glazing in which the research used finite element (FE) models to compare the loads on the bus structure in different simulation tests where the bus carried different lateral speeds into its crash with the impact surface.

71

The simulation scenarios in the research included: (1) No lateral speed with 800 mm drop (replicating ECE R.66), (2) 30 kilometers per hour (km/h) lateral speed with 400 mm drop, and (3) 30 km/h lateral speed with 800 mm drop.

72

71

See

Comment from the Advocates for Highway Safety, Docket No. NHTSA-2014-0085-0016, page 5 and 6. The comment references the 2007 NHTSA report,

National Motor Coach Glazing Test Development for Occupant Impact during a Rollover

. (NHTSA-2002-11876).

72

See

Martec Technical Report # TR-06-16; “Motor Coach Glazing Retention Test Development For Occupant Impact During A Rollover,” (Joint NHTSA and Transport Canada Program; Final Report); Docket No. NHTSA-2002-11876-0015.

Advocates refers to a statement by the researchers that the ECE R.66 test is not the most stringent test condition. NHTSA notes that the statement reflected only a preliminary finding of Phase I of the study and was later corrected.

73

The preliminary results in Phase I were refined in Phase II of the study. After improving their analysis methodology and conducting the simulation again in Phase II, the researchers conclude that the ECE R.66 test is the more stringent test when compared to tests that incorporated a lateral speed.

74

As can be seen in the Table 12 data, the ECE R.66 rollover produced higher rollover contact forces than rollover simulations with the ECE R.66 drop height and an initial lateral velocity.

73

The authors stated that the models used for the first phase were not detailed and were “only expected to provide rough-order-of-magnitude roof/ground [contact] forces.”

74

Id

.

Table 12—Comparison of Roof Impact Forces

75

Rollover Scenario

No. 1 (ECE R.66)

Phase I

Current

No. 2 (400 mm)

Phase I

Current

No 3. (800 mm)

Phase I

Current

Contact Surface

Roof perimeter

Window Posts

Roof Perimeter & Window Posts

Window posts

Roof Perimeter

Window Posts.

Peak contact Force (N)

4,065,900

2,831,593

4,538,964

2,468,656

3,920,160

2,696,370.

Average Impact Force (N)

1,481,100

1,219,995

2,271,342

891,627

1,960,137

1,149,529.

When

a bus traveling at highway speeds tips and begins a multiple-turn roll, the energy in the crash will not be completely transferred to the vehicle structure at the first impact. A significant portion of the energy will go towards sustaining the rolling motion of the bus. Thus, while the vehicle would sustain more impacts during this extended rollover crash, the loads on the superstructure would be lower than the ECE R.66-based test. Further, even if the bus turned only once at highway speed, landed on its side, and slid on the side, the single impact at highway speed would load an entire side of the bus structure, rather than just a corner of the bus superstructure. This flat-faced, wide application of the load dissipates the energy and enables the bus to better withstand the load than the more stringent concentrated load application of FMVSS No. 227. The friction from the sliding of the bus on the surface of the ground also dissipates the kinetic energy of the crash over a longer period—further reducing the load on the vehicle superstructure In short, FMVSS No. 227 presents a severe real-world application of crash loads on the superstructure, and does so in a controlled, objective manner appropriate for an FMVSS compliance test.

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Id

., table from report, page 14.

Advocates also discuss a crash variation where the bus may hit an embankment or other “vertical surface” type object. This crash variation may or may not increase the total energy to be dissipated during the crash, but the load concentration may change. However, even with different potential objects loading the structure, we believe that the loads to which the superstructure is subjected might be similar in some respects to the loading to which the superstructure is exposed when tested under FMVSS No. 227. While no embankment or other “vertical surface”-type object is a part of the test, the vehicle superstructure's loading during the test is akin to the concentrated force that is applied when striking a “vertical surface.” The test involves loading the entirety of the energy in the test onto a concentrated section of the structure (

i.e.

, the corner of the roof). Thus, we believe that FMVSS No. 227 reflects an aspect of the “vertical surface” and other crash variations about which Advocates is concerned.

