Mr. Robert Strassburger

Alliance of Automobile Manufacturers, Inc.

80 7th St., N.W., Suite 300

Washington, D.C. 20001


Mr. Michael X. Cammisa

Association of Global Automakers, Inc.

1050 K St., N.W., Suite 650

Washington, D.C. 20001


Dear Mr. Strassburger and Mr. Cammisa:


This responds to your January 28, 2016 letter requesting an interpretation as to whether sensors mounted in a bumper for purposes of crash mitigation qualify for the exception to the “no damage” provision of 49 CFR Part 581 (“the bumper standard”).  Based on the information you have provided, the National Highway Traffic Safety Administration (NHTSA) does not consider these sensors to be components of the bumper system.  These sensors would therefore be subject to the “no damage” provision of Part 581.  If, as an interim measure, an automaker wishes to deploy an AEB system that does not comply with Part 581, it may seek an exemption from that standard under 49 CFR Part 555.




On May 13, 2015, U.S. Department of Transportation Secretary Anthony Foxx announced that in order to ensure that the Department’s regulatory framework accelerates safety innovations, the Department would work to identify obstacles to safety innovations in its regulations to better understand where problems can be addressed internally and where we will need Congressional action.[1]  Secretary Foxx and NHTSA Administrator Dr. Mark Rosekind both have invited stakeholders to help with this effort by submitting requests for interpretation, for exemptions, and petitions for rulemaking. 


In response, you have submitted this letter on behalf of your organizations, the Alliance of Automobile Manufacturers (“Alliance”) and the Association of Global Automakers (“Global”), expressing concern that NHTSA’s bumper standard, codified at 49 CFR Part 581, could deter some auto manufacturers from more rapidly deploying a crash avoidance technology known as automatic electronic braking (AEB).[2]  You noted NHTSA’s announcement that, beginning with model year 2018, the agency would update its 5-Star Rating System to include AEB as a recommended safety technology, providing consumers with new information on technology with the potential to prevent rear-end crashes or reduce the impact speed of those crashes by automatically applying the brakes.[3]  Your letter suggests that “many currently available [AEB] systems” rely on sensors and other related AEB equipment mounted on vehicle bumpers and that sensors so positioned may not satisfy the minimum requirements of Part 581 for standard equipment.  Under Part 581, bumpers are subject to a pendulum test conducted at impact speeds of 1.5 and 2.5 mph, and a fixed barrier test conducted at an impact speed of 2.5 mph.  You state that the bumper standard, and NHTSA’s subsequent interpretations of it, are “inhibiting the timely conversion of this important technology from optional equipment to standard equipment as well as inhibiting the rapid deployment of enhanced crash systems including those that may include pedestrian detection and facilitate greater levels of vehicle automation.” 


We are pleased to respond to your letter.  By way of background information, NHTSA does not provide approvals of any motor vehicle or motor vehicle equipment.  Under the Vehicle Safety Act, it is a manufacturer’s responsibility to determine whether a motor vehicle complies with all applicable regulations, and to certify its products in accordance with that determination.  Manufacturers must also ensure that their products are free of safety-related defects.  The following interpretation represents the agency's opinion based on the information provided in your letter.


The Bumper Standard


Part 581 was issued in response to the 1972 Motor Vehicle Information and Cost Savings Act, in which Congress required DOT (by delegation, NHTSA) to prescribe bumper standards for passenger motor vehicles in order to “reduce economic loss resulting from damage to passenger motor vehicles involved in motor vehicle accidents.”[4]  NHTSA established the bumper standard at 49 CFR Part 581, which sets forth requirements for the impact resistance of passenger motor vehicles in low-speed front and rear collisions.  As authorized by Congress,[5] Part 581 applies only to passenger motor vehicles and not to multipurpose passenger vehicles[6] or low-speed vehicles.[7]


As mentioned above, Part 581 contains two basic damageability tests for bumpers and bumper components:  a “pendulum test” conducted at 1.5 and 2.5 mph, and a “barrier test” conducted at 2.5 mph.  Under each of these tests, the vehicle must meet certain damage criteria specified in § 581.5.  Your letter focuses on the damage criteria listed in §581.5(c)(8), which states that, following the bumper tests,


[t]he exterior surfaces shall have no separations of surface materials, paint, polymeric coatings, or other covering materials from the surface to which they are bonded, and no permanent deviations from their original contours 30 minutes after completion of each pendulum and barrier impact, except where such damage occurs to the bumper face bar and the components and associated fasteners that directly attach the bumper face bar to the chassis frame.

(Emphasis added.)  § 581.4 defines “bumper face bar” as “any component of the bumper system that contacts the impact ridge of the pendulum test device.” 


