ID: NCC-230927-001 FMVSS 135 - Telltale_ St. Pierre_ Canoo

June 7, 2024

Mr. Barry St. Pierre 

Sr. Homologation Engineer  

Canoo 

19951 Mariner Ave 

Torrance, CA 90503 

barry.st.pierre@canoo.com

Dear Mr. St. Pierre: 

I write in response to your September 12, 2023 email to the National Highway Traffic Safety Administration (NHTSA) asking for information on federal requirements for telltales in light vehicle brake systems. Please note that our answer below is based on our understanding of the specific information provided in your email correspondence. 

In responding to this request, NHTSA notes that the contents of this letter do not have the force and effect of law and are not meant to bind the public in any way. This letter is only intended to provide clarity regarding existing requirements under the law at the time of signature. 

Background 

NHTSA is authorized by the National Traffic and Motor Vehicle Safety Act (Safety Act, 49 U.S.C. Chapter 301) to issue Federal Motor Vehicle Safety Standards (FMVSS) setting performance requirements for new motor vehicles and new items of motor vehicle equipment. The Safety Act requires manufacturers to self-certify that their vehicles and equipment conform to all applicable FMVSS in effect on the date of manufacture. NHTSA also investigates safety-related defects. 

Your email correspondence seeks clarification of the requirement in 49 CFR § 571.135 S5.5.5(a) that visual indicators “shall have letters not less than 3.2mm (⅛ inch) high.” You state correctly that, if the telltale is the word “BRAKE,” it must meet the height requirement. You also ask about the specific proposed brake and ABS icon symbols pictured in your correspondence. In particular, you ask: (1) if a brake symbol includes the letter “P” as part of the symbol, whether it is sufficient for the symbol as a whole to meet the 3.2 mm height requirement of S5.5.5(a), or whether the letter “P” by itself must meet the height requirement; and (2) if an antilock braking system symbol includes the letters “ABS” as part of the symbol, whether it is sufficient for the symbol as a whole to meet the 3.2 mm high requirement, or whether the letters “ABS” by themselves must meet the height requirement. 

Discussion 

As you acknowledge in your correspondence, 49 CFR § 571.135 (FMVSS 135) S5.5.5(a) specifies labeling requirements for light vehicle brake systems. It states: 

Each visual indicator shall display a word or words in accordance with the requirements of Standard No. 101 (49 CFR 571.101) and this section, which shall be legible to the driver under all daytime and nighttime conditions when activated.
Unless otherwise specified, the words shall have letters not less than 3.2 mm (⅛ inch) high and the letters and background shall be of contrasting colors, one of which is red. Words or symbols in addition to those required by Standard No. 101 and this section may be provided for purposes of clarity. 

49 CFR § 571.101 (FMVSS 101), in turn, includes requirements for telltales and indicators. Section 5.2.1 states, in relevant part: 

[E]ach control, telltale and indicator that is listed in column 1 of Table 1 or Table 2 must be identified by the symbol specified for it in column 2 or the word or abbreviation specified for it in column 3 of Table 1 or Table 2. If a symbol is used, each symbol provided pursuant to this paragraph must be substantially similar in form to the symbol as it appears in Table 1 or Table 2. 

Table 1 of FMVSS 101 shows the required telltales for the items for which you request clarification: brake system malfunction and anti-lock brake system malfunction. These telltales have specific words or abbreviations that must be used as identifiers. Specifically, the word “Brake” must be used to indicate brake system malfunction. The words “Antilock” or “Anti-lock,” or the abbreviation “ABS,” must be used to indicate antilock brake system malfunction for vehicles subject to FMVSS Nos. 105 or 135. Unlike certain other items, Table 1 of FMVSS 101 does not permit the use of a symbol as an alternative to words or abbreviations to indicate either a brake system malfunction or an anti-lock brake system malfunction. Further, these required words or abbreviations must comply with the 3.2 mm height requirement of FMVSS 135 S5.5.5(a). 

NHTSA understands the symbols proposed in your correspondence to be separate from and additional to the required words or abbreviations discussed above. With this understanding, the two proposed symbols pictured in your correspondence would not be subject to the word height requirement laid out in FMVSS 135 S5.5.5(a), as they would be considered additional words or symbols used for clarification purposes. Accordingly, neither the symbols, nor the letters that are part of the symbols, would be required to be at least 3.2 mm. 

However, if a vehicle does not use Table 1’s required words or abbreviations as a telltale for the item in question, and instead only uses a symbol that does not contain the required words or abbreviations, then the vehicle does not meet the requirements of FMVSS 101 S5.2.1, regardless of the height of the symbol or the letter(s) in the symbol. 

