The sensitivity of the calculation of ΔV to vehicle and impact parameters.

ΔV is frequently used to describe collision severity, and is often used by accident investigators to estimate speeds of vehicles prior to a collision, and by researchers looking for correlations between severity and outcome. This study identifies how ΔV varies over a wide range of input uncertainties allowing the direct comparison of different methods of input data collection in terms of their effect on uncertainty in the calculation of ΔV. Software was developed to implement this sensitivity analysis and was validated against examples presented in the CRASH3 manual. The findings are therefore representative of, and relevant to, commercially available tools such as CRASH3 and AIDamage. It is possible to measure the vehicle and collision parameters with sufficient accuracy to determine ΔV to a level of precision that is useful to predict occupant fatality. In many cases, ΔV is largely insensitive to the input parameter and category values or values determined from photographs may be used. A vehicle specific value of the stiffness parameter B should be used. Direct measurement of crush measurements and vehicle mass (including the best estimates of fluid loss) should be used. Similarly the mass of occupants and cargo should be measured directly rather than estimated from 50th centile values. Calculation of ΔV is sensitive to PDOF which should be measured with a precision of better than ±6°.