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Mercedes-Benz, U.S.A. LLC; Receipt of Application for a Temporary Exemption From Federal Motor Vehicle Safety Standard No. 108

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National Highway Traffic Safety Administration (NHTSA), DOT.


Notice of receipt of application for a temporary exemption.


In accordance with the procedures of 49 CFR 555.6(b), Mercedes-Benz, U.S.A. LLC (“MBUSA”) has applied for a Temporary Exemption from S.5.5.10 of Federal Motor Vehicle Safety Standard (FMVSS) No. 108. The basis of the application is to facilitate the development and field evaluation of new motor vehicle safety feature providing a level of safety at least equal to that of the standard. We are publishing this notice of receipt of the application in accordance with the requirements of 49 CFR 555.7(a), and have made no judgment on the merits of the application.


You should submit your comments not later than November 7, 2005.

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George Feygin in the Office of Chief Counsel, NCC-112, (Phone: 202-366-2992; Fax 202-366-3820; E-Mail:

I. Background

MBUSA petitioned the agency on behalf of its parent corporation, DaimlerChrysler AG.[1] The petition seeks a temporary exemption from S5.5.10 of Federal Motor Vehicle Safety Standard (FMVSS) No. 108. In short, S5.5.10 specifies that with certain exceptions not applicable to this petition, all lamps, including stop lamps must be wired to be steady-burning.[2] In order to develop and evaluate an innovative brake signaling system in the United States, MBUSA seeks a temporary exemption from the “steady-burning” requirement as it applies to stop lamps. This system is currently available in Europe on the S-class, CL-class, and SL-class Mercedes vehicles.

MBUSA states that the system enhances the emergency braking signal by flashing three stop lamps required by FMVSS No. 108 during strong deceleration. In addition, after emergency braking, the system automatically activates the hazard warning lights of the stopped vehicle until it starts to move again or the lights are manually switched off. The petitioner states that this signaling system reduces the following drivers' reaction time by attracting their attention, and also enhances visibility of the stopped vehicle, thus helping to reduce the incidence and severity of rear end collisions.

NHTSA previously denied petitioner's request to permanently amend FMVSS No. 108 to allow flashing brake signaling systems. Among the reasons for the denial was the need for additional data on safety benefits of flashing brake lamps. The petitioner argues that granting this temporary exemption would allow them to provide the information NHTSA found lacking.

MBUSA requests a two-year exemption period. In accordance with the requirements of 49 CFR § 555.6(b)(5), MBUSA will not sell more than 2,500 exempted vehicles in any twelve-month period within the two-year exemption period. For addition details, please see the MBUSA petition at​search/​searchFormSimple.cfm, Docket No. NHTSA-2005-22653. The following (Parts II-VI) summarizes MBUSA's petition in relevant part.

II. Description of the New Motor Vehicle Safety Feature

The petitioner states that its brake signaling system provides two innovative safety-enhancing features.

First, three stop lamps required by FMVSS No. 108 flash at a frequency of 5 Hz in the event of strong deceleration. This occurs if the velocity is >50 km/h (31 mph) and at least one of the following conditions is met:

1. Deceleration is >7 m/s2; or

2. The brake assist function is active; or

3. The Electronic Stability Program (ESP) control unit detects a panic braking operation.

The petitioner states that the activation criteria ensures that the enhanced brake signals are only activated when truly needed. Thus, the brake lights will flash only in severe braking situations, and will flash at a relatively high frequency that allows for fast recognition. Further, using the panic brake signal from the ESP control unit as a trigger would activate the system only when the achievable Start Printed Page 58787deceleration is substantially smaller than the demanded one. Thus, the stop lamps would not flash in routine situations.

Second, after emergency braking, the system automatically activates the hazard warning lights of the stopped vehicle until it starts to move again, or the lights are manually switched off.

III. Potential Benefits of the New Motor Vehicle Safety Feature

The petitioner states that the brake signaling system provides important safety enhancements not found in a vehicle equipped with a traditional brake signaling system. First, the flashing system reduces the following driver's reaction time and encourages maximum deceleration of following vehicles. The petitioner expects especially strong benefits during adverse weather conditions and for inattentive drivers. Second, the activation of hazard warning lamps on the stopped vehicle also enhances vehicle recognition after it came to a complete stop. The petitioner believes that together, these features will help to reduce rear end collisions and improve safety.

The petitioner is aware of the agency's longstanding restriction on flashing stop lamps, in the interest of standardized, instantly recognizable lighting functions. However, MBUSA believes its system will be easily recognizable, and would not interfere with NHTSA's objectives.

IV. The Petitioner's Research and Testing

The petitioner states that the development of the innovative brake light system is based on careful research and testing. The activation criteria for the flashing brake lights were established with the help of a driver behavior study. The petitioner further states that field studies have demonstrated that the brake light system can significantly reduce driver reaction times.

