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Extensive modeling and simulation studies have been carried out to evaluate the performance of systems for avoiding run-off-road crashes. Results show that the effectiveness of in-vehicle crash avoidance systems depends on how well they can be tailored to specific vehicle, driver, and roadway characteristics. To this end, a major focus of these studies is the development of improved driver lane-keeping models based on statistical analyses of data collected in driving experiments conducted on highways, rural roads, and test tracks. In recent simulation studies using improved driver models, the performance of crash avoidance systems in tractor-trailers and passenger cars has been compared over a wide range of incipient run-off-road crash conditions. Heavy trucks present a greater challenge for run-off-road crash avoidance systems, because they slightly but frequently leave the lane even under controlled driving, and because they are less stable during recovery maneuvers.

Research in Intelligent Transportation Systems (ITS) has been increasingly focussed on the development of Collision Avoidance Systems (CAS). A CAS would reduce the incidence of collisions by providing warnings to the driver to take evasive action. Because single vehicle roadway departures, also known as Run-off-Road (ROR) events, are a cause of a significant portion of vehicle accidents and fatalities, an effective CAS for ROR can potentially improve highway safety dramatically. The development of performance specifications for CAS for ROR events is a part of an ongoing three-phase program for NHTSA (National Highway Traffic Safety Administration). This paper focusses on the development and application of a powerful simulation tool, RORSIM, for CAS assessments over a wide range of environmental, roadway, driver, vehicle and CAS operating conditions. The results of CAS effectiveness studies are presented.

An important part of ITS (Intelligent Transportation Systems, formerly IVHS) is the development of collision avoidance systems. These systems continuously sense the dynamic state of the vehicle and the roadway situation, and they assess the potential for a collision. When the system determines that an emergency situation might be developing, it warns the driver to take evasive action. Such countermeasure systems must be subjected to rigorous testing to ensure reasonable performance in all foreseeable circumstances and effectiveness in reducing the incidence of collisions. The efficiency and safety of testing can be greatly enhanced by using a dynamic simulation of a vehicle in near-collision situations and “equipping” the vehicle with a proposed collision avoidance system. This paper discusses the development and application of a time-domain simulation code based on a dynamic model of the driver/vehicle/counter-measure system.