Pasar al contenido principal

NHTSA Interpretation File Search

Overview

NHTSA's Chief Counsel interprets the statutes that the agency administers and the standards and regulations that it issues. Members of the public may submit requests for interpretation, and the Chief Counsel will respond with a letter of interpretation. These interpretation letters look at the particular facts presented in the question and explain the agency’s opinion on how the law applies given those facts. These letters of interpretation are guidance documents. They do not have the force and effect of law and are not meant to bind the public in any way. They are intended only to provide information to the public regarding existing requirements under the law or agency policies. 

Understanding NHTSA’s Online Interpretation Files

NHTSA makes its letters of interpretation available to the public on this webpage. 

An interpretation letter represents the opinion of the Chief Counsel based on the facts of individual cases at the time the letter was written. While these letters may be helpful in determining how the agency might answer a question that another person has if that question is similar to a previously considered question, do not assume that a prior interpretation will necessarily apply to your situation.

  • Your facts may be sufficiently different from those presented in prior interpretations, such that the agency's answer to you might be different from the answer in the prior interpretation letter;
  • Your situation may be completely new to the agency and not addressed in an existing interpretation letter;
  • The agency's safety standards or regulations may have changed since the prior interpretation letter was written so that the agency's prior interpretation no longer applies; or
  • Some combination of the above, or other, factors.

Searching NHTSA’s Online Interpretation Files

Before beginning a search, it’s important to understand how this online search works. Below we provide some examples of searches you can run. In some cases, the search results may include words similar to what you searched because it utilizes a fuzzy search algorithm.

Single word search

 Example: car
 Result: Any document containing that word.

Multiple word search

 Example: car seat requirements
 Result: Any document containing any of these words.

Connector word search

 Example: car AND seat AND requirements
 Result: Any document containing all of these words.

 Note: Search operators such as AND or OR must be in all capital letters.

Phrase in double quotes

 Example: "headlamp function"
 Result: Any document with that phrase.

Conjunctive search

Example: functionally AND minima
Result: Any document with both of those words.

Wildcard

Example: headl*
Result: Any document with a word beginning with those letters (e.g., headlamp, headlight, headlamps).

Example: no*compl*
Result: Any document beginning with the letters “no” followed by the letters “compl” (e.g., noncompliance, non-complying).

Not

Example: headlamp NOT crash
Result: Any document containing the word “headlamp” and not the word “crash.”

Complex searches

You can combine search operators to write more targeted searches.

Note: The database does not currently support phrase searches with wildcards (e.g., “make* inoperative”). 

Example: Headl* AND (supplement* OR auxiliary OR impair*)
Result: Any document containing words that are variants of “headlamp” (headlamp, headlights, etc.) and also containing a variant of “supplement” (supplement, supplemental, etc.) or “impair” (impair, impairment, etc.) or the word “auxiliary.”

Search Tool

NHTSA's Interpretation Files Search



Displaying 3401 - 3410 of 16513
Interpretations Date
 search results table

ID: aiam2548

Open
Mr. D. Bruce Henderson, Legislative Engineer, NVT Motorcycles, Ltd., Lynn Lane, Shenstone, Lichfield Staffordshire WS14 OEA, England; Mr. D. Bruce Henderson
Legislative Engineer
NVT Motorcycles
Ltd.
Lynn Lane
Shenstone
Lichfield Staffordshire WS14 OEA
England;

Dear Mr. Henderson: This is in reply to your letter of March 23, 1977, asking for a interpretation of Federal Motor Vehicles Safety Standard No. 123, *Motorcycle Controls and Displays*.; You have noted that Table 3 required the headlamp upper beam indicato to be identified as 'High Beam' while its control may be marked 'Hi' and 'Lo' at the appropriate positions. Because of space limitations near the upper beam indicator you would like to use the identification 'Hi Beam.'; In our opinion 'Hi Beam' would meet the intent of Standard No. 123 t provide a clearly recognizable identification for the upper beam indicator since, as you noted, it would make the display read the same as the control.; Sincerely, Frank A. Berndt, Acting Chief Counsel

