The work zone speed advisory system (WZSAS) is designed to provide real-time speed advisory information to drivers by means of portable CMSs strategically located in advance of diversion points upstream of a work zone. This study evaluated the effectiveness of the WZSAS in encouraging traffic diversion when there was congestion in the work zone. The system was evaluated using data collected from the control system?s logs, field studies, user surveys, and system observations. Traffic demands were estimated from traffic flow and density data observed at the two camera locations during time periods before and after the deployment of the WZSAS system. The comparison between the "before" and "after" demands was made using data from every three-hour peak flow period during the study. It was found that the total peak-period demands did not change significantly in response to the speed messages. The WZSAS system did not significantly increase vehicle diversion under the traffic conditions observed during the study period. However, it should be noted that the system might be more effective under heavier traffic demands and more severe congestions. (Author/publisher)
Abstract