Estimating vehicle speed by analyzing the acoustic frequency of dashboard camera sound.

Dashboard cameras are now widely distributed and help determine the cause of traffic accidents and vehicle speed. The simplest method to calculate the accident vehicle's speed uses a specific section's driving distance and time, determining the average speed. However, we cannot determine whether the vehicle was accelerating or decelerating. In addition, setting the reference point of the specific road section is difficult if the video is too dark or the resolution is too low. Therefore, this study aimed to calculate vehicle speed using sound data from dashboard camera videos. Herein, we suggest a method to calculate the speed of a vehicle in an accident by analyzing the engine sound frequency. Furthermore, our method was verified experimentally and in an actual case. We found that this method could obtain more information than other dashboard camera speed calculations, such as when the vehicle accelerates, decelerates, and shifts gears. However, torque converter slips increased error in the speed calculations. Therefore, we propose using the engine's sound obtained from dashboard camera videos to calculate vehicle speed if the torque converter slip is not severe.

Pedestrian accident analysis with a silicone dummy block.

When a car is parked in an inclined plane in a parking lot, the car can roll down the slope and cause a pedestrian accident, even when the angle of inclination is small. A rolling car on a gentle slope seems to be easily halted by human power to prevent damage to the car or a possible accident. However, even if the car rolls down very slowly, it can cause severe injuries to a pedestrian, especially when the pedestrian cannot avoid the rolling car. In an accident case that happened in our province, a pedestrian was injured by a rolling car, which had been parked on a slope the night before. The accident occurred in the parking lot of an apartment complex. The parking lot seemed almost flat with the naked eye. We conducted a rolling test with the accident vehicle at the site. The car was made to roll down the slope by purely gravitational pull and was made to collide with the silicone block leaning against the retaining wall. Silicone has characteristics similar to those of a human body, especially with respect to stiffness. In the experiment, we measured the shock power quantitatively. The results showed that a rolling car could severely damage the chest of a pedestrian, even if it moved very slowly.