76

76

NHTSA also notes that, at this time, the petitioner's request to incorporate vertical surfaces to mimic a motorcoach accident scenario is impractical to meet. To adopt an objective, repeatable and meaningful test maneuver that incorporates highway speeds and vertical surfaces for the bus to impact, NHTSA should have additional information on what speed is representative, how to trip the bus to initiate a roll, what vertical surface objects are representative, etc. Such information is now unavailable. Further, a test incorporating highway speeds and vertical surfaces is currently not practical as the test conditions are exceedingly difficult to replicate, and pose inordinate safety risks to technicians conducting the test.

For the above reasons, NHTSA concludes that the ECE R.66-based test adopted in this final rule is an effective high-stringency test. The test substantially increases the likelihood that large buses will withstand the crash forces in a real-world rollover crash and provide a survival space to occupants.

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FMVSS No. 227 addresses motorcoach crashes that are more than quarter-turn crashes, without having to expose the vehicles to the exact same conditions. Given that all available information indicate that the FMVSS No. 227 test sufficiently replicates a deadly rollover crash, we are adopting the ECE R.66-based test in this final rule.

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Advocates also points to an NTSB Preliminary Report on a crash of a 1996 Setra Motorcoach operated by AM USA Express, Inc. Comparing the image of that bus (post-crash) in the NTSB Preliminary Report to a bus that NHTSA tested using ECE R.66 in research. Advocates argues that the ECE R.66 test fails to represent real-world crash conditions. Advocates does not present any information regarding the roof structures of these vehicles and whether their structures are similar enough to compare the severity of the crash conditions. There is insufficient information to make any reasonable conclusions comparing the crash severity in these two cases.

b. Intrusion Into the Survival Space

The NPRM proposed to prohibit intrusion into the “survival space,” demarcated in the vehicle interior from approximately the rear wall of the bus to 600 mm (24 inches) in front of the front surface of the seat back of the front row seats, by any part of the vehicle outside the survival space.

The purpose of the proposal is to guard against inadequate survival provided to occupants, especially belted ones, due to collapsing sidewalls, roof structure, or other objects. We intended the requirement to complement our standard requiring seat belts for passengers on the subject buses, to ensure that passengers retained in their seats will have a survival space protecting them from collapsing vehicle structure. Our research found structural intrusions into the survival space in the tested MY 1991, MY 1992, and MY 2000 buses. The NPRM proposed to define the vehicle survival space in a specific manner (see S4 of the proposed standard, 79 FR 46119-46120). The NPRM also proposed use of “survival space templates” in the compliance test.

Overall, commenters concurred with the survival space concept, suggesting small changes to the proposal.

MCI suggested that the survival space requirements should account for variations in vehicle floor heights so that the same height space can be provided in each vehicle segment. MCI requested survival space be defined relative to the forward and rear floor height of each segment of the vehicle.

NHTSA does not believe there is a need to change the survival space definition in response to MCI. The survival space definition already accounts for variations in interior compartment floor height front-to-rear and side-to-side in the vehicle.

However, the agency does believe it should clarify two ambiguities in the survival space definition. First, the “survival space” definition is clarified by defining “occupant compartment” to mean a space within the vehicle interior intended for driver and passenger use, excluding any space occupied by fixed appliances such as bars, kitchenettes, or toilets. Second, the definition of “survival space” is made clearer with regard to a forward-most seat that is not forward-facing. The specification of the centerline used to locate the reference point for the transverse vertical plane was not entirely clear in the NPRM. The “longitudinal” centerline should be

specified for the most forward point on the most forward seat. Further, the direction that the most forward seat faces will affect the relative positioning of the transverse vertical plane to this seat. This final rule therefore modifies the definition of survival space to specify that the front boundary of the survival space is a transverse vertical plane determined relative to the most forward seat

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in the passenger deck when the seat is in its forward-most position and its seat back is in the manufacturer's nominal design riding position. This transverse vertical plane is, (1) for a forward-facing seat, 600 mm in front of the most forward point on the longitudinal centerline of the front surface of the seat back, (2) for a rearward-facing seat, through the most forward point on the longitudinal centerline of the seat back, and (3) for a side-facing seat, through the most forward point on the seat, including the seat back, seat arm rest, and seat cushion.

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This seat could be a passenger seat, the driver's seat, or a temporary (jump) seat.

Intrusion of Items Into the Survival Space

MCI expresses concern that small glass shards falling from a window into the survival space may be a failure per the language of S5.1

79

of the NPRM.

