Simulator evaluation of incident detection using VRC system

This paper reports on an analytical model which was developed to evaluate the detection of freeway incidents by drivers using a vehicle to roadside communications (VRC) system. The VRC system utilizes radio frequency communications between a tag installed in a vehicle and a reader installed on the roadside. A driver with a tag capable of digital messaging activation can report an incident to the responsible highway agency via the roadside reader. The FRESIM (freeway simulation) model was used to simulate shoulder and lane-blocking incidents occurring under various traffic flow rates. The proportion of tagged vehicles in the general vehicle population and the degree of the drivers´ reporting propensity were introduced as controlled variables. A binomial probability model was applied to determine the probability of an incident being reported by drivers who passed an incident. The results show that all simulated incidents were detected in a short time with high probability of detection. It was found that in periods of moderate to heavy traffic flow, more than 80 percent of the simulated incidents can be detected in less than two minutes if 1 out of 100 vehicles on a freeway has a tag. The detection rate improved to 100 percent when 1 out of 10 vehicles had a tag. It is noteworthy that at the end of 1995 approximately 1 out of 100 registered vehicles in the Houston, Texas metropolitan area had a tag