Validation of Thums Human Model Throw Distance in Pedestrian Accident Scenarios

Increasing number of hit and run pedestrian accidents highlight the importance of accident reconstruction tools used in forensic investigations. The tools used nowadays are based on simplified assumption of particle – particle interactions (Searle’s model), or real life accidents (Happer’s model) which enable for prediction of the collision velocity based on pedestrian throw distance evidence obtained at the scene of the accident. Unfortunately, vehicle impact speeds can only be estimated as a range of velocities, as the Searle’s model forms a velocity corridor which widens with the increase of measured throw distance giving not accurate predictions. Development of computing architecture together with the advancement in computer human modelling opens the opportunity for bringing accident reconstruction studies to the next level and reducing the predicted velocities range. Nevertheless, to achieve this, the computer human models need to be reliable and robust. In this study, the Total Human Model for Safety (THUMS) was validated against analytical pedestrian throw distance models. The validation studies were performed with THUMS 4.0 at three different model stances and four different impact velocities (20, 30, 40 and 50 km/h) as well as three different stances, namely: standing, walking and running pedestrian. Analyses results were validated against Searle’s and Happer’s throw distance models. THUMS kinematics agreed well with the current accident reconstruction tools in terms of model behavior and predicted throw distance. The behavior of the THUMS model is different for low and high velocity impacts showing good agreement to the field data in terms of body kinematics. In particular, low impact velocities cause forward projection of the human body, while high impact velocities are characterised by the wrap trajectory of the THUMS model.