79

79 FR 46120. The NPRM proposed the following regulatory text (S5.1): No part of the vehicle which is outside the survival space shall intrude into the survival space during the movement of the tilting platform or resulting from impact of the vehicle on the impact surface.

That was not NHTSA's intent in issuing this rule, but the agency agrees the proposed language could be read to produce such an outcome. NHTSA's intent in maintaining a survival space was to “set a minimum level of structural integrity for these buses, to help prevent dangerous structural intrusions into the occupant survival space.”

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The intent of the survival space requirement was to ensure “that the roof and sidewalls will be able to withstand the racking forces of a rollover crash.”

81

The purpose of retaining the window glazing to its mounting structure was to “ensure that the vehicle's structural integrity will prevent heavy glazing panels from falling into the passenger compartment and becoming ejection portals.”

82

We used “massive” and “heavy” to describe the window glazing panels and discussed a need to “[reduce] risk of injury from falling panels of glazing and occupant ejections.” As NHTSA's intent was not to require protection from “small glass shards” during the bus rollover, this final rule has clarified the requirements to reflect this view, as discussed below.

80

79 FR 46092, August 6, 2014.

81

Id.

82

Id.

NHTSA is providing in FMVSS No. 227 that objects of a minute size may intrude into the survival space. As to the size of the objects, the commenters do not provide a suggested definition for “small glass shards.” NHTSA thus turned to analyzing the Federal glazing standard to determine how the standard describes acceptably “small” glass shards regarding occupant safety. Glazing material used in motor vehicles must meet the requirements of FMVSS No. 205, “Glazing materials” (49 CFR 571.205). FMVSS No. 205 specifies that “[g]lazing materials for use in motor vehicles must conform to ANSI/SAE Z26.1-1996”

83

unless FMVSS No. 205 provides otherwise.

83

American National Standard for Safety Glazing Materials for Glazing Motor Vehicles and Motor Vehicle Equipment Operating on Land Highways-Safety Standard (ANSI/SAE Z26.1-1996).

ANSI/SAE Z26.1-1996 allows “small particles” to disengage from the glazing material during some of the laminated glazing

84

impact tests, though there is no express definition of “small particles” in ANSI/SAE Z26.1-1996. There is a 227 g (0.5 lb) 9.14 m (30 feet) ball drop impact test

85

in the ANSI standard for laminated glazing. The ball drop test allows “total separation of glass from the reinforcing or strengthening material” that does “not exceed 1935 square millimeters (mm

2

) (3 square inches (in

2

)) on either side.” (During the rollover testing the agency conducted in support of the FMVSS No. 227 NPRM, laminated glazing panels did shatter, but no discernable amount of the glazing material came free from the interlayer material.)

84

The requirements for the tempered glazing fracture test in the American National Standards Institute (ANSI) standard require that “no individual fragment free from cracks and obtained within 3 minutes subsequent to test shall weigh more than 4.25 gram (g) (0.15 ounce (oz)).”

85

ANSI/SAE Z26.1-1996, S5.12

The ANSI/SAE Z26.1-1996 maximum glazing separation size of 1935 mm

2

(3 in

2

) for laminated glazing evaluated using the ANSI ball drop test is helpful in indicating ANSI's determination of the maximum size of glazing that may enter the survival space without causing injury. Glazing pieces 1935 mm

2

(3 in

2

) or smaller are not massive or heavy, and the likelihood that they will cause serious blunt trauma injury is significantly lower compared to contact with an entire 84 kg (185 lb) glazing panel in a crash.

However, NHTSA further considered MCI's comment that “a failure of a single fastener (such as a rivet) that is part of the attachment of the parcel rack assembly could be deemed a failure of the test.” The agency decided that small items other than glazing pieces (

e.g.

, a bolt) should be allowed to enter the survival space if small glazing pieces are allowed. Given that the potential for injury caused by pieces entering the survival space is a function of the mass of the item, we decided to limit the items allowed to enter the survival space by the mass of the item.