Finally, we note that, as discussed above, one permissible telltale for an anti-lock brake system malfunction is the abbreviation “ABS.” Accordingly, if the symbol pictured in your letter that includes the letters “ABS” is the only telltale used in a vehicle to indicate an antilock system brake malfunction, then the letters “ABS” in that symbol must meet the 3.2 mm minimum height requirement in FMVSS 135 S5.5.5(a). It would not be sufficient for the symbol as a whole to meet this height requirement, because S5.5.5(a) specifically requires the “words” to meet the requirement. 

I hope this information is helpful. If you have any further questions, please feel free to contact Natasha Reed of my staff at this address or at (202) 366-2992.

Sincerely,
Adam Raviv
Chief Counsel

Dated: 6/7/24
Ref: Standard No. 135

ID: NCC-231121-001 Autoliv (Veoneer) Spotlight Interpretation 1

June 27, 2024

Richard Seoane 

VP Operations and Business Development 

Thermal Product Area 

Veoneer 

420 South Fairview Avenue Goleta, CA 93117 

Dear Mr. Seoane: 

This responds to your request dated October 10, 2016, concerning the application of Federal Motor Vehicle Safety Standard (“FMVSS”) No. 108, Lamps, reflective devices, and associated equipment, to a lighting system you describe in your letter. As I explain below, based on your description of the system we agree that it is supplemental lighting, but disagree with your assertion that it would not impair the effectiveness of any of the required lighting equipment. 

In responding to this request, the National Highway Traffic Safety Administration (NHTSA) notes that the contents of this letter do not have the force and effect of law and are not meant to bind the public in any way. This letter is only intended to provide clarity regarding existing requirements under the law at the time of signature. 

Description of the Marking Light and the Request for Interpretation 

In your letter, you request an interpretation of FMVSS No. 108 as applied to an auxiliary light designed to prevent nighttime crashes (the Marking Light). As you describe it, the Marking Light consists of two auxiliary spotlights operated independently of the headlighting system. The spotlights are mounted symmetrically about the vertical centerline of the vehicle, below the headlamps, and pointed down at a fixed angle. The Marking Light operates independently of the upper and lower beam headlamps to produce a narrow, white-light beam pointed down to highlight the path to an object (such as a pedestrian) in or near the forward roadway so that the driver can see it. The Marking Light is activated and controlled by Autoliv’s Night Vision System, which has an infrared camera that detects pedestrian, bicyclist, and animal hazards up to 100 meters in front of the vehicle. The Night Vision System alerts the driver with in-vehicle 

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Richard Seoane 

visual (e.g., head-up display icon and/or dash icon) and audible signals indicating activation of the Marking Light and directs the Marking Light to illuminate the path over the ground to the hazard to visually alert the driver of the presence and location of the hazard. The system does not engage vehicle steering or brakes. The Marking Light cannot be activated manually by the driver or continuously operated; it is activated only by the night vision system when a hazard is detected to assist the driver in seeing the hazard but does not assist the driver in seeing the roadway. You state that the Marking Light is disabled in the presence of oncoming and preceding traffic so that it does not glare drivers on a wet or shiny roadway. 

You explain your position that the Marking Light is a supplemental lamp, not a required lamp such as a headlamp. You then make a variety of different arguments (and provide data) to support your view that the Marking Light does not impair the effectiveness of any of the required lighting. We summarize these arguments in more detail where relevant in the discussion below. 

Applicable Requirements 

FMVSS No. 108, which is codified at 49 C.F.R. § 571.108, sets requirements for vehicle lighting. The standard requires a variety of types of lighting, depending on vehicle type and size, and specifies requirements for these required lighting elements. The standard also sets requirements (referred to as “if equipped” requirements) for some non-mandatory lighting devices, such as daytime running lamps. 

Lighting devices that FMVSS No. 108 does not require or regulate as “if equipped” lighting devices are considered supplemental (or auxiliary) lighting devices. Supplemental lighting is generally permitted as long as it does not impair the effectiveness of any of the lighting equipment required by the standard. See FMVSS No. 108 S6.2.1 (also referred to as the “impairment” provision). 

FMVSS No. 108 applies only to original equipment and lighting equipment manufactured to replace original lighting equipment required by FMVSS No. 108. The standard does not directly apply to supplemental lighting devices sold in the aftermarket. Instead, supplemental lighting offered as an aftermarket accessory is subject to the “make inoperative” prohibition (49 U.S.C. § 301222), which prohibits certain specified commercial entities (such as dealers or repair shops) from taking a vehicle out of compliance with an FMVSS. In applying the “make inoperative” prohibition to aftermarket accessory lighting, NHTSA typically asks whether the accessory lighting would impair the effectiveness of any required lighting. Generally, if an item of accessory lighting would not be permitted as original equipment, commercial entities will not be permitted to install the lighting as an aftermarket accessory for a vehicle in use. 

