Lower Extremity and Brake Pedal Interaction in Frontal Collisions: Sled Tests

A series of eight sled tests was conducted using Hybrid III dummies and cadavers in order to examine the influence of foot placement on the brake pedal in frontal collisions. The brake pedal in the sled runs was fixed in a fully depressed position and the occupants' muscles were not tensed. The cadaver limbs and the Hybrid III lower extremities with 45° ankle and soft joint-stop were extensively instrumented to determine response during the crash event. Brake pedal reaction forces were measured using a six-axis load cell and high speed film was used for kinematic analysis of the crashes. Four right foot positions were identified from previous simulation studies as those orientations most likely to induce injury. In each test, the left foot was positioned on a simulated footrest, acting as a control variable that produced repeatable results in all dummy tests. Each of the different right foot orientations resulted in different loads and motions of the right leg and foot. None of the cadavers sustained lower limb injuries in any of the tests, and the dummy tests did not produce axial force or tibia index values above proposed injury thresholds. Although no lower limb injuries were observed, the brake pedal did influence foot behavior and it could increase the risk of injury if occupant bracing, intrusion, and other parameters were incorporated into the testing.