As to what that mass should be, we again turned to ANSI/SAE Z26.1-1996 and glazing characteristics to start. The ANSI standard permits pieces of laminated glazing of 1935 mm

2

(3 in

2

) to separate (break off) in the 227 g (0.5 lb) 9.14 m ball drop impact test. We estimate that laminated glazing has a glass thickness of approximately 2.5 mm for each glass layer, and a glass density

86

of about 0.00251 g/mm

3

(1.445 ounce (oz)/in

3

). Thus, a piece of laminated glazing of 1935 mm

2

(3 in

2

) has a mass of approximately 12 grams (g) (0.43 oz). Factoring in a 3 g (0.11 oz) tolerance, we are prohibiting intrusion into the survival space by any part of the vehicle outside the survival space other than items with a mass of less than 15.0 grams (0.53 oz). Tempered glazing shatters into tiny pebbles that are significantly smaller and lighter than pieces of broken laminated glazing. The shattered pieces of tempered glazing would weigh significantly less than 15.0 grams (0.53 oz).

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Glass density value from

https://www.saflex.com/en/AutoReduceVehicleWeight.aspx

I couldn't access this 4/20/20.

C. Luggage Racks and Seat Anchorages

As discussed above in this preamble, the NPRM proposed to prohibit any anchorage of an interior overhead luggage rack or compartment or anchorage of a vehicle seat from completely separating from its mounting structure during the movement of the tilting platform or resulting from impact of the bus on the impact surface. After reviewing the comments, NHTSA has decided not to adopt the proposed requirements.

Under the NPRM, those proposed prohibitions would have applied even if the luggage rack does not enter the survival space, or the seat anchorages dislodged within the survival space. NHTSA has decided that the primary purpose of this rulemaking is to establish a roof strength and crush resistance standard that improves the resistance of roofs to deformation and intrusion,

i.e.

, by providing a survival

space to occupants in rollovers. The purpose is achieved by prohibiting

any

structure, such as overhead luggage racks, from intruding into the survival space. By prohibiting overhead luggage racks from impeding into the survival space in the rollover, overhead luggage racks will have to be better anchored to the bus wall than they had been in the past so that they do not detach and intrude into the survival space in the test. Thus, the proposed luggage rack provision is not needed to provide a survival space, since luggage racks are prohibited from intruding into the survival space. By being securely anchored so that they do not fall into the survival space, luggage racks will be less likely to impede egress in an emergency, or fall and cause head and neck injuries to occupants.

NHTSA has decided against adopting the NPRM's proposal that seat anchorages must not become dislodged during the test. The agency believes the seat anchorage provision is not necessary to achieve a survival space for occupants. NHTSA proposed the requirement for the retention of seat anchorages because of the agency's test of the MY 1991 Prevost LeMirage bus.

87

In the test, all seats on the opposite side of the impact detached from their sidewall mounting. A seat with a restrained mid-size adult male dummy completely separated from its anchorages and fell across the bus with the restrained dummy attached to the seat. NHTSA believed at the NPRM stage that the failure of the seat anchorages during the rollover test presented a significant safety risk to restrained occupants in bus rollover events and reduced the effectiveness of seat belts.

87

A summary of the test may be found in the NPRM, supra, in section IV.b 79 FR 46100-46102.

However, after considering the comments and other information, NHTSA concludes a requirement that the seat anchorages remain completely attached is unnecessary. In NHTSA's test of the MY 2000 MCI bus Model 102-EL3, all of the seats remained attached to their original anchorages. The seats were ballasted with either a 150 lb anthropomorphic ballast or with 150 lb steel weights, which is to say the seats remained attached even while tested under highly demanding conditions. This test of the MY 2000 MCI bus demonstrates that bus seat designs have improved since the MY 1991 and 1992 buses NHTSA tested in its test program.

Second, NHTSA believes the seat anchorage designs are likely to have improved even more since the design of the MY 2000 bus because of the agency's 2013 final rule requiring lap/shoulder belts on all large buses. The final rule requires the lap/shoulder belts to be integral to the bus seats, and that the belt anchorage, together with the seat anchorage, meet the rigorous strength requirements of FMVSS No. 210, “Seat belt assembly anchorages” 49 CFR 571.210. FMVSS No. 210 requires seat anchorages, attachment hardware, and attachment bolts to withstand loads of 13,345 N (3,000 lb) applied simultaneously to the lap belt portion and the shoulder belt portion of the Type 2 restraint system. Thus, the seat anchorages of new large buses meeting FMVSS No. 210 will be reinforced over and beyond the design of a MY 2000 bus, which reduces the likelihood even further that the seats will detach from the bus structure in a rollover as observed in the tests of the MY 1991 and 1992 buses. Thus, the proposed seat anchorage provision is not necessary to achieve a survival space for occupants.

d. Emergency Exits

The NPRM proposed that emergency exits must remain shut during the rollover test. The agency was concerned about emergency exits opening during a rollover, as NHTSA had observed this to happen in the tests conducted prior to the NPRM. The NPRM also proposed that roof and rear door emergency exits must be operable in the manner required under FMVSS No. 217, “Bus emergency exits and window retention and release,” after the test.

