Dedicated short-range communications technology for freeway incident detection performance assessment based on traffic simulation data

An assessment of the use of dedicated short-range communications technology to perform travel time monitoring and automated incident detection on a segment of rural freeway is described. The assessment used the CorSim traffic simulation tool to simulate traffic and incidents on a segment of rural freeway. Output data from the simulation was subjected to postprocessing to convert it to probe and beacon data. An incident detection algorithm was developed by using a travel time threshold and a counter. An alarm was generated when a counter reached a preselected level. This algorithm was tested on selected data flies, and the results were used to identify the optimum values of the travel time threshold and the counter alarm level. With these optimum values, the algorithm was applied to the probe and beacon data to determine how quickly the system could detect various traffic incidents. The analysis showed that the system could provide rapid and reliable detection of incidents. During the simulation and analysis, several parameters were varied so that their effect on the system performance could be observed. Each parameter proved to have a significant effect on the detection time, and the observed effects were consistent with logical expectations. In general, the time to detect an incident was reduced in response to (a) increased traffic volume, (b) increased incident severity, (c) increased transponder population, (d) reduced reader spacing, and (e) reduced distance from incident to next downstream reader.