ID: aiam4865

Open
Mr. Richard F. Land Bureau of Manpower and Facilities Tennessee Department of Health and Environment 287 Plus Park Blvd. Nashville, TN 37247-0701; Mr. Richard F. Land Bureau of Manpower and Facilities Tennessee Department of Health and Environment 287 Plus Park Blvd. Nashville
TN 37247-0701;

"Dear Mr. Land: This responds to your February 12, 1991 letter to Ms Fujita of my staff concerning the ambulance fleet you recently inspected. Each ambulance had a wooden block mounted under the accelerator pedal to limit the driver's ability to accelerate the vehicle. You state that Tennessee law does not prohibit installation of these 'makeshift speed governors.' However, you would like to know whether NHTSA's requirements would prohibit installation of the blocks. The answer to your question is no. In a March 26 telephone conversation with Ms. Fujita, you said that the blocks were installed by the ambulance owner. Our standards do not regulate in any manner how a vehicle owner can modify his or her vehicle. If the blocks were installed by a motor vehicle manufacturer, distributor, dealer or repair business, certain requirements of the Vehicle Safety Act (copy enclosed) would apply. Section 108(a)(2)(A) of the Act prohibits any person in the aforementioned categories from knowingly 'render ing inoperative' any equipment or element of design installed in compliance with an FMVSS. However, there would be no rendering inoperative of compliance with the FMVSS for accelerator control systems (FMVSS 124) in the situation you described, because that FMVSS does not establish requirements for accelerator pedal actuation. Of course, the installation of the block must not have rendered inoperative compliant equipment or designs on the vehicle that were installed pursuant to other safety standards. For example, the block must not interfere with the vehicle's braking ability. I hope this information is helpful. Please contact us if you have further questions. Sincerely, Paul Jackson Rice Chief Counsel Enclosure";

ID: aiam5262

Open
Mr. Donald E. Schmitz Engineering Manager Featherlite Mfg., Inc. P.O. Box 380 Cresco, IA 52136; Mr. Donald E. Schmitz Engineering Manager Featherlite Mfg.
Inc. P.O. Box 380 Cresco
IA 52136;

Dear Mr. Schmitz: This responds to your letter of October 7, 1993, t Acting Administrator Smolkin which 'addresses the TTMA, September 8, 1993, Recommended Practice on Trailer Conspicuity Systems.' You inform us that you 'will begin applying the conspicuity tape to the trailer's bottom as shown' in the TTMA sketches, and 'will assume our interpretation is correct . . . unless we receive a response from your office within ten days.' If you wish an interpretation of the TTMA drawings, you should consult that organization. This agency provides interpretations of Federal Motor Vehicle Safety Standard No. 108, Lamps, Reflective Devices, and Associated Equipment. With respect to paragraph S5.7, which establishes conspicuity system requirements for large trailers, effective December 1, 1993, the agency published an amendment on October 6, the day before your letter, which modified the mounting height requirements adopted in December 1992. The original requirement of 'as close as practicable to 1.25 m above the road surface' has been changed to a range that is 'as close as practicable to not less than 375 mm and not more than 1525 mm above the road surface. . . .' I enclose a copy of the amendment for your information. See paragraph S5.7.1.4.2(a) for the change. Sincerely, John Womack Acting Chief Counsel Enclosure;

ID: aiam0060

Open
Mr. Ernest Cipriano, President, Weslock Company, 13344 South Main Street, P.O. Box 54369, Los Angeles, CA 90054; Mr. Ernest Cipriano
President
Weslock Company
13344 South Main Street
P.O. Box 54369
Los Angeles
CA 90054;