Comments Received

88

88

ABA requested an exclusion of entertainer buses from requirements in FMVSS No. 217, S5.2, “Provision of emergency exits.” The request is beyond the scope of the rulemaking and is not addressed in this preamble.

EvoBus commented that the proposal that roof exits remain closed is unnecessary, as it did not know that any passenger has been ejected through the roof exit. TEMSA requested that NHTSA move the requirement that side emergency exits remain closed to proposed FMVSS No. 217a. NTSB requested that side emergency exit doors also be required to meet FMVSS No. 227. Advocates suggested the requirement should apply to all side exits.

Agency Response

In response to EvoBus, NHTSA has observed roof exits opening in the FMVSS No. 227 tests conducted in support of the NPRM. Their opening posed an ejection safety risk that this final rule now addresses. Crash data do not identify the portals through which occupants were ejected, so data records” not indicating ejections through roof exits does not mean such ejections did not or will not occur. The final rule adopts a simple requirement that will reduce an ejection risk from open portals in the chaotic and unpredictable phases of a rollover. The cost of improved emergency latches is minor—$10 per coach for a total annual new bus fleet cost of $22,000. Congress, in enacting MAP-21, also wanted NHTSA to address the ejection risk from portals, and an opening in the bus roof caused by an open emergency exit poses an unreasonable risk of ejection of a child's head, limb or body, or those of an adult, in a rollover. NHTSA does not understand why design changes to the roof exits to enable them to meet the FMVSS No. 227 requirements would “cause opening failures,” nor did EvoBus explain its statement.

NHTSA does not agree with TEMSA that the requirements should be moved to FMVSS No. 217 or to the proposed FMVSS No. 217a. Both 217 and the proposed 217a do not address the dynamic torsional loads a bus structure transmits to the emergency exits during the rollover test in the manner FMVSS No. 227 does. Potential actuation of emergency exit latches due to inertial loading, assessed by FMVSS No. 227, is not assessed under current FMVSS No. 217 or proposed Standard No. 217a.

NTSB requests that FMVSS No. 227's requirements should also apply to side emergency exit doors.

89

NHTSA agrees, and had proposed that “emergency exits [should] remain latched to avoid becoming an ejection portal for unrestrained occupants,”

90

and that “all emergency exits shall not open during the rollover structural integrity test.”

91

The final rule adopts the proposal. However, NHTSA has decided not to require side emergency doors and emergency windows be operable after the crash test. The proposed provision that the exits must be operable after the test goes beyond purposes of the rulemaking (to provide a safe survival space and to reduce the risk of ejection through portals).

89

Under FMVSS No. 217, emergency exit “windows” and emergency exit “doors” are considered “emergency exits,” whereas an emergency exit door is a specialized type of emergency exit.

I.e.

, not all emergency exits are emergency exit “doors.”

90

79 FR 46109-46110.

91

79 FR 46110.

Further, there are challenges to requiring exits on the non-struck side to open with the bus on its side after the test.

92

FMVSS No. 217 specifies force

requirements needed to open the exit, calculated assuming the bus is upright on its wheels. FMVSS No. 217 only tests the subject buses when they are upright, so there are no gravity considerations. If the bus were tested on its side, the force requirement would have to be calculated to a yet-undetermined level to account for the mass of the window, the effect of gravity, and the fact that an occupant would be pushing on the exit while perched on seats they climbed on. NHTSA does not agree with Advocates that NHTSA should conduct an FMVSS No. 217 test after “righting” the bus on its wheels (buses are tested upright per FMVSS No. 217). The agency is concerned that righting the bus after the severe rollover test of FMVSS No. 227 may not be possible without further damaging the structural integrity of the bus. Further, conducting the test from inside the vehicle as per the FMVSS No. 217 test procedure would expose lab technicians to unreasonable safety risks.

