Federal Motor Vehicle Safety Standards; Fuel System Integrity of Compressed Natural Gas Vehicles Over 4536 Kilograms Gross Vehicle Weight Rating

DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR 571

[Docket No. 94-31; Notice 01]

RIN 2127-AF29

Federal Motor Vehicle Safety Standards; Fuel System Integrity of

Compressed Natural Gas Vehicles Over 4536 Kilograms Gross Vehicle

Weight Rating

AGENCY: National Highway Traffic Safety Administration (NHTSA),

Department of Transportation (DOT).

ACTION: Request for comments.

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SUMMARY: The purpose of this notice is to assess the need to regulate

the fuel system integrity of vehicles with a gross vehicle weight

rating (GVWR) of greater than 4536 kilograms that are fueled with

compressed natural gas (CNG). Comments are requested regarding the need

for fuel system integrity standards for CNG-powered vehicles with a

GVWR of greater than 4536 kilograms, including transit buses, intercity

buses, trucks, and other heavy vehicles.

DATES: Comments must be received by July 5, 1994.

ADDRESSES: Comments should refer to the docket and notice numbers set

forth above and be submitted to the Docket Section, NHTSA, room 5109,

400 Seventh Street SW., Washington, DC 20590 (Docket hours are from

9:30 a.m. to 4 p.m., Monday through Friday).

FOR FURTHER INFORMATION CONTACT: Mr. Gary Woodford, General Engineer,

Special Projects Staff, Office of Rulemaking, National Highway Traffic

Safety Administration, 400 Seventh Street SW., Washington, DC 20590.

Telephone: (202) 366-4931.

SUPPLEMENTARY INFORMATION: The National Highway Traffic Safety

Administration (NHTSA) anticipates a significant increase in the number

of alternatively fueled motor vehicles in the United States. This

expectation stems from initiatives by the President, Congress, State

and local governments, and private interest, since these vehicles will

help reduce air pollution and conserve petroleum fuel. NHTSA has

undertaken a comprehensive program to address the safe performance of

these vehicles on the road and in crashes. Further, because the Clean

Air Act specifies that vehicle fleets in non-attainment areas (mostly

large cities) must be converted to clean burning fuels, many city

transit bus fleets are being converted to run on fuels such as

compressed natural gas (CNG). As NHTSA has become more aware of these

fleets of heavy vehicles powered by CNG, the agency believes that their

safe performance merits examination.

On January 21, 1993, NHTSA published a notice of proposed

rulemaking (NPRM) which proposed requirements for CNG fuel system and

fuel container integrity (58 FR 5323). The vehicle fuel system

requirements were proposed to apply to vehicles with a GVWR of 4536

kilograms or less, and all school buses. The container requirements

were proposed to apply to CNG fuel containers for any vehicle.

On April 25, 1994, the agency published a final rule (59 FR 19648),

which addresses the fuel system integrity of CNG vehicles. The new

regulation, Federal Motor Vehicle Safety Standard (FMVSS) No. 303,

applies to all passenger cars, trucks, buses, and multipurpose

passenger vehicles with a GVWR of 4536 kilograms of less, and all

school buses regardless of weight. FMVSS No. 303 sets allowable leakage

limits for the vehicle fuel system after a barrier crash test. With

regard to the fuel container requirements, NHTSA anticipates issuing

another final rule that will specify performance requirements

addressing the strength, durability, and pressure relief of CNG fuel

containers. In addition, as a result of public comments on the January

1993 NPRM, the agency anticipates issuing a supplemental notice of

proposed rulemaking for CNG fuel containers addressing internal

corrosion, brittle fracture under low temperatures, environmental

degradation, external damage, and fragmentation.

The January 1993 NPRM briefly discussed the issue of whether

vehicles with a GVWR of over 4536 kilograms, other than school buses,

should be included in the vehicle requirements. The agency believes

that an opportunity should be provided for a more focused view on this

issue. This request for comment will serve that purpose.

A total of 58 comments were received on the NPRM, of which six

addressed CNG safety for vehicles over 4536 kilograms GVWR other than

school buses. Four of the six commenters, Navistar, Chrysler, Flexible,

and Amoco, believed that federal safety requirements should not apply

to CNG-powered heavy vehicles. The main reason given by the commenters

was that the vehicle applicability of the CNG fuel system integrity

standard should be the same as that for NHTSA's liquid fuel system

integrity standard, FMVSS No. 301, ``Fuel System Integrity.'' The

latter only applies to vehicles with a GVWR of 4536 kilograms or less,

and school buses. However, two commenters believed that the

requirements should apply to heavier vehicles. The Transportation

Manufacturing Company, a bus manufacturer, believed that heavy vehicles

should have requirements that are comparable to those for smaller

vehicles. No rationale was provided. The Washington Superintendent for

Public Instruction (WSPI), also believed that these vehicles should be

regulated. WSPI stated that the agency should consider including these

vehicles in the proposed rule, but did not offer a rationale.