Dear Mr. Cipriano: Your letter of April 22, 1968, to Mr. Bridwell has been referred to m for reply.; You state that it is your understanding that the proposed rule makin in Docket 2-16 will require door locks on trailers and mobile homes to be so constructed 'as to be recessed flush on exterior doors.' Federal motor vehicle safety standard No. 206, Door Latches, Hinges, and Locks - Passenger Cars, was originally issued on January 31, 1967 and became effective on January 1, 1968. An amendment to this standard was issued on April 24, 1968 with an effective date of January 1, 1969.; Neither the standard as presently written or the proposed amendment i Docket 2-16 is applicable to trailers and mobile homes. Moreover, there is no provision either in the standard or in the proposed amendment which requires that door locks must be so constructed 'as to be recessed flush on exterior doors,' even as to those motor vehicles to which the standard applies presently or to which it is proposed to apply in Docket 2-16. For your information, we are enclosing a copy of the recent amendment to Standard No. 206 as attachment No. 1, and a copy of the proposed amendment for Docket 2-16 as attachment No. 2.; In view of the foregoing, you may wish to reconsider your request tha we forward to you the comments contained in Docket 2-16. The cost to you for forwarding those comments would be fifty cents a page and the number of pages contained in Docket 2- 16 is considerable. Since your understanding of the thrust of Docket 2-16 is not correct, your request for an extension of time to May 25, 1968 is denied.; Sincerely, Robert M. O'Mahoney, Assistant Chief Counsel

ID: aiam5632

Open
Mr. Larry W. Strawhorn Vice President of Engineering American Trucking Associations 2200 Mill Road Alexandria, VA 22314-4677; Mr. Larry W. Strawhorn Vice President of Engineering American Trucking Associations 2200 Mill Road Alexandria
VA 22314-4677;

"Dear Mr. Strawhorn: This letter responds to your request for a interpretation of the antilock malfunction indicator requirements set forth at S5.2.3.3 of Standard No. 121, Air Brake Systems. This provision explains the situations in which the trailer lamp malfunction indicator must remain activated. Section S5.2.3.3 reads as follows: S5.2.3.3 Antilock Malfunction Indicator. Each trailer (including a trailer converter dolly) manufactured on or after March 1, 1998 and before March 1, 2006 shall be equipped with a lamp indicating a malfunction of a trailer's antilock brake system. Such a lamp shall remain activated as long as the malfunction exists whenever the power is supplied to the antilock brake system. The display shall be visible within the driver's forward field of view through the rearview mirror(s), and shall be visible once the malfunction is present and power is provided to the system. (Emphasis added.). In particular, you request that the agency confirm your belief that the lamp activation pattern for trailers may be such that the bulb be ON when the antilock system is working properly and OFF when a malfunction exists, the antilock system is not getting electrical power, or the lamp bulb is burnt out. You contended that such an activation pattern provides a fail safe pattern i.e., it will signal an inoperative antilock system even when the system is not receiving electrical power or the lamp bulb is burnt out. NHTSA disagrees with your suggested reading of the malfunction indicator requirements. Such a reading would be inconsistent with S5.2.3.3's language stating that the lamp must 'remain activated as long as the malfunction exists whenever the power is supplied to the antilock brake system.' As with other malfunction indicators, the agency intends the malfunction indicator to activate when a malfunction exists and not activate when the system is functioning properly. To require otherwise would be inconsistent with our requirements for other indicators and thus would create confusion. Please note that NHTSA provided a lengthy discussion about the issue of a malfunction indicator's activation protocol in the March 10, 1995 final rule. (60 FR 13216, 13246) The agency stated that in response to an ABS malfunction, a trailer or tractor indicator must activate and provide a continuous yellow signal. The agency explained that such a common indicator pattern standardizes the activation format, thus reducing ambiguity and confusion and expediting Federal and State inspections. I hope this information has been helpful. If you have any other questions, please contact Marvin Shaw of my staff at this address or by phone at (202) 366-2992. Sincerely, John Womack Acting Chief Counsel";

ID: aiam4920

Open
Mr. Robert W. Smith President Auto Safety Corporation Box 424 Middletown, Delaware 19709; Mr. Robert W. Smith President Auto Safety Corporation Box 424 Middletown
Delaware 19709;

