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. The research project was undertaken to evaluate the effectiveness of warning lights on roadway maintenance vehicles with the goal of establishing guidelines for the application of the lighting system on the vehicle. The research included an evaluation of the lighting parameters that define the performance in terms of glare and vehicle detectability as well as an evaluation of the lighting systems in adverse weather and in a dynamic setting. This report presents recommended guidelines for the selection and application of warning lights on roadway operations equipment. The recommended guidelines address the physical, functional, and performance requirements of the lighting system, recognize that the lighting system on these vehicles must be designed and laid out with consideration to the planned or expected vehicle usage, and provide technical information for use in developing procurement specifications for specific applications.