NHTSA Targets Dangerous Headlight Glare: What Drivers Should Know

The National Highway Traffic Safety Administration is beginning a review of federal vehicle lighting requirements to address headlight glare and update testing standards for newer lighting technologies. The review will focus on factors including beam intensity, headlight aim, mounting height, adaptive systems and LED lighting.

NHTSA to Review FMVSS 108

NHTSA announced Oct. 6 that it plans to modernize Federal Motor Vehicle Safety Standard No. 108, which governs vehicle lighting and reflective equipment. The agency’s review is intended to address potential causes of glare, update requirements that have not kept pace with newer technology and create a regulatory path for safety systems not fully covered by existing standards.

The agency is initiating its first negotiated rulemaking on vehicle lighting in more than 25 years. NHTSA is expected to consult with automakers, safety advocates, lighting and automotive engineers, human-vision experts and other industry stakeholders before making recommendations.

Key issues include the relationship between headlight focus, mounting height and glare, as well as requirements for lower-beam photometry, LEDs, automatic high beams and other light-sensing features.

Glare Involves More Than Brightness

Glare depends on how much light reaches another driver’s eyes, including the intensity of the beam in a specific direction. Headlight aim, mounting height, optical cutoff, vehicle pitch, lens condition, roadway grade and the observer’s position can all affect the amount of light directed toward another vehicle.

A high-output headlamp with a precise cutoff and proper aim may direct less light toward an oncoming driver than a lower-output lamp that is aimed too high. NHTSA’s review is expected to examine those combined factors rather than focus only on the type of light source.

Research from the Insurance Institute for Highway Safety has found that more than 90% of glare-related crashes occurred during daylight. The institute has also reported that modern headlights are brighter than those used in the past and that vehicles receiving stronger visibility ratings in its headlight evaluations are involved in fewer crashes.

Adaptive Headlights Already Authorized

In February 2022, NHTSA issued a final rule allowing automakers to install adaptive driving beam headlights on new vehicles. These systems can adjust portions of the high-beam pattern to reduce light directed toward occupied areas of the roadway while maintaining additional illumination elsewhere.

The agency’s latest review will consider how adaptive driving beams and other newer lighting technologies should be evaluated under updated federal requirements. NHTSA Administrator Jonathan Morrison said the effort is intended to investigate potential causes of glare, modernize outdated regulations and support the development of safety-improving equipment.