Dear Mr. Smith: This responds to your letter of October 14, 1991, t Taylor Vinson of this Office, asking for a confirmation of your interpretation of Motor Vehicle Safety Standard No. 108, based upon a meeting with Mr. Vinson on August 15, l990. You are developing a license plate frame that incorporates a 'flashing/steady burning stop lamp', for use on passenger cars and motorcycles, and 'an auxiliary flashing/steady burning stop lamp' for use on vans, minivans, and pickup trucks. You cite a letter of this agency to Bettie Lou Simcox, dated October 24, 1986, as authority for your understanding that Standard No. 108 allows the use of a flashing, steady burning stop lamp. Standard No. 108 covers original motor vehicle lighting equipment, and lighting equipment that is intended to replace the original lighting equipment. It does not cover supplementary or novelty lighting equipment offered in the aftermarket. Mrs. Simcox asked us about the acceptability of an aftermarket stop lamp which, when the brake is applied, pulses before going into a steady burning mode. We informed Mrs. Simcox that her lamp was unacceptable as replacement equipment because Standard No. 108 requires original equipment stop lamps, and lamps designed to replace that equipment, to be steady burning in use, but that it would be permissible under Standard No. 108 as a supplementary stop lamp. For the same reason, your invention would not be prohibited by Standard No. 108 if it is offered in the aftermarket as a supplementary stop lamp, which we understand is your intent. You should be aware that Standard No. 108 specifically requires motor vehicles to be equipped with one or more license plate lamps. We are uncertain of the effect, if any, that the installation of your combination license plate frame/supplementary stop lamp would have upon conformance of a vehicle's license plate lamp(s) with the requirements of Standard No. 108. We therefore remind you of the prohibition in the National Traffic and Motor Vehicle Safety Act that a manufacturer, distributor, dealer or motor vehicle repair business may not render inoperative, in whole or in part, a device such as the license plate lamp that has been installed in accordance with a safety standard such as Standard No. 108. Sincerely, Paul Jackson Rice Chief Counsel;

ID: aiam0430

Open
Mr. Rolf Burke, Vice-President, Market Tire Company, 5481 Randolph Road, Rockville, MD 20852; Mr. Rolf Burke
Vice-President
Market Tire Company
5481 Randolph Road
Rockville
MD 20852;

Dear Mr. Burke: This is in reply to your letter to Dave Schmeltzer of this office date August 11, 1971.; In your letter you ask to be advised if it would be permissible unde the Tire Identification and Record Keeping Regulation (49 CFR 574 (sic) to use your own form, instead of the form supplied by the tire manufacturer, to report the required information to the tire manufacturer.; The regulation does not expressly provide that you must use the for supplied by the tire manufacturer to record the required information. However, from the manufacturer's point of view using a form other than the one he supplied would cause double work and extra expense. As the regulation is presently written this would be a matter between you and the manufacturer.; The problem you describe has been brought to the National Highwa Traffic Safety Administration'(sic) attention and methods of giving dealers who handle many different tire manufacturer's lines some relief are presently being considered.; Thank you for writing. Sincerely, Lawrence R. Schneider, Chief Counsel

ID: aiam4473

Open
Bill Hunt, Project Engineer Telex Communications, Inc. 8601 Northeast Highway 6 Lincoln, NE 68505; Bill Hunt
Project Engineer Telex Communications
Inc. 8601 Northeast Highway 6 Lincoln
NE 68505;