92

This issue was discussed in the NPRM (79 FR 46110).

XI. Glazing Issues

a. Side Glazing on the Non-Struck Side of the Bus

The NPRM proposed that each side window glazing on the non-struck side of the vehicle would have to remain attached to its mounting such that there is no opening that will allow the passage of a 102 mm (4 inch) diameter sphere when a force of no more than 22 N is applied.

This final rule does not adopt this provision. The sphere test was proposed to ensure that, after the rollover test, the glazing remain securely attached to its mounting. Because the primary purpose of this rulemaking is to provide a necessary survival space to occupants in rollovers, the purpose is achieved by prohibiting harmful panes of glazing from intruding into the survival space. The proposed requirement that the glazing remain securely attached to its mounting is redundant to the survival space specification and unnecessarily complicates this rulemaking.

93

93

Some commenters objecting to the sphere test misunderstood the purpose of the test. The test was not intended to simulate an unbelted passenger's impact onto bus window glazing during a bus rollover. The sphere test was intended simply to measure whether the bus structure retained the glazing panels in the window frame when subjected to a rollover. In the final rule, this would be assessed by the prohibition that no large object enter the survival space. While retention of the glazing in its mounting could reduce occupant ejection, whether the glazing forms an opening through which an ejection could occur in a rollover crash, is the subject of NHTSA's proposed FMVSS No. 217a and will be addressed in the context of that rulemaking. 81 FR 27904, May 6, 2016,

supra.

b. Type of Glazing

EPGAA, Greyhound and Advocates requested that the agency require advanced glazing material in bus windows, while Prevost, Van Hool, and EvoBus suggest that tempered glass should be permitted. Prevost expresses that “there is a small possibility that some glazing could shatter when submitted to the proposed testing.” Prevost and EvoBus request an exclusion of tempered glazing from the rule, or that shattered glazing not be considered a failure of the FMVSS No. 227 requirements.

Agency Response

The agency is not distinguishing among glazing types in FMVSS No. 227 or providing exclusions of tempered glazing. The standard is generally performance-oriented and technology neutral, requiring window glazing and surrounding window frame structures on the non-struck sides of the bus to be manufactured so as not to unsafely intrude into the survival space in the rollover test. As discussed above, this final rule accommodates intrusion of small pebbles of tempered glass into the survival space. This final rule makes allowances for minute objects weighing less than 15.0 grams to enter the survival space, in recognition that it may be difficult, and unnecessary, to keep more miniscule pieces of glazing and other items from entering the survival space in the FMVSS No. 227 rollover event.

The requirement in FMVSS No. 227 preventing bus components from intruding into the survival space is critical to rollover safety if the subject buses employ advanced glazing that mitigate the risk of occupant ejection in rollovers. NHTSA's research

94

found that advanced glazing, such as laminated glazing, could pop out of its mounting due to torsional deformation of the structure around the window. FMVSS No. 227's survival space requirement would improve the structural integrity around window frames and prevent glazing from popping out or otherwise detaching from its window mount in a rollover.

94

Martec Limited, “Motorcoach Glazing Retention Test Development For Occupant Impact During a Rollover,” August 2006; Docket No. NHTSA-2002-11876-0015.

c. Moon Roofs

NTSB requested NHTSA consider including “moon roofs” in the glazing retention requirements of FMVSS No. 227. We agree with NTSB that “moon roofs” should be subject to the requirements of FMVSS No. 227, as there is a risk of passenger ejection through glass roofs during a bus rollover. Rather than use the term “moon roofs” however, hereinafter we use the term “roof panel/windows” since the latter term is more descriptive and inclusive of the components we seek to address.

Ejections through the roof occur in real-world crashes. From 2000-2009, two-thirds of the rollover fatalities in the subject buses were ejected occupants.

95

Two of the crashes (Turrell, Arkansas in 2004 and Mexican Hat, Utah in 2008) discussed in the NPRM involved roof separation from the bus. Almost all the passengers in those two crashes were ejected due to the loss of the bus roofs. In such crash events, unrestrained passengers can still be ejected if a bus that meets the survival space requirements fails to keep roof panels/windows closed or intact. We believe that manufacturers can use the same countermeasures to retain roof panels/windows to the glazing frames that they use to keep side window glazing attached to the side window frames.

