A government-commissioned study by transport consultancy TRL has found that brighter headlights are more likely to cause glare for drivers of oncoming vehicles. The research involved more than 50 hours of night-time on-road testing using a car fitted with a camera to measure headlight luminance and other sensors. Observers in the vehicle reported glare more often when higher luminance was recorded. Dr Shaun Helman, who led the TRL project, said: ‘This research provides compelling evidence that glare from vehicle lighting is a genuine issue for UK drivers, and can be measured in real driving conditions.’

The study also identified conditions that raise the risk of glare. Glare was more likely when the observing car was climbing an incline or navigating a right-hand bend, because the eyes are more likely to fall within the beam. Researchers also indicated a possible link between glare and larger vehicle shapes such as SUVs. The RAC surveyed 1,850 UK drivers as part of the work, with 33% saying they drive less at night or have stopped altogether because other headlights are too bright, and a further 22% wishing to reduce night driving but feeling they have no choice.

Reaction emphasises the need to balance safety benefits of bright headlights with glare reduction. Rod Dennis, RAC senior policy officer, said: ‘Having campaigned hard for this study, we welcome its findings which independently confirm what drivers have been telling us – that rather than being an imagined phenomenon, some bright headlights do cause a glare problem. While drivers clearly benefit from high-performing headlights, it’s important this doesn’t lead to others suffering the effects of dazzle, so a balance needs to be struck. It’s vital the report and its considerations are now reviewed carefully to put us on a path towards changes that ultimately benefit all road users.’ A Department for Transport spokesperson said: ‘We know headlight glare is frustrating for many drivers, especially as the evenings get darker. That’s why we commissioned this independent research to better understand the causes and impact of glare, and to help inform future negotiations on international vehicle standards.’ The DVSA is stepping up checks to intercept the sale of illegal retrofit headlamp bulbs, and anyone caught could face a fine of up to £2,500. IAM RoadSmart policy director Nicholas Lyes said: ‘While focus will be on amending international regulations of new vehicles, that doesn’t solve the issue with those cars on the roads today. The MOT test does provide for inspections of lights including intensity, but whether this is providing adequate safeguards for other motorists is debatable.’