While the vehicle manufacturer has the legal responsibility under the National Traffic and Motor Vehicle Safety Act (Safety Act) to certify that the vehicle complies with FMVSS No. 108 and all other applicable FMVSS, as a practical matter, vehicle manufacturers generally insist that equipment manufacturers provide assurance that their products meet federal standards. The judgment of impairment is one made, in the first instance, by the person installing the device. That decision, however, may be questioned by NHTSA if it appears clearly erroneous. 

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Richard Seoane 

Discussion 

The threshold issue presented by your request is whether the Marking Light is part of the required headlighting system and thus subject to the requirements applicable to headlighting systems, or supplemental lighting that is regulated by FMVSS No. 108’s impairment provision. We agree with you that the Marking Light would be considered supplemental lighting. 

FMVSS No. 108 requires vehicles to be equipped with one of several permissible headlighting systems.1 Headlighting systems are comprised of headlamps and associated hardware. The purpose of headlamps is primarily to provide forward illumination.2 In determining whether lighting equipment that provides forward illumination is part of the required headlighting system or supplemental lighting, NHTSA looks at several factors. These factors have included, among other things: (1) where the lamp directs its light; (2) whether it uses a headlamp replaceable light source to emit a beam that provides significantly more light flux than supplemental cornering lamps or fog lamps; (3) whether the lamp is intended to be used regularly, or is limited to more narrow driving conditions and situations; or (4) whether there is a manual on/off switch.3 

None of our previous interpretations appear to have addressed a frontal lighting concept precisely like the Marking Light. We agree with you, based on the information you have provided us, that it is supplemental lighting because it is not intended to be used regularly, but is instead a narrow beam that is activated only when there is a hazard forward of the vehicle such as a pedestrian or animal near the roadway. 

Because the Marking Light would be considered supplemental lighting, it is permitted as long as it does not impair the effectiveness of any lighting equipment required by the standard. In its previous interpretation letters, NHTSA has identified a number of different ways that a supplemental lamp could impair the effectiveness of the required lighting.4 

With respect to the Marking Light, there are two types of impairment that are potentially relevant. One is the potential to confuse other drivers arising from the Marking Light’s color, location, or activation pattern.5 The other potentially relevant type of impairment is the potential for glare to other road users due to the intensity of the Marking Light. We address each of these potential types of impairment below. 

1 FMVSS No. 108 Table I-a; S10.
2 FMVSS No. 108 S4 (“Headlamp means a lighting device providing an upper and/or a lower beam used for providing illumination forward of the vehicle.”).
3 See Letter from Jacqueline Glassman, Chief Counsel, to [Redacted] (Jan. 21, 2004). Prior to the 2004 interpretation letter, NHTSA issued several interpretations concerning auxiliary driving beams in which the agency treated those lamps as supplemental lighting without expressly considering the issue. See, e.g., Letter from Erika Z. Jones, Chief Counsel, to P. Soardo, Instituto Elettrotecnico Nazionale (May 22, 1987). If the lamps in question in those earlier interpretations would be considered supplemental lighting under the factors set forth in the 2004 interpretation, they may be consistent with that later interpretation. There is not, however, sufficient information about the lighting systems at issue in those earlier interpretation letters to allow application of the factors from the 2004 interpretation. In any case, the 2004 interpretation has been, to date, NHTSA’s view of the issue.
4 See, e.g., Letter from Jonathan Morrison, Chief Counsel, to Paul Schaye, Pedestrian Safety Solutions (Sept. 9, 2019).
5 See id. 

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Richard Seoane 

Color and Location 

The impairment provision prohibits auxiliary lamp colors that are likely to confuse other road users.6 For auxiliary lamps located on the front of the vehicle, colors that could cause confusion include red (which could be confused with a tail lamp), green (which could be confused with a traffic signal), and blue (which could be confused with a law enforcement vehicle).7 

You state that because the Marking Light is white, it cannot be confused with a turn signal and would not conflict with the emergency (hazard) lamps or parking lamps. 

We agree that because the Marking Light is white and mounted below the headlamps, it would not likely be confused with the front turn signal (which is amber8) and would not conflict with the vehicle hazard warning (which consists of all required turn signal lamps flashing simultaneously9) or the parking lamps (which must be white or amber10). I therefore agree that the color and location of the Marking Light would not cause confusion with the vehicle’s signal lamps. 

