Simulator and Field Study of Green Lights on Truck-Mounted Attenuators in Missouri During Mobile Operations

Mobile work zones for various types of moving operations (e.g., striping, pothole patching, sweeping) are an important component in highway maintenance activities which have particular safety issues. To help mitigate the risk and severity of collisions, a truck-mounted attenuator (TMA) is attached to a construction vehicle, typically equipped with amber/white lights. Despite these visible warnings, collisions involving TMAs and traffic still occur. In an effort to improve upon the traditional amber/white lights, the use of green lights on TMAs was investigated. The study included the evaluation of four light-color configurations: amber/white, green only, green/amber, and green/white. Driving simulator tests obtained various driver behavior measures, including the first blinker distance, merge distance, work zone and arrow direction recognition distance, and disability glare. Vehicle speeds were captured in both a simulator study and a field study. In the simulator study, the use of the amber/white combination led to the highest work zone visibility but also created the greatest concern with disability glare. Although the green-only configuration led to the lowest disability glare, it also resulted in low visibility. The results showed an inverse relationship between visibility (awareness of work zone) and arrow board recognition (easy on eyes). Other findings from the field study include lower traffic speeds for the green light TMA and lower vehicle speeds for lower TMA vehicle speeds. Overall, the study showed that the four configurations had various tradeoffs and none stood out as clearly superior in terms of the performance measures.