Estimation of the effect of improved average secondary safety of the passenger vehicle fleet on annual counts of serious injury for Australia and New Zealand : 1991-2006.

The aim of the present analysis is to develop an index of the average secondary safety of the passenger vehicle fleet in Australia and New Zealand and then quantify what effect improvements in secondary safety have had on the number of people seriously injured or killed due to road crashes. Police-reported crash data from five Australian states and New Zealand were used to define the secondary safety index. The secondary safety index was based on the point estimates of individual ratings from the 2008 update of the Vehicle Safety Ratings (Newstead, Watson & Cameron, 2008a). A baseline secondary safety index was also defined as being equal to the secondary safety index observed for the fleet in 1991. After estimating the annual number of seriously injured or killed occupants for each year in the period 1991-2006, the baseline secondary safety index was used to estimate how many occupants would have been seriously injured or killed if the secondary safety of vehicles in the fleet had not improved since 1991. The average crashworthiness of Australian passenger vehicles was estimated to be 4.5% in 1991, improving steadily over the next fifteen years to be 3.3% in 2006. It was also found that the secondary safety index did not vary greatly when disaggregated across the five Australian jurisdictions. If the secondary safety of the Australian fleet had not improved in such a manner, it is estimated that 39,000 additional cases of occupants being seriously injured or killed would have occurred over the period 1991-2006, which is 14.6% higher than the total number of serious injuries and fatalities observed during this period. When considering fatalities alone, the improved secondary safety of the Australian fleet is estimated to have saved 2,700 lives over the period 1991-2006. The average crashworthiness of the New Zealand fleet was estimated to be about 7.5% in 1991 and 4.2% in 2006. The improved secondary safety of the New Zealand fleet over this period was estimated to have resulted in approximately 12,600 fewer cases of seriously injured or killed road users. When considering fatalities alone, the improved secondary safety of the New Zealand fleet over the period 1991-2006 was estimated to have saved about 1,900 lives. (Author/publisher)