95

79 FR 46098; August 6, 2014.

MAP-21

96

defines a portal as “any opening on the front, side, rear, or roof of a motorcoach that could, in the event of a crash involving the motorcoach, permit the partial or complete ejection of any occupant from the motorcoach, including a young child.” Roof panels/windows are portals per the MAP-21 definition. Any bus opening containing glazing material is a portal that can become an opening through which bus occupants may be partially or completely ejected if the glazing detaches from its mounting. The final rule's including roof panels/windows in FMVSS No. 227 accords with MAP-21. We will evaluate roof panels/windows like we do side windows.

I.e.

, no portion of a roof panel/window may enter the survival space, except for objects weighing less than 15.0 grams, and they must remain closed.

96

See Sec. 32072,

supra.

d. Struck-Side Window Evaluations

Several commenters (Advocates, Greyhound, NTSB, the families, and Ms. Stoos) request that the agency evaluate windows on the struck side as well as the non-struck side of the bus.

Under FMVSS No. 227, the agency can roll either side of the bus. Thus, manufacturers must ensure that vehicles can resist the torsional loads imparted into the structure on either side of the bus. To the extent the commenters suggest the sphere test should be conducted on the struck-side windows

when the bus is resting on the ground, as discussed above the agency is not adopting the sphere test, or any test involving lab technicians entering the rolled vehicle to assess compliance with a requirement.

XII. Test Procedure Issues

a. Ballasting the Vehicle

To simulate a real-world rollover incorporating foreseeable conditions that are challenging to the vehicle, NHTSA proposed to subject the vehicle to the forces resulting from the mass of restrained occupants. To achieve this, the NPRM proposed (in S6.2.5 of the regulatory text) that a mass up to 68 kg (150 lb) (ballast) be secured in each designated seating position (DSP) equipped with a seat belt.

97

The ballast would represent the mass of an “average” occupant, and is the mass NHTSA uses in determining a vehicle's GVWR per 49 CFR part 567, “Certification.” NHTSA stated that ballasting is important because it increases the weight and center of gravity of the vehicle, which better simulates the forces on the vehicle structure in a rollover when the seats are occupied by belted passengers. Also, when occupants are belted into the vehicle, their mass imparts crash forces to the seat anchorages during a crash, which NHTSA sought to replicate in the test (79 FR 46105-46107).

97

All DSPs in the buses are required to have seat belts per our November 25, 2013 MAP-21 final rule amending FMVSS No. 208 (78 FR 70416).

The agency indicated in the NPRM that it did not believe the method of ballasting or type of ballast used were of importance, as those factors will not significantly alter the forces imposed on the vehicle structure or the seat anchorages during compliance testing, so long as the ballast is 68 kg (150 lb) at each DSP. NHTSA noted in the NPRM that the NPRM differed from ECE R.66 on this issue of ballasting. ECE R.66 specifies the option of two different methods of securing occupant ballast to the passenger seats.

98

It reduces the load to 34 kg (75 lb) when a fixed ballast is used (79 FR 46106). Further, it specifies a different ballasting method.

99

98

As discussed in the NPRM (79 FR 46107), we tested both types of ballasts, anthropomorphic (“water dummies”) ballasts and fixed steel ballasts, to determine the feasibility of each and the differences between the two. We found that the method of ballasting and type of ballast used were not important, as these factors did not significantly alter the forces upon the vehicle structure or the seat anchorages during the test, so long as the ballast is 68 kg (150 lb). Four commercially available “water dummies,” each filled with 68 kg (150 lb) of sand, were installed in one full row of seats (four seating positions) and were secured with ratchet straps that were configured to simulate Type 2 seat belts. Steel ballasts, 68 kg (150 lb) per seating position, were installed in a second full row of seats (four seats). In this row, steel plates were placed on top of each seat cushion and were secured with bolts that passed through the cushion and attached to a bar which clamped onto the seat frame. The overall center of gravity of the bus, and consequently, the energy absorbed in the test, was only slightly higher (less than 3 percent) when the water dummies were used compared to when the fixed weights were used. The differences in forces and moments generated at the anchorages due to the ballasts were also small.

