EVU XXIV 2015-09 Glynn & Wood – Pedestrian Speed from Vehicle Damage

Pedestrian Speed from Vehicle Damage
Colin Glynn
Denis P. Wood


In car to pedestrian collisions the pedestrian speed can be a crucial determinant in the
potential for the driver to carry out an avoidance manoeuvre. In many such collisions there
is permanent contact damage to the vehicle due to the primary impact from the
pedestrian’s leg/lower body and the secondary impact from the pedestrian’s head. It has
been shown that a linear relationship exists between the ratio of the transverse to
longitudinal vehicle damage offsets (H/L) and the ratio of the pedestrian speed to car
speed (Vp/Vc). Madymo modelling has shown that the pedestrian stance (stage within the
pedestrian gait cycle) has a strong influence on the movement of the pedestrian during the
collision; with the struck leg leading the pedestrian will rotate such that the rear of the
pedestrian is presented to the car while with the struck leg lagging the front of the
pedestrian is presented. As such, it has been shown that the head contact location can be
used to determine whether the pedestrian’s struck leg was leading or lagging.

A Constant Inertial Property (CIP) pedestrian model has been applied in a Monte Carlo environment to
develop linear relationships between Vp/Vc and H/L for the cases where the struck leg is
leading, lagging or the struck leg position is unknown. Knowledge of the car speed allows
the pedestrian speed to be estimated. The case where there is no transverse offset
between primary and secondary damage locations, often incorrectly used as support for
the conclusion that the pedestrian was stationary at impact, is analysed.

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AutoreColin Glynn - Denis P. Wood
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