Accident Reconstruction for Rear Pole Impacts of Passenger Cars 2006-01-0899

While vehicular rear pole impacts are rare, they do occur, and can be very serious. General accident reconstruction methods, which derive vehicle stiffness values from rear barrier crash tests, over-predict the impact speed for these types of pole impacts.

Thirteen pole crash tests were run into the rear-ends of four 4-door, front-wheel drive sedans. Repeated crash testing was used on three of the vehicles. Two 1988 Acura Legends, which have one of the highest stiffness values from FMVSS 301 Rear Compliance crash testing, a 1988 Honda Civic, which has one of the softest rear-end stiffnesses, and a 1986 Ford Taurus were tested. The repeated crash testing methodology was validated using one of the 1988 Acura Legends and a previously published Ford Taurus test.

Residual crush was measured using maximum crush, point-to-point, longitudinal full-width, and longitudinal reduced-width methodologies. Crush was found to be linearly related to impact speed. The crash pulse when compared to barrier testing was longer and exhibited a later peak. Models were developed using linear regression to calculate crush energy or impact speed from the residual crush measurements. Methods were developed to transform rear-end B-values from barrier tests into B-values for use in rear pole impacts. The various models developed were compared using their coefficients of determination, standard deviations, and 95% confidence intervals to determine which models most closely predicted the impact speed. This analysis showed that models which used maximum crush had the best correlation.