MBUSA used a driver braking behavior study to understand how often rapid deceleration braking occurs in the United States. The study followed 96 subjects using 15 Mercedes-Benz vehicles equipped with a driver behavior and vehicle dynamics recorder. The study indicated that one emergency braking maneuver occurred for every 2291 miles driven. The study also suggested that, based on the criteria described in the previous section, only 23 out of 100,000 braking maneuvers would activate the flashing stop lamps. The petitioner concludes that the flashing brake light will occur rarely, which will help to avoid “optical pollution” and enhance the effectiveness of the brake light system.[3]

MBUSA sponsored additional field and driving simulator studies, which showed that “appropriately designed flashing brake lights significantly reduce drivers” reaction times and thus can reduce the incidence and severity of rear-end collisions.” [4] Specifically, the study compared reaction times in emergency braking situations among conventional brake lights, conventional brake lights combined with hazard warning lights, flashing brake lights with a flashing frequency of 4 Hz, and flashing brake lights with a flashing frequency of 7 Hz.

The petitioner states that the study showed that flashing brake lights reduce driver reaction time by an average of 0.2 seconds, which is a reduction sufficient to meaningfully reduce the number and/or severity of rear end collisions. MBUSA argues that even higher reduction in reaction time would occur under real-world driving conditions, where drivers are less focused on the driving task and subject to more sources of distraction. The study also showed positive effects from the flashing brake light signal under adverse weather conditions and in distraction situations. Finally, the test subjects expressed a preference for flashing brake lights when compared to other brake light symbols.

The petitioner states that the Japanese Ministry of Land, Infrastructure and Transportation conducted a study to evaluate the validity and operating conditions of two types of emergency brake light displays, one that flashes upon sudden braking, sand one that enlarges the lighting area of the brake lamps. The study found that flashing brake lamps reduced following drivers' response time in the drivers' peripheral fields of vision. The study also showed that shorter flashing intervals are more effective. Finally, the study indicated that an emergency brake light display that enlarges the lighting area is not as effective as a flashing brake lamp.[5]

V. How Will a Temporary Exemption Facilitate the Development and Field Evaluation of a New Motor Vehicle Safety Feature?

The petitioner states that it intends to monitor the exempted vehicles and study the effectiveness of the brake signaling system. First, MBUSA will gather information about rear-end collisions of vehicles equipped with the system. This information will be combined with the parallel results from the European fleet and, according to the petitioner, may prove to be valuable in evaluating the anticipated safety benefits of the new brake light system. Second, the test fleet may enable MBUSA to evaluate acceptance of the flashing stop lamps among the American public.

VI. Why Granting the Petition for Exemption Is in the Public Interest

As indicated above, the petitioner argues that granting the requested exemption from FMVSS 108 would enable them to continue developing and evaluating its innovative brake signaling system, thus contributing substantially to ongoing efforts to consider the effectiveness of enhanced lighting systems in reducing rear-end crashes. MBUSA believes that the system will help to significantly reduce following driver reaction times, thus reducing rear end collisions.

The petitioner also noted that rear end collisions are a significant traffic safety concern, particularly in dense traffic areas, and an important cause of rear end collisions is a following driver's failure to detect that a leading vehicle has performed an emergency braking action. MBUSA believes that an enhanced braking signal that alerts following drivers to urgent braking situations has the potential to significantly enhance safety.

VII. How You May Comment on This Petition

We invite you to submit comments on the application described above. You may submit comments [identified by DOT Docket Number NHTSA-2005-22653] by any of the following methods:

  • Web Site: Follow the instructions for submitting comments on the DOT electronic docket site by clicking on “Help and Information” or “Help/Info.”
  • Fax: 1-202-493-2251.
  • Mail: Docket Management Facility, U.S. Department of Transportation, 400 Seventh Street, SW., Nassif Building, Room PL-401, Washington, DC 20590.
  • Hand Delivery: Room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal Holidays.
  • Federal eRulemaking Portal: Go to Follow the online instructions for submitting comments. Start Printed Page 58788

Instructions: All submissions must include the agency name and docket number or Regulatory Identification Number (RIN) for this rulemaking. Note that all comments received will be posted without change to, including any personal information provided.

Docket: For access to the docket in order to read background documents or comments received, go to at any time or to Room PL-401 on the plaza level of the Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal Holidays.

Privacy Act: Anyone is able to search the electronic form of all comments received into any of our dockets by the name of the individual submitting the comment (or signing the comment, if submitted on behalf of an association, business, labor union, etc.). You may review DOT's complete Privacy Act Statement in the Federal Register published on April 11, 2000 (Volume 65, Number 70; Pages 19477-78) or you may visit

We shall consider all comments received before the close of business on the comment closing date indicated below. To the extent possible, we shall also consider comments filed after the closing date. We shall publish a notice of final action on the application in the Federal Register pursuant to the authority indicated below.

(49 U.S.C. 30113; delegations of authority at 49 CFR 1.50. and 501.8)

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Dated: October 4, 2005.

Stephen R. Kratzke,

Associate Administrator for Rulemaking.

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1.  For more information on MBUSA go to

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2.  See S5.5.10 of 49 CFR § 571.108. Turn signal lamps, hazard warning signal lamps, school bus warning lamps must be wired to flash. Headlamps and side marker lamps may be wired to flash for signaling purposes. Motorcycle headlamps may be wired to modulate.

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3.  Driver behavior research is described in Attachment A of the petition.

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4.  The study was conducted by Dr. Joerg Breuer and Thomas Unselt.

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5.  This study is described in greater detail in Attachment D of the petition.

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[FR Doc. 05-20277 Filed 10-6-05; 8:45 am]