"Dear Mr. Hunt: This letter responds to your inquiry of November 3 1987, in which you enclosed a diagram to show the relationship between your company, Telex Communications, Inc. (Telex or your company), and a Telex customer you designated as Company XYZ (or your customer). As I understand your diagram, Telex manufactures a trailer which it sells to Company XYZ. Company XYZ then delivers the trailer to its subcontractors, Companies ABC and DEF, who install items such as generators and communications equipment. Your letter suggests that you are uncertain about your company's certification responsibility. It is your company's position that as an incomplete vehicle manufacturer, you should provide the document specified in 49 CFR 568.4(a). On the other hand, your customer asserts that as the incomplete vehicle manufacturer, Telex must assume legal responsibility for the incomplete vehicle under 49 CFR 568.7(a), and certify the vehicle's compliance under Part 567. On a number of occasions, you spoke with Joan Tilghman of my staff on the matters raised in your letter. On the diagram enclosed with your letter, you state that the trailers Telex delivered to Company XYZ are equipped with 'running gear, brakes, lights, etc.' Telex assigns a VIN, gross axle weight rating, and a gross vehicle weight rating to each trailer it delivers to Company XYZ. You are concerned because two contractors with whom you have no relationship add equipment to the trailer after you deliver it to your customer. First, having reviewed the drawing of the trailer and the narrative information in your letter, it is not clear to me whether your trailers are, in fact, incomplete vehicles. You may wish to provide me with information that more completely describes your trailer so that I may give a more definitive answer to your question. A photograph showing the trailer as it is delivered to Company XYZ would be helpful. However, I shall be as responsive as I can be given the information you supplied in your letter. If the trailers are incomplete vehicles, then Part 568 would not compel your company to certify the trailers' compliance with all applicable Federal safety standards. Under 568.7, Telex may elect to assume legal responsibility for all the certification duties and liabilities imposed on a manufacturer under the National Traffic and Motor Vehicle Safety Act, and affix the certification label as specified in 567.5(e). But if Telex decides against assuming certification responsibility, then it must supply the incomplete vehicle document specified in 568.4. If the trailers are completed vehicles which are converted to a different use by Company XYZ through its subcontractors, you must certify them irrespective of whether your customer contracts to have other equipment added to the vehicles after delivery. The fact that your customer contracts to have a generator and communications equipment added does not mean that the vehicle requires further manufacturing operations to perform its intended function. The determination of whether a vehicle requires further manufacturing operations to perform its intended functions is not a subjective inquiry into what use the particular person to whom the vehicle is delivered intends to make of the vehicle. In previous interpretations, we have explained that the question is whether the particular vehicle type (e.g., trailer, van) requires further manufacturing operations to perform the customary functions that an ordinary purchaser would expect of this vehicle type. For example, a van that is delivered to a dealer ready for road use is a completed vehicle, even if the dealer intends to send it to a van converter to have different equipment (seats, refrigerators, etc.) installed before selling the van to a retail customer. Similarly, the trailer your company delivers to Company XYZ is a completed vehicle if it needs no further manufacturing operations to perform the functions an ordinary purchaser would expect of a trailer. Under the National Traffic and Motor Vehicle Safety Act (Vehicle Safety Act), a complete vehicle manufacturer's certification responsibilities apply up to the vehicle's first purchase in good faith for purposes other than resale. It appears from your letter that Company XYZ purchases your trailers for purposes other than resale, and that after its purchase, Company XYZ subcontracts with two other companies to add a generator and communications equipment to the trailers. If my assumptions are correct, then the two subcontracting companies have no certification responsibilities under the Vehicle Safety Act, because they are modifying vehicles after their first purchase in good faith for purposes other than resale. The only limitations on the modifications those subcontractors can make to the trailers is set out in 108(a)(2)(A) of the Vehicle Safety Act (15 U.S.C. 1397(a)(2)(A)). That section states that: No manufacturer, distributor, dealer, or motor vehicle repair business shall knowingly render inoperative, in whole or in part, any device or element of design installed on or in a motor vehicle or item of motor vehicle equipment in compliance with an applicable Federal motor vehicle safety standard... If Company XYZ's subcontractors are 'manufacturers,' distributors,' 'dealers,' or 'motor vehicle repair businesses' within the meaning of 108(a)(2)(A), they may not remove, disconnect, or degrade the performance of safety equipment or designs that Telex installed in the trailers in compliance with an applicable Federal safety standard. I hope you find this information helpful. If you have any further questions on this subject, or wish to provide additional information about the particular relationships that were the subject of this letter, please feel free to contact Ms. Tilghman at this address or by telephone at (202) 366-2992. Sincerely, Erika Z. Jones Chief Counsel";

