The Advanced Crash Avoidance Technologies (ACAT) program initiated by the National Highway Traffic Safety Administration had two major overall objectives. These were to develop a standardized Safety Impact Methodology (SIM) tool to evaluate the effectiveness of advanced technologies in avoiding and mitigating specific types of vehicle crashes; and to develop and demonstrate objective tests that are used in the SIM to verify the safety impact of a real system. Honda and Dynamic Research Inc. (DRI) had been developing and applying such SIMs for several years and had a Cooperative Agreement with NHTSA to further develop a SIM in order to determine the feasibility of developing estimates of effectiveness for specific not-yet-deployed safety technologies in the absence of data from real world or field operational tests, and linking it to the results from objective tests. Objective tests that produce quantifiable, repeatable and reproducible results were developed to calibrate the level of correlation between the actual prototype of the proposed safety problem countermeasure and the math model of the prototype in a sample of technology-relevant accidents being addressed. The objective tests, which are based on dynamic reconstructions of a sub-sample of the technology-relevant NASS/CDS and PCDS real world accidents, included full-scale track tests with an expert driver using automatically guided soft targets (GSTs) of an automobile and a pedestrian, and driving simulator tests with a jury of typical drivers in order to include the effects of a sample of driver reactions to collision partners and to system warnings and interventions. Results from the objective tests were used to parameterize, calibrate and validate the SIM tool, which was then used to estimate US-level safety benefits. The SIM tool itself includes modules for automated reconstruction of conflict and crash scenarios; definition and sampling of technology-relevant crash types; dynamic simulation involving a human-vehicle-device-environmental model; and an overall safety effects estimator. An example application of the developed SIM tool and related objective tests were used to evaluate a Honda prototype Advanced Collision Mitigation Braking System (A-CMBS). Results indicated that the total collision and fatality effectiveness values for all police-reported crashes of the Honda A-CMBS were 8.3% and 3.7% respectively, and this corresponds to estimated safety benefits of 511,336 fewer collisions and 1,623 fewer fatalities at the US 2005 calendar year level. Overall, the ACAT-I project was successful in developing and demonstrating a methodology that can be used to estimate the safety benefits of a wide range of advanced crash avoidance technologies.
