BACKGROUND: Roadway-operations equipment used for construction, maintenance, utility work, and other similar activities generally operate within roadway right of way. These vehicles and mobile equipment 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, warning lights are provided on the equipment to alert motorists of potentially hazardous situations. Amber warning lights have traditionally been used although lights of other colors are often added with the intent of helping the traveling public better see the equipment. Combinations of amber, blue, and white lights and other forms of warning lights (e.g., lighted bars, lighted "arrow sticks," strobe, LED, and alternating flashing) are used. There is a concern that this variety of lighting on roadway-operations equipment has evolved without adequate consideration of the effects on the awareness and responsiveness of motorists.
There are no widely accepted guidelines for selecting warning lights on roadway-operations equipment that consider the type of equipment, weather conditions, day- and night-time operation, color of vehicle, and other relevant factors. Research is needed to develop guidelines for use by transportation agency personnel in selecting and procuring lights that will substantially enhance motorist awareness.
OBJECTIVE: The objective of this research is to develop guidelines for selection and application of warning lights to improve the conspicuity and recognizability of roadway-operations equipment used for construction, maintenance, utility work, and other similar activities. Roadway-operations equipment shall include vehicles and mobile equipment used in these activities.
TASKS: Accomplishment of this objective will require at least the following tasks.
PHASE I: (1) Collect and review relevant literature, specifications and guidelines, research findings, current practices, and other information relative to selection and application of warning lights on equipment used in roadway operations. Motorist response and other criteria used in the selection process should also be identified and discussed. This information must be assembled from published and unpublished reports, contacts with transportation agencies and industry organizations, and other domestic and foreign sources.
(2) Based on the information gathered in Task 1, identify and discuss the factors related to the design and selection of warning lights. These factors would include, but not be limited to, type and purpose of vehicle; day-time and night-time operations; weather conditions (e.g., snow, rain, fog, and dust); light details (e.g., color, type of light source, configuration and intensity of lights, flash patterns and parameters, location of lights on vehicles, and durability); color of the vehicle and markings on it; and distinguishability from emergency response vehicles. (3) Assess the relevance and importance of the factors identified in Task 2 to the selection and application of an effective lighting system, and develop a prioritized list of these factors. Also, identify those factors recommended for further research in Phase II. (4) Prepare an updated, detailed work plan for Phase II that includes investigations for addressing the factors recommended in Task 3 and developing the desired guidelines. (5) Prepare an interim report that documents the research performed in Phase I and includes the updated work plan for Phase II. Following review of the interim report by the panel, the research team will meet with the project panel. Work on Phase II of the project will not begin until the interim report and the Phase II work plan are approved by the NCHRP.
PHASE II: (6) Execute the plan approved in Task 5. Based on the results of this work, develop and validate guidelines for the selection and application of warning lights on vehicles and mobile equipment used in roadway operations. The guidelines shall be prepared in a format that will facilitate consideration and adoption by AASHTO and implementation by highway agencies. The guidelines will include the technical information necessary for developing procurement specifications. (7) Submit a final report that documents the entire research effort. The report shall include an implementation plan for moving the results of this research into practice.
Status: The project is complete. The final report has been received; copies have been distributed to Program sponsors (state departments of Transportation). The report has been published as NCHRP Report 624.