ID: aiam4189

Open
Mr. Lene Magnussen, Gatt Enquiry Point--Denmark, Danish Standards Assn., Aurehojvej 12, Postbox 77, DH-2900 Hellerup, Denmark; Mr. Lene Magnussen
Gatt Enquiry Point--Denmark
Danish Standards Assn.
Aurehojvej 12
Postbox 77
DH-2900 Hellerup
Denmark;

Dear Mr. Magnussen: Your telex No. 15615 to the National Bureau of Standards has bee referred to us for reply, since the National Highway Traffic Safety Administration (NHTSA) regulates the manufacture and sale of new motor vehicles and motor vehicle equipment.; You asked for information regarding our regulations fo 'superstructures for vans.' We understand that the 'superstructure' is a structure designed to be mounted in the cargo area of a van by the user, and consists of a roof, floor and sides, and 'windows of plexiglass and the rear window of tempered glass.' Based on the brief description, it appears that the item of motor vehicle equipment you manufacture is either a 'camper' or a 'slide-in camper.' In addition to other requirements applicable to you as a manufacturer of motor vehicle equipment, we have requirements which apply directly to manufacturers of slide-in campers, which I will discuss below. (The information provided in your telex only briefly described your product. If we have not correctly understood the nature of the 'superstructure,' please do not hesitate to contact us.); By way of background information, our agency is authorized, under th National Traffic and Motor Vehicle Safety Act (copy enclosed), to issue safety standards applicable to new motor vehicles and certain items of motor vehicle equipment. NHTSA, however, does not approve motor vehicles or motor vehicle equipment, nor do we endorse any commercial products. Instead, the Vehicle Safety Act establishes a 'self-certification' process under which each manufacturer is responsible for certifying that its products meet all applicable safety standards. This process requires each manufacturer to determine in the exercise of due care that its products meet all applicable requirements. The agency periodically tests vehicles and equipment items for compliance with the standards, and also investigates other alleged safety-related defects. If you or the agency determines that a safety-related defect or noncompliance exists, you are obligated to notify purchasers of your product and remedy the problem without charge. Manufacturers who fail to provide notification of or remedy for a defect or noncompliance may be subject to a civil penalty of up to $1,000 per violation. (A general information sheet describing your responsibilities under the Vehicle Safety Act is enclosed.); You as a manufacturer of motor vehicle equipment are responsible fo certifying compliance with all applicable motor vehicle safety standards. Federal Motor Vehicle Safety Standard No. 126, *Truck-Camper Loading*, sets requirements for a slide-in camper, which is a camper having a roof, floor, and sides, designed to be mounted on and removable from the cargo area of a truck. Standard No. 126 requires you to permanently label each camper with information including its maximum loaded weight. The standard also requires each camper to be furnished with an owner's manual that includes information on total camper weight, proper matching of a truck and slide-in camper, appropriate methods of camper loading, and how to determine the camper's center of gravity and where it should be placed in the truck cargo area.; Federal Motor Vehicle Safety Standard No. 205, *Glazing Materials* sets performance requirements for glazing materials used in new motor vehicles and glazing materials sold as items of replacement equipment, including slide-in and other types of campers. The standard establishes both performance requirements, including ones regulating the light transmittance and abrasion resistance of glazing, and labeling requirements applicable to the glazing used in your product. Copies of both Standard Nos. 126 and 205 are enclosed for your convenience.; In addition to the copies of the materials described above, I a enclosing copies of two procedural rules which apply to all manufacturers subject to the regulations of this agency. The first in (sic) 49 CFR Part 566, *Manufacturer Identification*. This rule requires your company to submit your name, address, and a brief description of the items of equipment you manufacture to this agency within 30 days after you import your products into the United States.; The other rule is 49 CFR Part 551, *Procedural Rules*. Subpart D o this regulation requires all manufacturers headquartered outside of the United States to designate a permanent resident of the United States as the manufacturer's agent for service of all process, notices, orders and decisions. This designation should be mailed to the Chief Counsel, National Highway Traffic Safety Administration, 400 Seventh Street, S.W., Washington, DC 20590, and must include the following information:; >>>1. A certification that the designation of agent is valid in for and binding on the manufacturer under the laws, corporate by-laws, or other requirements governing the making of the designation at the time and place where it is made,; 2. The full legal name, principal place of business, and mailin address of the manufacturer,; 3. Marks, trade names, or other designations of origin of any of th manufacturer's products which do not bear its name,; 4. A statement that the designation shall remain in effect unti withdrawn or replaced by the manufacturer,; 5. A declaration of acceptance duly signed by the agent appointed which may be an individual, firm, or U.S. corporation, and; 6. The full legal name and address of the designated agent.<<< In addition, the designation must be signed by a person with authorit to appoint the agent. The signer's name and title should be clearly indicated beneath his or her signature.; I have also enclosed an information sheet describing the Federal Moto Vehicle Safety Standards. Also enclosed is a description of how you can obtain copies of our motor vehicle safety standards and other regulations.; I hope this information is helpful. Please contact us if you hav further questions.; Sincerely, Erika Z. Jones, Chief Counsel

