Effectiveness of Stationary Police Vehicles with Blue Lights in Freeway Work Zones

Work zone safety affects both drivers and construction workers. Two main safety measures for reducing work zone crashes and their severity have been to reduce the vehicle speeds in work zones and to increase the separation between the vehicles and the workers. This project attempted to assess the effectiveness of deploying stationary police vehicles with flashing blue warning lights in freeway work zones. The effectiveness was evaluated based on (1) reductions in average vehicle speeds, (2) reductions in vehicle speeding, and (3) changes in vehicle lane use. Vehicle speed and lane use data were collected at two freeway work zones in Florida, including a static work zone on I-4 near Daytona Beach and a dynamic work zone on I-75 near Gainesville. Data were collected for two weeks prior to the deployment of a police vehicle, two weeks during which a police vehicle with flashing lights was stationed at the work zone, and two weeks following the removal of the police vehicle. For the static work zone on I-4 in which there was with 1-lane closure (out of three), it was found that the average speed within the work zone was reduced by 4.4 mph following the deployment of police vehicle, and by 1.4 mph following the removal of the police vehicle. The deployment of police vehicle was also found to reduce vehicle speeding by 20%. While the deployment of police vehicle with flashing lights was found to shift only a very small percentage of vehicles away from the work zone, the result was not considered reliable because it was skewed by a large percentage of vehicles that pre-positioned themselves for a downstream off-ramp exit. For the dynamic work zone on I-75 which included both 2-lane and 2.5-lane closures (out of three), it was found that the average speed within the work zone with 2-lane closure was reduced by 3.8 mph following the deployment of police vehicle, and by 2.7 mph following the removal of police vehicle. The deployment of police vehicle was also found to reduce vehicle speeding within the work zone by about 16%. In the case with 2.5-lane closure, the average speed within the work zone was reduced by 2.8 mph following the deployment of police vehicle, and by 3.1 mph following the removal of police vehicle. The latter result was not considered reliable as it was derived based on very limited data. The deployment of police vehicle with 2.5-lane closure was found to reduce vehicle speeding by 10%.