Nighttime Visibility Facts and Statistics
- For the last 25 years, 50% or more of the fatal crashes have occurred at night despite the lower volumes of traffic at night.
- Overall annual fatalities on US highways have declined from about 50,331 in 1978 to a plateau around 42,000 by the late 1990's.
- Crashes under dark conditions are higher than under dark conditions with lighting owing to the fact that there are many more miles of unlit road.
- Crashes during dawn and dusk are a relatively small portion of the fatal crashes that has remained fairly constant.
- There has been a drop in night fatalities, with a more pronounced decrease for the “dark” condition.
- Despite a long-term downward trend, the night crash rate is about three times higher than that during the day.
- There are likely to be more fatigued and intoxicated drivers during the nighttime periods.
- Visual cues that delineate the roadway alignment are greatly reduced at night, even when there is street lighting.
- Regulatory, warning, and guidance information provided by traffic control devices is compromised under dark conditions or when headlight illumination is less than optimal.
- Glare from opposing traffic can adversely affect the driver's ability to detect changes in the road alignment or to see traffic control devices.
- Adverse weather (e.g., rain, snow, fog) further reduces night visibility of the road, other traffic (including pedestrians & bicyclist), and TCDs.
- The driving population is aging and it is well known that visual acuity decreases as a person ages. Older drivers are therefore less able to see the road, traffic control devices, and other traffic at night.
See Driver Night Visibility Needs for more information
