NHTSA Targets Dangerous Headlight Glare With New Proposal

The National Highway Traffic Safety Administration is beginning a review of federal vehicle lighting standards to address headlight glare, modernize testing procedures and evaluate newer lighting technologies.

NHTSA Reviewing FMVSS 108

NHTSA plans to update Federal Motor Vehicle Safety Standard No. 108, which governs vehicle lighting and reflective equipment. The review will examine how headlight technology, vehicle height and lamp aim may affect glare for other road users.

The agency said the effort will bring together vehicle and lighting manufacturers, safety organizations, engineers, research institutions and other technical experts. NHTSA is using negotiated rulemaking for the first time in more than 25 years as it evaluates potential changes to the standard.

Areas under review include headlight glare, lower-beam photometry, headlamp aim and mounting height, automatic high-beam systems and testing procedures for newer lighting technologies.

Research Links Glare to Visibility Loss

Research cited by NHTSA found that an oncoming headlamp intensity of 1,000 candela can reduce a driver’s visibility distance by about one-third. At 7,000 candela, visibility distance can be reduced by roughly two-thirds during nighttime testing.

Glare is affected by the amount of light reaching another driver’s eyes and the direction of that light. A brighter headlamp with a precise cutoff and correct aim may direct less light into an oncoming vehicle than a dimmer lamp that is aimed too high.

The Insurance Institute for Highway Safety has also reported that modern headlights are brighter than those used in the past. IIHS research found that more than 90% of glare-related crashes occurred during daylight, when the sun can also be a significant source of glare. The institute has reported that vehicles receiving stronger headlight visibility ratings are involved in fewer crashes.

Adaptive Headlight Technology Included

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

NHTSA’s review will consider how such systems should be evaluated and whether existing requirements provide an appropriate regulatory path for them and other newer lighting technologies.

Rulemaking Process Ahead

NHTSA Administrator Jonathan Morrison said the collaboration is intended to examine possible causes of glare, update outdated requirements and support safety improvements. The agency’s negotiated rulemaking committee may include up to 18 representatives from the lighting and automotive industries, safety organizations, research institutions and engineering groups.

The announcement begins a process of research and recommendations. Any changes to federal lighting requirements would be developed through the agency’s regulatory process and would not take effect immediately.