Activation Pattern 

FMVSS No. 108 requires that all auxiliary lamps be steady burning except for auxiliary lamps that supplement required lamps that flash, such as turn signals.11 This requirement means that the lamp must be steady burning when activated, not that it is prohibited from being activated or deactivated automatically.12 However, the (de)activation of the lamp cannot be so frequent or random that the lamp would distract or confuse other road users. For example, a lamp that activates and deactivates on an extremely short time interval due to sensitivity to slight changes in conditions would not be considered steady-burning.13 NHTSA has also interpreted the steady- 

6 Id.
7 Id.
8 FMVSS No. 108 Table I-a.
9 Id. S6.6.2; S4 (definition of vehicle hazard warning signal flasher).
10 Id. Table I-a.
11 See, e.g., Letter from Jonathan Morrison, Chief Counsel, to Paul Schaye, Pedestrian Safety Solutions (Sept. 9, 2019); Letter from Anthony Cooke, Chief Counsel, to Kerry Legg, New Flyer, Inc. (Feb. 21, 2008). Before 2007, FMVSS No. 108 included an explicit requirement that, with certain exceptions (e.g., turn signal lamps), all lamps on a vehicle, including auxiliary lamps, must be steady burning. In 2007, NHTSA implemented an administrative rewrite of FMVSS No. 108 which, among other things, converted the blanket “steady burning” requirement (and its exceptions) into individual activation requirements for each type of required lamp. See 72 FR 68234 (Dec. 4, 2007). Although the reorganized rule no longer includes a blanket “steady burning” requirement, NHTSA stated in the preamble to the reorganized rule that its “rewrite of FMVSS No. 108 is considered administrative in nature because the standard’s existing requirements and obligations are not being increased, decreased, or substantively modified.” Id. Moreover, NHTSA continues to believe that flashing auxiliary lamps would impair the effectiveness of required lamps by distracting or confusing other road users.
12 See Letter from Jonathan Morrison, Chief Counsel, to Paul Schaye, Pedestrian Safety Solutions (Sept. 9, 2019).
13 See id. 

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Richard Seoane 

burning requirement to mean that headlamp intensity may modulate, but only if the changes in intensity are not detectable by the human eye.14 

You state that the Marking Light is steady burning in that it does not flash (cycle on and off). You state that the Marking Light is activated when the night vision system identifies a pedestrian, bicyclist, or large animal in or near the forward roadway as a hazard. When the object is no longer deemed a hazard, the night vision system switches off the Marking Light. We also understand that the intensity of the Marking Light does not modulate. 

We agree that, based on the facts represented to us in your letter, the Marking Light is steady burning and would therefore not violate the impairment provision in this respect. This conclusion assumes that the Marking Light does not activate and deactivate frequently (which could confuse or distract other road users) or change intensity while activated in a way that is detectable to the human eye. 

Brightness (Photometric Intensity) 

Supplemental lighting can also impair the effectiveness of the required lighting if it is so intense that it glares other road users15 or, relatedly, masks any of the required signal lighting.16 As a point of reference, we note that FMVSS No. 108 specifies two upper beam (or high beam) maxima, at H-V and 4D-V.17 The magnitude of the specified maxima depends on the type of upper beam system; for the purposes of this letter, we will compare the Marking Light to the highest specified maxima at each test point, which are 75,000 candela (cd) at H-V and 12,000 cd 

14 See, e.g., Letter from Stephen Wood, Acting Chief Counsel, to Kiminori Hyodo, Koito Manufacturing Co., Ltd. (Nov. 5, 2005); Letter from John Womack, Acting Chief Counsel, NHTSA, to Joe De Sousa (Mar. 10, 1994) (stating, in the context of a modulating motorcycle headlamp, that “there is no failure to conform if the modulating light from the lamp is perceived to be a steady beam”).
15 See, e.g., Letter from John Womack, Acting Chief Counsel, to Yoshiaki Matsui, Stanley Elec. Co., Ltd. (Sept. 20, 1995) (fog lamp supplementing lower beam) (“Finally, as a cautionary note, we believe that Stanley should evaluate the glare potential of the headlamp when the fog lamp and lower beam are operating simultaneously, as it is important to safety that oncoming drivers not be distracted or discomforted in the operation of their vehicles.”). Cf. Letter from Jacqueline Glassman, Chief Counsel, to Rusty Riggin, Willow Development (Aug. 2, 2002) (explaining that a supplemental rear cornering lamp could violate the impairment provision if it was so intense that it “create[d] distracting glare”).
16 See, e.g., Letter from Jonathan Morrison, Chief Counsel, to Paul Schaye, Pedestrian Safety Solutions (Sept. 9, 2019) (“NHTSA has in the past stated that auxiliary lamps that were so bright as to ‘mask’ adjacent required turning signal lamps would be prohibited due to impairment.”); Letter From Samuel Dubbin, Chief Counsel, to Richard Russell (Dec. 22, 1995) (“[W]e would regard the vehicle manufacturer’s certification as negated if the brightness and location of the auxiliary lamps were such as to affect an oncoming driver’s ability to perceive the front turn signals.”).
17 FMVSS 108 Table XVIII. The photometry requirements specified in Table XVIII consist of test points at which the intensity of the light is measured. The requirements at each test point consist of minima and/or maxima. The test points are defined with respect to an angular coordinate system relative to the headlamp. Thus, H-V identifies a test point zero degrees up and zero degrees down relative to the headlamp, and 4D-V identifies a test point 4 degrees down relative to the headlamp. See also Letter from Erika Jones, Chief Counsel, to Byung Soh, Target Marketing Systems (Sept. 13, 1988) (“Effectiveness may be impaired if the device creates a noncompliance in the existing lighting equipment or modifies its candlepower to either below the minima or above the maxima permitted by the standard.”); Letter from Erika Jones, Chief Counsel, to George Ziolo (Sept. 12, 1988) (vehicle equipped with two upper beam headlamp systems would violate the impairment provision because it would exceed the upper beam maxima at H-V and 4D-V). 

