Roadway-operations equipment used by transportation agencies for construction, maintenance, incident response, and other similar activities generally operate on all types of roadways, during day and night hours, and under all weather conditions. To improve motorist and work-crew safety, equipment must be readily seen and recognized and, therefore, appropriate colors, retroreflective markings, and warning lights are provided on the equipment to alert motorists of potentially hazardous situations. Combinations of lights of different colors (e.g., amber, blue, and white) and other forms of warning lights (e.g., lighted bars, lighted "arrow sticks," strobe, LED, and alternating flashing), vehicle color, and retroreflective markings are used. However, there is a concern that this variety of color, retroreflective markings, and lighting on roadway-operations equipment and vehicles has evolved without adequate consideration of their effects on the awareness and responsiveness of motorists.
In 2008, NCHRP Project 13-02 developed Guidelines for the Selection and Application of Warning Lights on Roadway Operations Equipment (published as AASHTO Publication Code WL-1 and available as part of NCHRP Report 624). However, because of the significant technology changes and the apparent increased speeds, traffic volumes, and distracted drivers in recent years, there is a need to re-examine the many factors that influence the effectiveness of colors, retroreflective markings, and lighting applied to vehicles and equipment, and develop updated guidelines for use by transportation agency personnel in the procurement process, and thus enhance motorist awareness and safety.
The objective of this research was to develop guidelines, for consideration and adoption by AASHTO, for the selection and application of color, retroreflective markings, and lighting to vehicle and equipment that will effectively identify vehicles and equipment, and communicate their activities to the motoring public, and thus enhance safety. This research is concerned with transportation-agency roadway-operations vehicles and equipment used for construction, maintenance, incident response, and other similar activities.