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SHINING A LIGHT

Practical Caravan

February 2026

Transport research company TRL has published the results of its study into headlight glare, but does it shed any clarity on the issue? Here, Paul Critcher shares the key points

A few months ago (in issue 492), we reported that transport research company TRL was conducting a study into headlight glare.

The study was commissioned and funded by the Department for Transport (DfT) in response to growing concerns from transport safety groups, driving organisations such as the RAC and individual drivers, around the perceived dangers from bright headlamps.

Since that report was commissioned, headlight glare has remained on the political agenda, including a debate in parliament at the end of October, following which the Government pledged to include the issue of dazzling headlights in its forthcoming Road Safety Strategy.

Now, with the publication of the study, 'Glare from vehicle lighting on UK roads', we report on its findings.

What was the aim of the study?

The project sought to gather data to understand the extent to which glare from headlights may occur in driving, and to understand potential root causes. Key research questions posed by scientists included understanding whether luminance at driver eye height was higher than the regulatory maximum; what factors most predict self-reported glare; and what factors most predict levels of luminance at driver eye height when driving.

Luminance is defined by the study as 'the measure of luminous intensity per unit area of light travelling in a particular direction. It is measured in candelas m-2 and may be thought of as akin to our everyday understanding of brightness'.

How did they do it?

The research broadly fell into two areas: on-road data collection of luminance and glare data, and a survey with a nationally representative sample of UK drivers.