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Richard Seoane 

at 4D-V. We consider the upper beam maxima as proper comparators because the Marking Light, like the upper beam, is designed to activate when no other cars are nearby.18 Just as upper beam headlamps are subject to maximum intensity limits, even though they are designed to turn off in the presence of oncoming traffic, the same concerns apply to forward-facing auxiliary lighting. 

You argue in your letter that the Marking Light will not glare other road users or mask any of the required signal lighting. You state that the Marking Light is disabled in the presence of oncoming traffic, so that its downward angle does not glare other drivers on a wet or shiny roadway. You also state that because the Marking Light is low to the ground and produces very little light above the horizontal plane of the headlamps, it cannot glare another driver or pedestrians. You state that because of these features, the Marking Light does not impair an oncoming driver’s ability to perceive the front turn signals. In a meeting with our office, you also indicated that the spotlamps on each side of the vehicle are generally not additive (combined). 

You also provided data on the intensity of the Marking Light (an iso-candela plot) based on on-vehicle measurements at a test laboratory. The photometric testing indicates that the Marking Light’s maximum intensity is 113,440 cd (at approximately four degrees down). You noted that the test setup resulted in higher estimated light intensities than what would be more accurately estimated by a goniometric component test conducted in a properly designed component lamp goniometry facility with appropriate stray light control. 

We believe that the Marking Light would violate the impairment provision because it would exceed—dramatically—the maximum permissible brightness of upper beams at 4D-V. This extreme intensity is a concern even if the Marking Light beam is aimed at a downward angle and the system is designed so that the light is disabled in the presence of oncoming and preceding vehicles, because it could still glare other motorists if the vision system does not correctly detect an oncoming or preceding vehicle and prevent the Marking Light from activating. This glare could happen, for example, if the vehicle crests the top of a hill when another vehicle is approaching, the vehicle encounters another vehicle at an intersection without detecting the other vehicle approaching from the side, or if the Marking Light reflects off wet pavement. 

We recognize that the photometric test setup led to overestimates of the Marking Light’s intensity. Nevertheless, the Marking Light is so intense that a more accurate estimate would likely still greatly exceed the upper beam maximum. We also note that the Marking Light’s intensity dramatically exceeds not only the upper beam maximum at 4D-V (12,000 cd), but also the maximum allowed for any individual upper beam headlamp (75,000 cd at H-V). This intensity presents a risk that other road users could be subject to significant glare. 

Conclusion 

I conclude that the Marking Light would be prohibited by the impairment provision in FMVSS No. 108 with respect to the Marking Light’s intensity at 4D-V.
18 FMVSS No. 108 S4 (upper beam defined as “beam intended primarily for distance illumination and for use when not meeting or closely following other vehicles”). 

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Richard Seoane 

If you have any further questions, please contact John Piazza of my staff at (202) 366-2992. 

Sincerely,
ADAM RAVIV
Adam Raviv Chief Counsel

Dated: 6/27/24
Ref: Standard No. 108

ID: NCC-241028-001 Interp Response - Volvo Trucks - FMVSS 121 Air Brake Reservoirs 01.16.2025

January 16, 2025

Mac Bradley Principal Engineer 

Volvo Group Trucks Technology 

Volvo Group North America LLC 

7900 National Service Road 

Greensboro, NC 27409

Re:    Interpretation of Air Brake System reservoir requirements under Standard No. 121 

Dear Mr. Bradley: 

This responds to your letter dated May 23, 2018, on behalf of Volvo Group North America LLC regarding the air brake system reservoir requirements in Federal Motor Vehicle Safety Standard (FMVSS) No. 121, S5.1.2. You describe a technology where an air dryer feeds the service reservoir directly, without the use of a separate supply reservoir or a condensate drain valve. You asked whether technology that you find to be “demonstratively more effective than a supply reservoir or automatic drain valve” may be used to comply with S5.1.2’s requirements. This letter responds to that request. 

