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Sun glare

When the low sun lines up with a road, drivers can be blinded for seconds. Research ties glare to more crashes, including with people walking and biking.

This page is a draft. Every fact links to its source, so you can check it yourself.

Right after sunrise and right before sunset, the sun sits low in the sky. On a road that points toward the sun, a driver can be blinded. A person in a crosswalk, a rider in a bike lane, or a red light can disappear in the glare.

When and where it happens

• Glare is worst when the sun is less than about 20 degrees from where the driver is looking. That is roughly the first hour after sunrise and the last hour before sunset. (SWOV road safety institute)
• Roads that run east and west get the most glare. Drivers heading east face the morning sun. Drivers heading west face the evening sun. A study in Arizona found glare was more likely to cause crashes on east-west roads than on north-south roads. (Mitra, Safety Science, 2014, as summarized in Ma and others, 2019)
• The same Arizona work found glare crashes at intersections were more likely in the morning and in fall and winter. (Ma and others, 2019)

What the research shows

• Rear-end and side crashes at signals. In Arizona, glare was linked to more rear-end and angle crashes at signalized intersections. (Ma and others, 2019, summarizing Mitra 2014)
• People walking and biking. In Japan, crashes with people walking or biking at intersections were more likely when the sun was low in the driver's direction. (Ma and others, 2019, summarizing Hagita and Mori 2014)
• Deaths. A study of over 100,000 pedestrian crashes in Taiwan found people hit in glare were more likely to die. The effect was stronger at sunset. (Ma and others, BMJ Open, 2019)
• More crashes overall. Dutch insurers reported about 20% more crashes with low morning sun. A study in Edmonton, Canada found about 30% more, mostly at intersections, linked to red-light running and failing to yield to people walking and biking. (SWOV)

How StreetCase checks glare

For each road, StreetCase uses the road's compass direction and the sun's position through the year to find the dates and times when the low sun lines up with the road in each direction. It then counts crashes that happened in those windows. This is a screening tool. A crash in a glare window does not prove glare caused it, and police reports do not always record glare.

Fixes that help

• Signal backplates with a reflective yellow border make the signal stand out against a bright sky. FHWA says they cut total crashes by about 15%. (FHWA)
• Lower speeds give a blinded driver more time and distance. See Speed and survival.
• A leading pedestrian interval puts people in the crosswalk before turning cars move. See Crossings.
• Trees and shade structures on the sunny side can block low sun at key crossings. (Ask the agency's engineers what fits.)

What to ask for

• "[Road] runs east-west and has crashes during glare hours. Please add retroreflective backplates at the signals at [intersections]."
• "Please review the crossing at [location] for sun glare in the [morning/evening] and add a leading pedestrian interval."

Last checked 2026-11-02.

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