On the impact of the regulatory frontal crash test speed on optimal vehicle design and road traffic injuries

Many countries have instituted New Car Assessment Programs (NCAPs) to help consumers compare the crashworthiness of automobiles on the market. These typically involve four or fi ve standardised tests, for which each new vehicle is rated on a 5-star scale. The ratings are available to customers and so, automakers strive for high scores by optimising their vehicle designs to the scenarios represented by the tests. The United States NCAP rates vehicles for frontal crashworthiness with a 56-kilometreper- hour (35-mile-per-hour) full-engagement barrier collision, which is a relatively severe test, considering that over 98% of crashes on US roadways occur at slower speeds. This paper presents a methodology for understanding the impact of the NCAP crash test speed on vehicle design and the consequent on-road safety outcomes, using physics-based simulations and optimisation tools. The results suggest that lowering the test speed from the current level to 48 kilometres per hour (30 miles per hour) may decrease the rates of serious injuries to vehicle occupants in the US by up to 21%.