In responding, the National Highway Traffic Safety Administration (NHTSA) notes that the contents of this letter do not have the force and effect of law and are not meant to bind the public in any way. This letter is only intended to provide clarity regarding existing requirements under the law at the time of signature. 

Section 5.1.2 requires that each truck and bus shall have:  

One or more service reservoir systems, from which air is delivered to the brake chambers, and either an automatic condensate drain valve for each service reservoir or a supply reservoir between the service reservoir system and the source of air pressure. 

S5.1.2 provides explicit reservoir requirements. Without either an automatic condensate drain valve or a supply reservoir, a vehicle would not comply with S5.1.2. The air dryer technology you suggest includes neither a condensate drain valve nor a supply reservoir. Although you suggest that this new technology is at least equally effective at removing water from compressed air, the standard is specific in its equipment requirements. We cannot by interpretation remove the requirements set forth in express terms in the regulatory text.1 

1 See, e.g., Letter to R.W. Hildebrandt, Bendix Corp. (May 30, 1980), available at www.nhtsa.gov/interpretations/nht80-241 (finding non-compliance where the air brake system may comply with the alleged intent of FMVSS No. 121 but does not comply with the standard’s technical requirements). 

The Notice of Proposed Rulemaking you cited from 1996 did propose revising FMVSS No. 121 to require a means of automatically removing moisture and contaminants from the air system and to delete the requirement for a supply reservoir. See 61 F.R. 56652 (Nov. 4, 1996). However, after consideration, NHTSA terminated that rulemaking, opting for further study of the requirements and test procedures for air drying and cleansing equipment used in air brake systems. See 63 F.R. 14674 (May 26, 1998). 

NHTSA cannot amend its regulations by interpretation. The appropriate vehicle to present your arguments would be a petition for rulemaking to amend FMVSS No. 121. In such a petition, you would be free to rely on the data you shared regarding the efficacy of air dryers at removing water from compressed air in support of a such petition for rulemaking. 

I hope this information is helpful. If you have any further questions, please feel free to contact Evita St. Andre of my staff at this address or (617) 494-2767. 

Sincerely,
ADAM RAVIV

Adam Raviv Chief Counsel
 

Dated: 1/16/25
Ref: Standard No. 121

ID: NCC-230420-001 571.108 Angelina Twardawa Auxiliary Side Lamps Interpretation signed

April 16, 2025

U.S.Department of Transportation
National Highway Traffic Safety Administration
Office of the Chief Counsel
1200 New Jersey Avenue SE. Washington, DC 20590

Ms. Angelina Twardawa 4550 Gustine Ave
St. Louis, MO  63116
angelina@angiestrans.com 

Dear Ms. Twardawa: 

This responds to your letter, received December 5, 2022 in which you requested a letter of interpretation asking whether aftermarket auxiliary trifunctional side marker lights which illuminate red in the rear, amber in the side, and white in the front, and that attach to the rear of a 53-foot trailer on both sides are compliant with Federal Motor Vehicle Safety Standard (FMVSS) No. 108, Lamps, reflective devices, and associated equipment. We apologize for the delay in responding to your inquiry. Based on the information you provided in your letter, we have concluded that installing the device as described may conflict with FMVSS No. 108. However, an alternative color configuration should be permissible under that standard. 

Please note that our guidance below is based on our understanding of the specific information provided in your letter. The contents of this letter do not have the force and effect of law and are not meant to bind the public in any way. This letter is only intended to provide clarity regarding existing requirements under the law at the time of signature. 

Background 

NHTSA is authorized by the National Traffic and Motor Vehicle Safety Act (Safety Act, 49 U.S.C. Chapter 301) to issue FMVSS that set performance requirements for new motor vehicles and new items of motor vehicle equipment. The Safety Act requires manufacturers to self-certify that their vehicles and equipment conform to all applicable FMVSS in effect on the date of manufacture.
NHTSA also investigates safety-related defects. After first purchase of a motor vehicle or item of motor vehicle equipment other than for resale, section 30122 of the Safety Act requires that a manufacturer, distributor, dealer, rental company, or motor vehicle repair business not knowingly make inoperative any part of a device or element of design installed on or in a motor vehicle or motor vehicle equipment in compliance with an applicable motor vehicle safety standard. This letter represents NHTSA's opinion concerning whether your design, as you describe it, would be permitted under FMVSS No. 108 and section 30122.

In your letter, you state that the device is a trifunctional light that attaches to the side of the rear guard of a 53-foot trailer on both sides with an open-ended connector. The lights have a red light designated at the rear, amber light designated at the side, and a white light designated at the front. You note that the piece that attaches to the trailer is rubber and flexible so it will not break, and that the device is stationary. You state the purpose of the device is to assist drivers with backing up, lane changes, and other maneuvers by providing increased visibility of the trailer at night. You ask whether the described design is permitted (both with regards to the device overall and the described lighting configuration), and if it is how far the devices can extend. 