Because of the lack of accident data indicating a fuel system

integrity problem for CNG-powered heavy vehicles, and the lack of

rationale from the two supporters, the agency concluded that FMVSS No.

303 should not apply to heavy vehicles. However, because of the

increasing number of CNG-powered transit buses, the agency seeks

information by which to consider whether federal safety action is

desirable, for both transit buses and or other heavy vehicles. It may

be that action is merited with regard to buses, which carry many

occupants and can have high traffic exposure, but not other heavy

vehicles with only one or two occupants.

Current and Proposed Regulations

As part of NHTSA's inquiry in this notice, the agency seeks

comments on the desirability of actions which would be harmonized with

those of Canada.

United States Requirements

FMVSS No. 303 requires that school buses, regardless of weight,

must comply with a moving contoured barrier crash test. In this test, a

barrier traveling longitudinally at 48 kilometers per hour impacts the

bus at any point and angle. During and after the impact, the fuel

pressure drop must not exceed a specified limit. The final rule

contains no requirements for heavy vehicles other than school buses

with a GVWR of over 4536 kilograms.

Canada's Existing and Proposed Requirements

Currently, Canadian motor vehicle safety standard No. 301.2, ``CNG

Fuel System Integrity,'' requires that all vehicles with a GVWR of more

than 4536 kilograms be subjected to a 48 kilometers per hour contoured

barrier crash test. This is similar to the test NHTSA requires for

school buses in FMVSS No. 303. On December 11, 1993, Canada proposed an

amendment to its standard. Under the amendment, the current requirement

would apply to vehicles with containers mounted lower than 183

centimeters from the ground. If the fuel containers are mounted 183

centimeters or more above the ground, the vehicle would need to meet

the requirements of the National Standard of Canada CAN/CGA-B149.4-M91

Natural Gas for Vehicles Installation Code, dated January 1991 (copy

available in the docket). This is a design standard which specifies in

great detail the method for building a CNG vehicle.

Request for Comments

NHTSA seeks two types of information in this notice. First, the

agency seeks information regarding the current and projected population

size and vehicle type (transit bus, intercity bus, heavy truck, or

other heavy vehicle) for CNG vehicles with a GVWR of over 4536

kilograms. Second, NHTSA seeks information about the potential safety

problems of these vehicles. When appropriate, please comment by vehicle

type, i.e., transit bus, intercity bus, heavy truck, or other type of

heavy vehicle.

CNG Heavy Vehicle Population: Current and Projected

1. The agency requests information on how many CNG transit buses,

intercity buses, heavy trucks, and other heavy vehicles of over 4536

kilograms GVWR are in service or are planned to be placed in service in

the United States. How many of these vehicles are made by an original

equipment manufacturer (OEM) and how many are aftermarket vehicles that

are converted from a vehicle powered by gasoline, diesel, or other

fuel?

2. How many entities manufacture heavy CNG vehicles by type, i.e.,

transit bus, intercity bus, heavy truck, or other type of heavy

vehicle? How many convert them from other fuels, by type, if

appropriate? What specifications are used for converting these

vehicles? Do voluntary industry guidelines exist? Please describe and

provide the guidelines or citations.

3. How long have heavy CNG vehicles (by type) been used in this

country? What are the projections for their future use, in terms of

numbers and in type of usage?

4. What are the various locations for mounting CNG containers on

heavy vehicles? Which are more common; less common? Why? At what height

are the CNG containers mounted? Are they typically protected by

shielding or cages? What factors go into deciding where to mount the

container on the vehicle? How many CNG containers are typically placed

on a heavy vehicle, and how much do the containers weigh? Does the

number of containers vary, depending upon the type of vehicle, i.e.,

transit bus, intercity bus, heavy truck, or other type of heavy

vehicle?

CNG Heavy Vehicle Safety Problems

The agency foresees four potential areas for examination with

regard to these vehicles:

--Performance in Crashes

--Venting

--Leakage Detection

--Refueling

Performance in Crashes

The agency is interested in obtaining specific information about

crashes involving these heavy vehicles. General information about the

number of accidents as well as information regarding specific issues

such as container detachment would be helpful.

5. Have there been any CNG fuel container or fuel system failures

in these types of vehicles? If so, describe the failure, e.g., sequence

of events, what failed, and how it failed. If the failure occurred as

the result of a crash, was another vehicle involved? Please describe

the other vehicle.

6. Was the vehicle a transit bus, intercity bus, heavy truck, or

some other type of heavy vehicle? Was it an OEM vehicle or a

conversion? Who was the manufacturer of the vehicle? If it was a

conversion, who did the conversion? Was the conversion done before or

after the vehicle's first consumer purchase?

7. Please identify and describe any situations where a container

became detached in a crash situation? Did the container leak? If

crashes occurred, were they reported to a policy agency, hazardous

materials agency, or other State/local agency?

