• The FMCSRs specify the quantity, color, location, and position of lighting and reflective devices on motor vehicles.
• The FMVSS list the manufacturing specifications for original and replacement lamps, reflective devices, and associated equipment, including some technical data related to the location of certain lights and reflectors.
• All lamps must be securely attached, capable of being operated at all times, and not obscured by the tailboard, any part of the load, dirt, or other added vehicle or work requirement.

The purpose of the roadway illumination and vehicle conspicuity requirements are to:

• Reduce traffic accidents, injuries, and death by providing adequate illumination of the roadway.
• Enhance the visibility or attention-getting ability so that motor vehicles are seen and their signals clearly understood by other motorists and pedestrians, in both daylight and darkness (or any other conditions that might reduce visibility).

Applicable regulations

In general, the Federal Motor Carrier Safety Regulations (FMCSR) in Part 393 specify the quantity, color, location, and position of lighting and reflective devices on motor vehicles, while the Federal Motor Vehicle Safety Standards (FMVSS) in Part 571 list the manufacturing specifications for original and replacement lamps (including bulbs), reflective devices, and all associated equipment. Part 571 also provides some technical data related to the location of some lights and reflectors. This is achieved by 393.11 referencing 571.108 and stating that the vehicle must meet the applicable 571.108 standard that was in place at time of manufacture.

Lamps operable, obstructions prohibited

In general, all lamps must be securely attached and capable of being operated at all times. In addition, lamps and reflective devices must not be obscured by the tailboard, any part of the load, dirt, or other added vehicle or work equipment. However, the conspicuity treatments (i.e., retroreflective sheeting or reflex reflectors) on the front-end protection devices may be obscured by part of the load being transported. (393.9) In addition, all lighting devices must meet the requirements of Part 571 and the associated Society of Automotive Engineers (SAE) standards (when referenced).

List of required lighting and reflective devices

Table 1 in 393.11 contains a list of the various lighting and reflective devices required by 393.11 and the specifications as described in 571.108. The device specifications include quantity, color, location, position, height above the road surface, and the vehicles for which the device is required. The device list includes:

• Headlamps
• Turn signal (front/rear)
• Identification lamps (front/rear)
• Tail lamps
• Stop lamps
• Clearance lamps
• Reflex reflector, intermediate (side)
• Reflex reflector (rear/rear side/front side)
• License plate lamp (rear)
• Side marker lamp (front/intermediate/rear)
• Vehicular hazard warning signal flasher lamps
• Backup lamp
• Parking lamp