As you discussed in your letter, NHTSA has issued interpretations regarding what equipment may be part of the bumper face bar.  You expressed concern that those interpretations might indicate that bumper-mounted AEB sensors would not be part of the bumper face bar, and would therefore have to meet the damage criteria of § 581.5(c).  You also stated that the prior interpretations indicated NHTSA’s intent to decide whether particular components are part of the bumper system on a case-by-case basis, and asked that NHTSA conclude that bumper-mounted AEB sensors are in fact, components of the bumper system “because they help to perform a protective function with respect to frontal collisions,” and should therefore not be subject to the damage criteria of § 581.5(c)(8).


We agree that the question of whether particular components are part of the bumper system is properly decided on a case-by-case basis.  The answer to that question will be determinative of whether bumper-mounted AEB sensors need to meet the damage criteria of the bumper standard – that is, whether they must withstand the pendulum and barrier tests with no damage.


NHTSA has consistently interpreted the bumper face bar as including components that are integral parts of the bumper face bar, or are needed to attach the bumper face bar to the chassis frame, like shielding panels, tape strips, and certain types of grilles that, like the bumper, serve a load-bearing, protective purpose. [8]  On the other hand, NHTSA has found that bumper-mounted radar sensors, directional signals, and fog lamps are exterior surfaces that are not part of the bumper face bar and therefore are subject to the damage criteria.[9]  Here, NHTSA concludes that the bumper-mounted sensor devices that some automakers may seek to introduce as standard AEB equipment are not integral parts of the bumper face bar, or components and associated fasteners needed to attach the bumper face bar to the chassis frame.  Rather, they are more clearly akin to the other sensors and lamps NHTSA has previously found to be subject to the damage requirements of Part 581.  The fact that AEB (and bumper-mounted sensors that may be part of an AEB system) helps to mitigate damage in low-speed collisions does not make AEB sensors integral parts of the bumper face bar.  They would therefore be exterior surfaces subject to § 581.5(c)(8). 


Even if NHTSA were to conclude that bumper-mounted AEB sensors were an integral part of the bumper face bar, 49 CFR 581.5(c)(5) further requires that “[t]he vehicle’s propulsion, suspension, steering, and braking systems shall remain in adjustment and shall operate in the normal manner” after conducting the pendulum and barrier tests.  Your letter suggests that some bumper-mounted AEB sensors may “require realignment to facilitate proper system operation” following Part 581 testing.  Given that AEB systems on a vehicle are part of that vehicle’s braking system, in the event damage to an AEB sensor during Part 581 compliance testing causes any of these systems not to operate in a normal manner, the vehicle would not comply with Part 581.  If a vehicle manufacturer is unable to install an AEB system in a given passenger motor vehicle model that complies with Part 581, they may wish to petition NHTSA for a temporary exemption under 49 CFR Part 555.  Such an exemption may be an effective interim approach for some manufacturers until they are able to develop AEB systems that comply with Part 581, or until that regulation is amended (through rulemaking) to address bumper-mounted standards differently. 

We remain confident that your members will be able to speed the introduction of AEB into the marketplace in ways that comply with applicable vehicle requirements, and that bumper-mounted AEB sensors able to meet the damage criteria of Part 581[10] will build consumer confidence in these new systems.  We look forward to working with you further to speed the introduction of effective AEB systems throughout the fleet.


If you have any further questions regarding this issue, please feel free to contact me. 






Paul A. Hemmersbaugh

Chief Counsel


Dated: 7/13/16

Ref: Part 581


[1] See “Transportation Sec. Foxx announces steps to accelerate road safety innovation,” May 13, 2015, available at (last accessed Feb. 18, 2016).

[2] For more information about how AEB works, see (last accessed Feb. 18, 2016).

[3] See “U.S. DOT to add automatic emergency braking to list of recommended advanced safety technologies in 5-Star Rating System,” Nov. 2, 2015, available at (last accessed Feb. 18, 2016).

[4] This section of the Act is now codified at 49 U.S.C. Chapter 325.

[5] 49 U.S.C. 32501 and 32502.

[6] NHTSA defines multipurpose passenger vehicle (MPV) at 49 CFR 571.3.

[7] NHTSA defines low-speed vehicle (LSV) at 49 CFR 571.3.

[8] See 43 FR 20804 (May 15, 1978); 43 FR 40230 (September 11, 1978); letter to Kenneth M. Bush, American Suzuki Motor Corporation (March 9, 2004) (available at

[9] See 43 FR 40230 (September 11, 1978); letter to William Shapiro, Volvo Cars of North America (December 11, 1995) (available at 

[10] Again, we note that Part 581 applies only to passenger motor vehicles and not to MPVs or LSVs.