8. Should the agency specify how the fuel containers should be

attached to the vehicles? Should a requirements apply to all vehicles

or just for those with containers mounted greater than 183 centimeters

above the ground (such as referenced in the Canadian proposal)? Are CNG

tanks rigidly mounted or are they mounted so as to be isolated from

shock in a crash, permitting some allowable design movement? What is

the typical orientation of the CNG tank with respect to the

longitudinal axis of the vehicle? Does a CNG tank's mounting

orientation and method affect its useful life?

9. Were there any injuries to the vehicle occupants, pedestrians,

emergency personnel, or other individuals? What was the type and

seriousness of the injury?

10. What type (steel, aluminum, fiberglass wrap, carbon fiber wrap,

hoop wrap, full wrap, all composite, or other) was the fuel container?

What were the dimensions of the container? What was the service

pressure of the container? Who manufactured the container? How long had

it been in service? To which design specification or standard were the

tanks built?

11. Should any Federal standard include a labeling requirement to

address the periodic reinspection of fuel systems on alternatively

fueled vehicles? Should States establish guidelines to address the

periodic reinspection or recertification of such fuel systems? Should

these schedules be set at specified time or mileage intervals? After a

vehicle is involved in an accident?

12. Should CNG heavy vehicles, which are not school buses, be crash

tested for fuel system integrity in the same way as heavy school buses

under FMVSS No. 303, i.e., a contoured barrier traveling at 48

kilometers per hour striking the test vehicle at any point and angle?

If so, which types of CNG heavy vehicle should be included, i.e.,

transit bus, intercity bus, heavy truck, or other type? Are there other

tests or guidelines which would be more appropriate to assure the fuel

system integrity of such vehicles? If so, what are they?

Venting

Because of the size of these vehicles, there may be large enclosed

areas in which natural gas could accumulate if there is a slow leak in

the CNG fuel system.

13. Are there instances where gas accumulated? Did any of them

result in explosions?

14. Should venting of the container away from possible areas of

accumulation and potential ignition sources be required to address

leakage accumulation?

15. What experimental or observed data are available regarding the

dispersion behavior that results from a CNG fuel system leak? Will the

gas rise or remain near the ground? If the gas remains near the ground,

how long will it remain there?

Leakage Detection and Warning

If there is a leak in the fuel system, there would be little or no

visible evidence of the gas accumulation. If persons nearby could not

smell the gas, it could accumulate in an area near them without notice,

which would increase the potential for an explosion.

16. Are there instances where CNG leaked out of a vehicle fuel

system and caused a safety problem before the natural gas was detected?

Describe how the situation occurred.

17. Should a leakage detection/warning system be required in

vehicles with a GVWR of over 4536 kilograms to detect leakage of CNG as

well as to warn persons nearby of the potential hazard? What type of

system? Is it commercially available? What would be the cost? Would the

leakage detection/warning system, including its power source, become a

potential ignition sources when activated?

Refueling

NHTSA seeks information on potential safety hazards associated with

the refueling of heavy CNG vehicles.

18. Are manufacturers or fleet operators aware of safety hazards or

accidents that have occurred during refueling operations? If so, please

provide information on them.

19. What items are included in current guidelines or procedures for

CNG refueling, such as the need for grounding straps, operator

protective clothing, etc.?

20. Is a small amount of CNG normally released during connecting/

disconnecting of the refueling equipment? If so, how much? Are devices,

such as excess flow valves, used in refueling equipment to prevent

excess CNG leakage in the event of a refueling line rupture? To what

extent are such devices used?

21. What standards or guidelines currently exist for refueling

couplers and related equipment?

Submission of Comments

The agency invites written comments from all interested parties. It

is requested that 10 copies of each written comment be submitted.

No comment may exceed 15 pages in length. (49 CFR 553.21).

Necessary attachments may be appended to a comment without regard to

the 15-page limit. This limitation is intended to encourage commenters

to detail their primary arguments in a concise fashion.

If a commenter wishes to submit specified information under a claim

of confidentiality, three copies of the complete submission, including

purportedly confidential business information, should be submitted to

the Chief Counsel, NHTSA, at the street address given above and seven

copies from which the purportedly confidential information has been

deleted should be submitted to the Docket Section. A request for

confidentiality should be accompanied by a cover letter setting forth

the information specified in the agency's confidential business

information regulation, 49 CFR part 512.

All comments received before the close of business on the comment

closing date indicated above will be considered, and will be available

for examination in the docket at the above address both before and

after the closing date.

To the extent possible, comments filed after the closing date will

also be considered. NHTSA will continue to file relevant information as

it becomes available in the docket after the closing date, and it is

recommended that interested persons continue to examine the docket for

new material.

Those persons desiring to be notified upon receipt of their

comments in the rules docket should enclose a self-addressed, stamped

postcard in the envelope with their comments. Upon receiving the

comments, the docket supervisor will return the postcard by mail.

Authority: 15 U.S.C. 1392, 1401, 1403, 1407, 1417; delegations

of authority at 49 CFR 1.50 and 49 CFR 501.8.

Issued on May 2, 1994.

Barry Felrice,

Associate Administrator for Rulemaking.

[FR Doc. 94-10897 Filed 5-5-94; 8:45 am]

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