99

In addition to specifying a different weight for fixed steel plate ballasts, ECE R.66 requires the ballasts be fixed to the seat such that its center of gravity aligns with that of the anthropomorphic ballast (

i.e.

, approximately 100 mm forward and 100 mm above the seating reference point). However, NHTSA simply proposed to fix the steel ballasts to the seat because in the agency's research NHTSA found it difficult to position and fix the rigid weights per the ECE specification. We investigated whether affixing the rigid weights as specified by ECE R.66 is necessary and stated in the NPRM that it was not. The different center of gravity heights between the anthropomorphic ballasts and the fixed weight ballasts did not appear to affect the overall performance of the vehicle in the rollover test. 79 FR 46107.

Comments Received

Several bus manufacturers commented on the proposal, all requesting that we adopt the ballasting approach of ECE R.66 (

i.e.

, the anthropomorphic ballast at 68 kg (150 lb) and the fixed steel plate ballast at 34 kg (75 lb)).

100

All the commenters essentially argue that passengers in a bus, restrained by the seat belts, will not transfer their entire load onto the seat anchorages and bus structure in the same way as fixed ballasts. Therefore, commenters argue, when using the fixed steel plate ballasts, the ballast weight should be 34 kg (75 lb) (

i.e.

, 50 percent of the weight for anthropomorphic ballasts).

100

Greyhound Lines, Inc., an operator, suggested that NHTSA should ballast the overhead luggage racks during rollover testing. Ballasting of luggage rack and the lower luggage compartment of a motorcoach was not proposed in the August 6, 2014 NPRM and therefore the public was not provided a full opportunity to comment on this issue. ECE R.66 does not require ballasting of the luggage rack, and NHTSA does not see a safety need for a requirement to ballast the luggage racks.

In support of their view that a 50 percent weight is appropriate for fixed ballasts, the commenters argue that ECE R.66 considers a 75-lb weight for fixed steel ballasts equivalent to the 150-lb anthropomorphic ballast secured with the seat belt. Van Hool cites an ECE Ad Hoc Expert Group document that puts the load transferred by belted occupants to the vehicle structure as between 0 and 100 percent of the standard passenger mass of 68 kg (150 lb).

101

Prevost and Daimler both cite an ECE analysis finding that 50 percent of the restrained occupant's weight transfers to the bus structure during a crash.

102

101

See

Report about the Ad-Hoc Expert Group (AHEG) meeting dealing with the development of Regulation 66 (Frankfurt, 22-23, November, 2001),

available at https://www.unece.org/fileadmin/DAM/trans/doc/2002/wp29grsg/TRANS-WP29-GRSG-82-inf02.doc

(last accessed February 8, 2017).

102

Study about the Incidence of the Use of Safety Belts with regard to Regulation 66 of Geneva, presented by Spain at the 81th Working Party on General Safety Provisions (GRSG), October, 2001,

https://www.unece.org/fileadmin/DAM/trans/main/wp29/wp29wgs/wp29grsg/grsginf/81/grsg81_inf09.doc

(last accessed February 8, 2017).

Agency Response

NHTSA is adopting the provision to use the 68 kg (150 lb) ballast in NHTSA's compliance test. NHTSA does not concur that a 75-lb (50 percent lighter weight) fixed ballast would simulate a similar amount of force on the seat anchorages and bus structure as a 150-lb occupant.

Prevost's and Daimler's comments reflect the state of knowledge in 2001, a time early in the development of ECE R.66. According to their cited analysis, there were no experimental data available at the time to evaluate the percentage of mass that should be included in the test. At that time, it was then theorized that 50 percent of the occupant weight was an appropriate estimate for the weight that a restrained occupant would transfer to the bus structure. However, subsequent published studies have found that the 50 percent value grossly underestimates the amount of force imparted by restrained bus occupants.

As discussed in the NPRM (79 FR 46106), an Australian study that utilized bus section testing and computer simulations

103

estimated that 93 percent of a lap/shoulder belt-restrained occupant mass, 75 percent of a lap belt-restrained occupant mass, and 18 percent of an unrestrained occupant mass are effectively coupled to the vehicle structure during a rollover. Further, a European Commission sponsored study in 2003

104

found that the percentage of occupant mass coupled to the vehicle structure during a rollover is 90 percent for lap/shoulder belted occupants and 70 percent for lap belted occupa

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