Why is the FHWA concerned about the visibility of traffic signs at night?
One of the FHWA’s primary missions is to improve safety on the nation’s roadways. Approximately 42,000 men, women, and children have been killed on American roads during each of the past eight years. While only one quarter of all travel occurs at night, about half of the traffic fatalities occur during nighttime hours. During daylight hours, drivers have a number of visual cues, such as shoulders, pavement markings, overhead and post-mounted signs, roadside vegetation, guardrails, fences, and buildings, to make navigation easier. Although factors like intoxication and fatigue also contribute to the disparity between day and night crash rates, it is well known that darkness reduces the visual cues available to the driver. Unless they are illuminated or made from retroreflective materials, the traffic control devices and other visual cues that are readily available to drivers during daylight hours are usually more difficult to see at night. Adequately maintained retroreflective signs are
