NHTSA proposes optional cyan marker-lamp specifications and updated lighting-control rules for ADS vehicles, including trucks and buses; the proposal is not yet a final rule.
NHTSA announced the proposal on October 23
The National Highway Traffic Safety Administration announced a notice of proposed rulemaking on October 23, 2026 to modernize Federal Motor Vehicle Safety Standard No. 108. The signed proposal is dated October 22 and is identified as docket NHTSA-2026-1519, RIN 2127-AM70.
FMVSS 108 applies beyond passenger cars
The standard covers passenger cars, multipurpose passenger vehicles, trucks, buses, trailers other than specified exceptions, motorcycles and related replacement equipment. The proposal therefore matters to automated commercial-vehicle development as well as robotaxis and other passenger vehicles.
Cyan ADS marker lamps would be optional
NHTSA proposes specifications for cyan-colored Automated Driving System marker lamps on ADS-equipped vehicles. A manufacturer would not be required to install the lamps on every ADS vehicle. If the lamps are installed, the proposal would standardize attributes such as color, number, mounting location, activation, visibility and photometric intensity.
The lamp would communicate active ADS operation
The proposed marker lamp is intended to identify that the automated driving system is engaged in full control of the driving task without an expectation that an occupant is monitoring the roadway. NHTSA cites potential benefits for law enforcement and other road users while seeking to avoid inconsistent lamps that could cause confusion.
The proposal addresses vehicles without manual controls
For an ADS vehicle designed without a steering wheel, service-brake pedal or other manually operated driving controls, NHTSA proposes to narrow requirements tied specifically to hand- or foot-operated turn-signal, hazard-warning and headlamp beam-switching controls. The vehicle would still need a means to operate its signal lamps and switch headlamp beams.
Vehicles with manual controls keep the existing requirements
NHTSA says the proposed control changes would not alter the applicable requirements for a vehicle that has manually operated driving controls, even if that vehicle also has an ADS. The distinction is about vehicle design, not merely whether an automated feature is turned on during a particular trip.
Telltale requirements would follow the same distinction
The agency proposes to limit certain turn-signal and upper-beam telltale requirements to vehicles with manually operated driving controls and to use the term telltale consistently. A telltale is an in-vehicle visual indicator; it is different from the external cyan marker lamp proposed for communication with people outside the vehicle.
Headlamp testing would move beyond one fixed voltage
FMVSS 108 currently uses a 12.8-volt test specification for headlamps. NHTSA proposes to test integral-beam headlamps at a voltage specified by the manufacturer, reflecting LED and other long-life designs. Replaceable-bulb and sealed-beam headlamps would continue to use the existing 12.8-volt test under the proposal.
Vertical headlamp design would gain flexibility
The proposal would remove the rule that places the lower beam above the upper beam when the two are arranged vertically. Minimum and maximum mounting-height requirements would remain. NHTSA's preliminary view is that modern lighting can provide adequate illumination without preserving the older vertical-order requirement.
This is not a final lighting rule
The document is a notice of proposed rulemaking. It does not authorize a fleet to add a cyan lamp today as proof of federal compliance, does not require automated trucks to display one and does not remove current FMVSS 108 obligations. Final requirements could change after comments and agency review.
The public comment clock depends on Federal Register publication
The signed prepublication document states that comments will be due 30 days after publication in the Federal Register. On October 25, the document still directs readers to the forthcoming official version for the final date. Commenters should verify the published deadline in docket NHTSA-2026-1519 rather than calculating from the press-release date.
The action is separate from the negotiated rulemaking
NHTSA expressly distinguishes this proposal from the negotiated rulemaking announced earlier in October concerning other elements of FMVSS 108. The October 23 action has its own docket and defined amendments. Participation, schedule and subjects in the negotiated process should not be merged with this NPRM.
Carrier operating rules are not changed by the proposal
The proposal concerns vehicle manufacturing and equipment standards. It does not create motor-carrier operating authority, waive FMCSA maintenance or inspection duties, determine whether a human driver needs a CDL, or establish where an automated truck may operate. Those questions remain governed by separate federal, state and local requirements.
Primary-source note
This report is based on NHTSA's October 23 press release and the 66-page signed NPRM submitted for Federal Register publication under docket NHTSA-2026-1519. CDL Truck Pro has described the cyan lamps as optional, the document as proposed, and the comment deadline as pending official publication; it has not treated the action as an approved automated-truck deployment rule.
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Official sources
NHTSA: Vehicle lighting updates for automated vehicles, October 23, 2026NHTSA signed NPRM: Modernization of FMVSS No. 108 for ADS vehiclesRegulations.gov docket NHTSA-2026-151949 CFR 571.108: Lamps, reflective devices and associated equipmentCDL Truck Pro provides educational information. Confirm licensing, safety, tax, and regulatory requirements through current official sources and qualified professionals.