The aim of this study was to evaluate the effectiveness of ESC systems in reducing crash risk in Australia and New Zealand. This was a follow up to an earlier evaluation, with the present study making use of a greater quantity and range of crash data to employ an improved induced exposure method for controlling the effect of confounding factors. More data also meant that effectiveness could be measured in terms of reductions in serious injury crashes and effectiveness could be measured for specific types of crashes, such as rollover crashes and head on crashes. Crash data from New Zealand and five Australian states, collected as part of the Used Car Safety Ratings project were analysed and consisted of 439,543 vehicles without ESC and 27,252 vehicles with ESC, with the latter group comprising of 175 different models. The overall crash reduction estimates of this study were in general similar to those previously estimated. The effect of ESC on all types of crashes leading to driver injury was a significant 8% reduction in risk. ESC was associated with a significant 8% increase in the risk of multiple vehicle crashes, but this effect was not evident when restricted to crashes that resulted in the driver being injured. ESC was effective at preventing single vehicle crashes (by 28% for all severities and 32% for crashes leading to driver injury) and particularly effective at preventing rollover crashes. When fitted to 4WDs, ESC reduced the risk of rollover crashes by 82%. However, unlike studies from other countries, the results of this evaluation suggested that there was a trend that ESC was less effective at preventing serious single vehicle crashes than less serious single vehicle crashes. The reason for this is not clear but it is possible that in Australasia serious single vehicle crashes are not occurring in circumstances where ESC can successfully intervene after driver input, for example when the driver is asleep. Investigating whether the effectiveness of ESC may be mitigated by a risk compensation effect was suggested as a topic for future research. (Author/publisher) This project was funded as contract research by the following organisations: Road Traffic Authority of NSW, Royal Automobile Club of Victoria Ltd, NRMA Motoring and Services, VicRoads, Royal Automobile Club of Western Australia Ltd, Transport Accident Commission, New Zealand Transport Agency, the New Zealand Automobile Association, Queensland Department of Transport and Main Roads, Royal Automobile Club of Queensland, Royal Automobile Association of South Australia, South Australian Department of Transport Energy and Infrastructure and by grants from the Australian Government Department of Infrastructure and Transport and the Road Safety Council of Western Australia.
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