FMVSS No. 108 specifies requirements for original and replacement lamps, reflective devices, and associated equipment, including for trailers. For auxiliary lamps, the primary restriction imposed by FMVSS No. 108 is by S6.2.1, which states that "[n]o additional lamp, reflective device, or other motor vehicle equipment is permitted to be installed that impairs the effectiveness of lighting equipment required by this standard." Additionally, both original equipment and aftermarket lighting can run afoul of the "make inoperative" provision in 49 U.S.C. § 30122. These prohibitions bar installation by a manufacturer, distributor, dealer, rental company, or motor vehicle repair business of lamps that would impair the effectiveness of required lighting, but do not apply to the owner of a vehicle. We note that whether there is an impairment is determined in the first instance by the manufacturer of the vehicle (or the entity installing the aftermarket lighting) when it is certified as compliant with FMVSS No. 108. 

Typically, the impairment determination is made on a case-by-case basis and looks at four main characteristics of the auxiliary lamp to analyze whether it impairs the effectiveness of required lighting. These are the brightness (photometric intensity), color, location, and activation pattern of the lamp.1 This list is not exhaustive and other considerations may be relevant to the analysis. NHTSA has long stated that highway traffic safety is enhanced by the familiarity of drivers with established lighting schemes, which facilitates their ability to instantly recognize the meaning the lamps convey and respond accordingly.2 Therefore, we have long interpreted the impairment provision to prohibit auxiliary lamps that are colors which are likely to cause confusion to other road users.3 Additionally, auxiliary lamps must be located such that they would not interfere or be confused with the lamps required by our standards. For example, we have stated that two auxiliary 

1 This letter is limited to the information provided in your request. Your request did not state the activation pattern or intensity of the device, which can be relevant to determining if a device causes impairment. For the purposes of this letter, we assume without finding that these aspects of your device do not cause impairment. The following information is provided for your reference regarding these elements. Regarding activation pattern, NHTSA interprets FMVSS No. 108 to require that all auxiliary lamps be "steady burning," with the sole exception being auxiliary lamps that supplement required lamps that flash, such as turn signals. Letter to Paul Schaye (Sept. 9, 2019), available at htqJs://www.nhtsa.gov/interpretations/571108-ama-schaye-front-color-changing-light. Regarding intensity, NHTSA interprets the impairment provision to prohibit auxiliary lamps that are so bright as to obscure or distract from a vehicle's required lamps. For example, NHTSA has in the past stated that supplemental lighting can impair the effectiveness of the required lighting if it is so intense that it glares other road users or masks required signal lamps. See Letter to Rusty Riggin, Aug. 2, 2002, available at htqJs://www.nhtsa.gov/interpretations/24179ztv, (explaining that a supplemental rear cornering lamp could violate the impairment provision if it was so intense that it "create[d] distracting glare"). Letter to Mark Wallach (Oct. 17, 2006) available at htqJs://www.nhtsa.gov/interpretations/wallach3.
2 Letter to Robert Clarke (July 28, 2005), available at htqJs://www.nhtsa.gov/interpretations/gID0255l3.
3 As an example, for auxiliary lamps located on the front of vehicles, these colors include red, which could be confused for a taillamp or stop lamp, and green, which typically conveys the message that one may proceed forward and could therefore impair required lighting that indicates caution. Letter to Paul Schaye (Sept. 9, 2019), available at htqJs://www.nhtsa.gov/interpretations/571108-ama-schaye-front-color-changing-light See also, Letter to Kerry Legg (Oct. 19, 2006), available at htqJs://www.nhtsa.gov/interpretations/leggl.

lamps located next to the three-lamp trailer identification lamp cluster would detract from the purpose of the cluster.4    '

For lighting relevant to your inquiry, FMVSS No. 108 requires that trailers have two amber side marker lamps as far to the front as practicable and two red side marker lamps as far to the rear as practicable. Trailers 30 feet or longer must also have amber intermediate side marker lamps and reflex reflectors on each side located at or near the midpoint between the front and rear side marker lamps.5, 6 

Discussion 

We now turn to your inquiry. Your lamp is not required equipment, and you correctly observe that it is auxiliary or supplemental lighting.7 Therefore, we turn to the question of impairment and look to the characteristics discussed. The factors which appear most relevant to your inquiry are the location and color of the lamps, which we analyze together. Due to the color and location of the lamp as described in your letter, it is likely to impair the effectiveness of the side marker lamps required to be installed on trailers by FMVSS No. 108, and, if installed by you or another entity subject to the "make inoperative" prohibition as aftermarket equipment, could make inoperative lighting required by FMVSS No. 108.8 However, an alternative color scheme would be permissible under FMVSS No. 108. 

