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Flashing emergency and warning lights are critical elements of public safety and traffic control during roadway incidents. These lights should not only alert drivers to their presence, but also should inform them of who and what is present on the scene, and should help to manage the responses of drivers as they navigate past the incident. First responder and driver safety depend upon all three of these functions, yet standards focus almost entirely on alerting drivers. A full-scale outdoor field study was carried out during daytime, during nighttime on dry pavement and during nighttime on wet pavement, using a mock-up roadside scene containing three police vehicles. The lights on the vehicles were adjusted to produce different levels of intensity, flash rate, and synchronization of lights across all three vehicles. In some cases, sequentially flashing lights were present.

Workers in construction and transportation sectors are at increased risk for work-related injuries and fatalities by nearby traffic. Barricade-mounted warning lights meeting current specifications do not always provide consistent and adequate visual guidance to drivers and can contribute to glare and reduced safety. Through an implementation of sensors and wireless communications, a novel, intelligent set of warning lights and a tablet-based interface were developed. The lights modulate between 100% and 10% of maximum intensity rather than between 100% and off in order to improve visual guidance and adjust their overall intensity based on ambient conditions. The lights can be synchronized or operated in sequential flash patterns at any frequency between 1 and 4 Hz, and sequential patterns automatically update based on global positioning satellite (GPS) locations displayed in the control interface.

Flashing warning lights and vehicle markings of various colors are used on a wide range of emergency and other service vehicles to help inform drivers about the presence of these vehicles and the types of situations that drivers are approaching. Although not applied consistently among all jurisdictions, the colors and performance of these visual elements are often selected to help communicate the type of scenario (such as red flashing lights to indicate an emergency vehicle, or yellow flashing lights to indicate a non-emergency service vehicle). Previous investigations have shown that flashing light colors, vehicle and marking colors, and flashing temporal characteristics (e.g., rapid versus slower flashing) can all affect a driver’s perception of whether a vehicle along the road is responding to an emergency situation or not.