# The Contact Phase in Vehicle-Pedestrian Accident Reconstruction
## 4 Results
At collision speeds of 5 m/s, for this type of vehicle, it is possible that the head-to-car body contact may not occur. These vehicles can cause more severe injuries because of the greater height at the front edge of the hood. In this case pedestrians, especially small pedestrians, are hit in the pelvis-abdomen area with the front end, as opposed to compact class cars where the pelvis and abdomen were hit by the hood. Figure 8: Carry distance for compact class vehicle. Figure 7: Example of collision, compact class vehicle, at (**a**) 5 m/s, (**b**) 10 m/s, (**c**) 15 m/s and (**d**) 20 m/s, with deceleration of 2.5 m/s2. The results by type of vehicle show, as indicated in Figure 11, the longest distances travelled by the pedestrian in contact with the car, until detachment from the car for the SM class. The maximum distance in this case is just over 4.3 m at 10 m/s, as seen in Figure 12. In this case, for 10 m/s speed, there is a great dispersion, as a function of impact speed, of the distances travelled during the contact phase. The minimum distance is 1.15 m at a collision speed of 5 m/s. For this class of cars, at low impact speeds, the pedestrian kinematics is wrap around, followed by the somersault and roof vault at 20 m/s. Figure 11: Impact phases for SM class vehicle. Figure 10: Example of collision for CSUV vehicle, at 5 m/s speed. Figure 9: Carry distance for CSUV class vehicle. Considering the time origin at the moment of impact between the bumper and the pedestrian's lower limb, the secondary collision occurs within the time range of 0.05 s to 0.245 s, and the detachment from the car within the time range of 0.125 s to 0.42 s.  
For executive class EC, as indicated in Figure 13, the maximum distance in this case is around 2.5 m at 20 m/s, as displayed in Figure 14. The minimum distance is 1.2 m at a collision speed of 5 m/s. For this class of cars, at low impact speeds, the pedestrian kinematics is wrap around, followed by the somersault after 10 m/s. Considering the time origin at the moment of impact between the bumper and the pedestrian's foot, the secondary collision occurs within the time range of 0.06 s to 0.24 s, and the detachment from the car within the time range of 0.105 s to 0.315 s.  
For all classes of vehicles, we observe a tendency to increase the distance covered during the contact phase, along with the increase in the impact speed. The posture of the pedestrian at the moment of impact generates the kinematics of his/her movement, but it does not significantly change the contact times or, implicitly, the distances covered, as seen in Figure 15.  
Figure 14: Carry distance for executive class vehicle. Figure 8:0 Impact phases for executive class vehicle. Figure 8:1 Pedestrian carrying distance for all class vehicles. Analyzing all the categories of vehicles subjected to simulations as a whole, we notice that as the deceleration increases at the moment of impact, the maximum values of the distance traveled by the pedestrian until the separation from the vehicle decrease, as seen in Figure 8:2  
For rainy conditions, the adhesion coefficient of the wheels has been changed to the value of 0.4, so the vehicle can brake with a maximum of 3.93 m/s\({}^{2}\). The simulations were run this way only for deceleration of 2.5 m/s\({}^{2}\), varying the impact speed. The coefficient of friction between the car and the pedestrian was reduced to 0.1, whereas the coefficient of friction between the pedestrian and the ground was reduced to 0.3. Following the simulations, the analysis of the contact force diagrams that appear on the main body segments of the dummy indicates that the detachment times from the passenger car resulted with a maximum variation of 9.38% for all the classes of vehicles studied. Expressed in distance covered, these variations have a mean with a maximum of 0.4 m. The simulations in wet weather show an increase in the separation times compared to those performed for dry asphalt. Examples of these diagrams are shown in Figures 16-20.