Simulation of Traffic Crashes Using Cell Based Microsimulation

The deterioration of the safety of operation, coupled with the persistent increase in rearend crashes, is of great concern in finding accurate and realistic methods of modeling traffic flow and preventing traffic crashes. For some decades safety evaluation methods have relied on analysis of historical crash data. Since crashes are random and rare events and, in most cases, are independent events, it is difficult to find a sufficient number of crashes on a road section in a relatively short time period (e.g., a month or even a year). Thus, multi-year collection of crash data is used in safety analysis. Another safety evaluation method that has been practiced though in small scale is traffic conflict techniques (TCT). The advantage of using TCT in safety evaluations is the ability to test or study a safety strategy or improvement applied on the roadway facility in a relatively short period of time compared with traditional methods, which are dependent on crash data. However, use of TCT is not popular; perhaps because it needs extensive resources to collect, extract, and analyze conflict information. Moreover, like crash data analysis, use of TCT also makes concerned authorities reactive to the problem by responding to the crashes that have already occurred. Therefore, alternative proactive safety evaluation techniques that can improve the quality of traffic safety evaluation are needed at this time. One way of using proactive safety evaluation techniques and thus become more preventive than reactive towards dealing with the overall safety problem is to utilize the capability of traffic micro-simulation to assess safety on highways through examination of hazardous vehicle movements in the traffic stream. Using micro-simulation predictive methods, it may be possible to diagnose safety problems and apply appropriate remedial measures, rather than waiting until a crash occurs to remedy the problem. This means, a hazard can be early identified and possibly corrected before implementation of highway projects. In addition, the use of simulation tools to evaluate the safety of a traffic system can be advantageous because such tools provide extensive results for any study area within a relatively short time along with other traffic operational measures like level of service, delays, travel times, and capacities.