DEVELOPMENT OF RECONSTRUCTION PROCEDURE FOR POLE ACCIDENTS

The objective of the study is to develop a reconstruction procedure for pole accidents in which the struck pole was partially or completely fractured. Alternative reconstruction approaches were evaluated and an analytical model based on a three-phase collision sequence was selected for further development. The total vehicle velocity change is considered as the sum of three components: (1) crushing of vehicle prior to pole fracture, (2) partial or complete fracture of pole at its base, and (3) if breakaway occurs, acceleration of the segmented pole structure by the impacting vehicle. The velocity change due to vehicle crush is obtained from the CRASH reconstruction program. Base fracture energy required for partial or complete fracture for various pole types was extracted from results of pendulum tests available from the literature and used in the determination of vehicle velocity change due to pole fracture. Mathematical equations were developed for calculating the velocity change as a result of the pole inertial effect. Five full-scale crash tests were used in testing and validation of the reconstruction procedure. Results from film analysis of the crash tests were compared with those obtained from the reconstruction procedure and the correlation was good with an average deviation of approximately 6 percent underestimation.