The faster a vehicle moves and strikes a pedestrian, the more likely it is to cause severe injury. The final outcome also depends on the height of the vehicle. Even speeds of 40 km/h in residential areas are considered high, as pedestrian injuries at such speeds can be quite serious. This was the conclusion of a study by the Insurance Institute for Highway Safety (IIHS), an independent nonprofit scientific and educational organization dedicated to reducing fatalities in the U.S.

To assess the risk of injury at different speeds, IIHS researchers examined 202 pedestrian-related accidents involving individuals aged 16 and older. The data came from two databases: one covering accidents that occurred in Michigan between 2015 and 2022, and another from accidents in California, New Jersey, and Texas in 2022. The researchers used photographs of the vehicles involved to determine hood height. They then examined the effects of speed, vehicle height, and injury severity.

They focused on front-end height because it determines the point of impact on a pedestrian’s body. It was found that the vehicle’s weight does not play a significant role in pedestrian accidents, as any vehicle, regardless of its type, is far heavier than a human.

Regardless of vehicle height, higher speeds were associated with increased injury risk in all cases. Pedestrians struck at 20 km/h had a 46% chance of sustaining at least a moderate injury, such as a broken bone or concussion, and an 18% chance of a severe injury, such as a fracture. At 55 km/h, the risk of moderate injury rose to 86%, and the risk of severe injury increased to 67%. Regarding fatalities, pedestrians struck at 40 km/h had only a 1% chance of dying from their injuries, but at 55 km/h, the risk climbed to 19%. At 80 km/h, the fatality rate exceeded 80%.

Overall, taller vehicle fronts increased the likelihood of both moderate and severe injuries to pedestrians. At 43 km/h, a medium-height car had a 60% chance of causing moderate injuries to a pedestrian and a 30% chance of causing severe injuries, while, by comparison, a pickup truck had an 83% chance of causing moderate injuries and a 62% chance of causing severe injuries.

The study’s findings indicated that 25 km/h can be considered a “safe” collision speed between a car and a pedestrian. At this speed, the risk of severe injury is 10% or less. The study also found that 40 km/h in a residential area is considered a high speed. Reducing speeds from 50 km/h to 40 km/h would decrease the risk of severe injury from 50% to 32%.

On the other hand, vehicle manufacturers can also play a role in preventing pedestrian accidents. They could, for example, modify the front-end designs of their vehicles to better protect pedestrians and equip their cars with more advanced automatic emergency braking systems that take control whenever they detect a potential collision with a pedestrian.