Regarding side marker lamps, FMVSS No. 108 requires that intermediate side marker lamps be amber, and rear side marker lamps be red. Your design notes that your device will be mounted at the rear and that the side of the device will have amber lights. Therefore, in driving conditions
with poor visibility, such as at night or in heavy weather, your device may impair the effectiveness of the required intermediate side marker lamps by confusing nearby drivers about whether it indicates the rear or middle of the trailer, which could lead to unsafe driving decisions. 

4 Letter to Robert Clarke (July 28, 2005), available at htt;ps://www.nhtsa.gov/inter_pretations/gf00255l3.
5 We also note that S6.l.3.l of FMVSS No. 108 requires that each lamp, reflective device, and item of associated equipment must be securely mounted on a rigid part of the vehicle. The purpose,of this requirement is to ensure that lamps and reflectors do not sway in the wind on rigid hinges or flexible mud flaps when the vehicle is in motion. Letter from Frank Burndt to Dietmar K. Haenchen, (date unavailable), available at https://www.nhtsa.gov/inter_pretations/aiam3320. S6.l.3.1 is organized in S6.1 ofFMVSS No. 108, which contains requirements applicable to required lamps, reflective devices, and associated equipment. Although this provision does not explicitly apply to auxiliary lamps, an auxiliary device that is not securely mounted to a rigid part of the vehicle may impair the effectiveness ofrequired lighting because the motion of the light could distract drivers.  We have assumed for the purposes of this letter that your device is securely mounted to a rigid part of the vehicle and encourage you to ensure that this is the case.
6 49 CFR 571.108 Table 1-b. 49 CFR 393.11, which you referenced in communication with my staff, which requires commercial motor vehicles operated by motor carriers to be equipped with such lighting, contains similar specifications for color and placement of side marker lamps.
7 Your request describes your device as a "side marker lamp." Side marker lamps are a type of required equipment under FMVSS No. 108. Because your device is not required lighting, to avoid confusion this letter does not refer to your device as a side marker lamp.
8 Section 30122 applies to any "manufacturer, distributor, dealer, rental company, or motor vehicle repair business." We assume, for the purposes of this letter, that you are subject to this provision. 

Our opinion is based on the location and color of the lights as described in your letter. An alternative color scheme, with a red light facing the side in place of the amber light, is unlikely to have the same risk of impairing the effectiveness of the side marker lamps because it would
correspond to the color required for the required side marker lamps installed on each side as far to the rear as practicable, close to where you plan to install the device. We also encourage you to consider designs which mitigate any risk that a forward-facing white light could be perceived as a headlamp by other road users. 

Finally, you inquired about how far out the devices may extend from the trailer. NHTSA's regulations do not contain requirements specific to this question. Vehicle width is regulated by the Federal Highway Administration, who's regulation states that no State shall impose a width limitation of more or less than 102 inches (except Hawaii) for vehicles operating on the National Network.9 Five items are excluded regardless of how far they extend beyond the exterior of vehicles; rear view mirrors, turn signal lamps, handholds for cab entry/egress, splash and spray suppressant devices, and load induced tire bulge. Other excluded devices are: all non-property carrying devices or components at the front of a semitrailer or trailer, devices that do not extend more than 3 inches beyond each side or the rear of a vehicle, devices needed for loading or unloading that do not extend more than 24 inches beyond the rear of the vehicle, and aerodynamic devices that do not extend more than 5 feet beyond the rear of a vehicle, provided they have neither the strength, rigidity nor mass to damage a vehicle that strikes a trailer so equipped from the rear and provided also that they do not obscure tail lamps, turn signals, marker lamps, identification lamps, or any other required safety features, such as hazardous materials placards or conspicuity markings.10 

We also note that, because it is an item of motor vehicle equipment subject to the requirements of the Safety Act, it must be designed free from defects regarding motor vehicle safety. Additionally, truck tractors and trailers operated commercially in interstate commerce are subject to the regulations of the Federal Motor Carrier Safety Administration (FMCSA). Finally, States may have laws applicable to certain motor vehicle lighting. We are unable to advise you on those laws, but you should ensure your system complies with any and all applicable State laws.

We hope you find this information helpful. If you have further questions, please contact Eli Wachtel of my staff at (202) 366-2992.

Sincerely,

Peter Simshauser Chief Counsel

Dated: 4/16/25
Ref:  Standard No. 108
 

9 23 CFR 658.15.
1°FHWA Vehicle Size and Weight Q&A, available at https://ops.fhwa.dot.gov/freight/sw/fags/qa.cfin?categ01y=8. For
more excluded devices, see 23 CFR 658.16 and Appendix D to 23 CFR 658.