Evaluation of Speed Monitoring Displays for Work Zones in Las Vegas, Nevada

Speed monitoring displays (i.e., speed trailers) have been evaluated in many states for reducing vehicular speeds in work zones. This study evaluated the enhancements to speed trailers regarding message size, the use of flashing, and the presence of more than one speed trailer in work zones. Field tests were conducted at two sites in the Las Vegas, Nevada, area, and traffic data were collected for statistical analysis. Regression models were developed to estimate the speeding likelihood and vehicle speeds on the basis of the free-flow speed data. The results indicated that the size of displayed messages and the use of flashing did show significant impact on speeding likelihood and speed reduction for vehicles in work zones. The extent of the impact varied for vehicle classification, the lanes they were operating in, and the day or night in which they were deployed. This study recommended larger message size and the use of flashing signs for speed trailers. More than one speed trailer was recommended for additional speed reduction.