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TitlePotential effectiveness of seat belt interlocks
AuthorsSearson DJ, Anderson RWG
AbstractSeat belt interlocks are a vehicle safety technology that aims to increase seat belt usage by restricting the vehicle from being driven until occupants have fastened their seat belts. While this technology is generally not found on modern vehicles, it was made mandatory for vehicles manufactured in 1974 in the USA. Since then, little research has been done on the potential effectiveness of seat belt interlocks, but the literature does indicate the benefits of seat belt interlocks would outweight the costs. In this study three datasets were used to examine the vehicle age profiles of drivers who were not wearing a seat belt. These datasets included an observational study from 2009, hospital admission data from 2008-2010, and Coroner’s report data from 2008. In each dataset, the drivers who were not wearing a seat belt were driving older vehicles than those who were wearing a seat belt. Overall seat belt usage was 98% in the observational data, 89% in the hospital admissions data, and 66% in the Coroner’s data. A hypothetical scenario was considered in which seat belt interlocks were made mandatory in all new vehicle models from 2015 onwards. Under this scenario, the vehicle age profiles from each dataset were used to examine the time it would take for seat belt interlocks to be found in vehicles driven by those who would otherwise not be wearing a seat belt. These results were used to calculate a ‘strongest case’ estimate of the potential effectiveness of seat belt interlocks: by 2030 there would be a potential 2% reduction in injuries requiring hospital admission, and a 7% reduction in fatalities. By 2050 these values would approach 5% and 16% respectively. These reductions would apply on top of any casualty savings already made through enhanced vehicle technologies, infrastructure and regulations. Despite the relatively long time required for interlocks to reach maximum effectiveness, the low cost and complexity of introducing seat belt interlocks merits some encouragement, with some consideration given to after-market installation targeting users who are at high risk.
Report NumberCASR125
PublisherCentre for Automotive Safety Research
Publisher CityAdelaide
SponsorDepartment of Planning, Transport and Infrastructure
ISBN978 921645 63 1
Page Count20

Searson DJ, Anderson RWG (2013). Potential effectiveness of seat belt interlocks (CASR125). Adelaide: Centre for Automotive Safety Research.

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CASR125.pdfPublished Report in PDF format