ID: aiam1671

Open
Mr. William A. Bertolini, President, Bertolini Engineering Co., Inc., P.O. Box 338, Montgomeryville, PA 18936; Mr. William A. Bertolini
President
Bertolini Engineering Co.
Inc.
P.O. Box 338
Montgomeryville
PA 18936;

Dear Mr. Bertolini: This responds to your October 17, 1974, letter to President Ford askin that the Federal government consider a delay of the effective date for Standard No. 121, *Air brake systems*, because of its cost to vehicle manufacturers and to their customers.; Standard No. 121 requires that newly- manufactured air-braked vehicle stop from speeds of up to 60 mph on wet and dry surfaces in the loaded and unloaded condition, without leaving a 12-foot-wide lane and without lockup of wheels above 10 mph. These performance requirements are based on a safety need for improved braking performance on air brake- equipped highway vehicles. Controlled stopping within the traffic lane is particularly important to tractor-trailer combinations to avoid 'jackknife' skids.; We have analyzed the costs and benefits to be gained in upgradin truck, bus, and trailer braking performance and have concluded that the savings in lives, injury, and property damage justify the incremental costs of this standard.; The standard only applies to new vehicles because our statutor authority to regulate motor vehicle safety does not extend to used vehicles (15 U.S.C S 1397(b)(1)).; As for a differential in performance between heavy and lighte vehicles, we already have issued a Standard No. 108-75 *Hydraulic brake systems*, which mandates comparable stopping performance for hydraulic-braked vehicles, effective September 1, 1975.; From a cost standpoint, it is noteworthy that proponents of increase size and weight limits for commercial vehicles rely, in part, on the increased braking performance of vehicles which meet Standard No. 121. A major reason for the larger vehicles would be to reduce the costs of transportation, and Standard No. 121 contributes directly to that goal.; Standard No. 121 has already been delayed for two years and we do no have plans to further delay the standard, for the reasons stated above.; Yours truly, Richard B. Dyson, Acting Chief Counsel

Request an Interpretation

You may email your request to Interpretations.NHTSA@dot.gov or send your request in hard copy to:

The Chief Counsel
National Highway Traffic Safety Administration, W41-326
U.S. Department of Transportation
1200 New Jersey Avenue SE
Washington, DC 20590

If you want to talk to someone at NHTSA about what a request for interpretation should include, call the Office of the Chief Counsel at 202-366-2992.

Please note that NHTSA’s response will be made available in this online database, and that the incoming interpretation request may also be made publicly available.