A law enforcement officer may not pull over a vehicle traveling 5 or 10 mph over the speed limit. However, that seemingly minor increase could mean the difference between life or death for a pedestrian.

Vehicle speed is just one of the many factors in the equation that determines the severity of injuries. Here is a list of circumstances that affect how devastating the accident could be between a vehicle and a pedestrian.

  1. Speed

The Insurance Institute for Highway Safety points out that faster speeds mean longer stopping distances, so the very act of speeding makes striking a pedestrian with a vehicle more likely. Most residential streets have limits of 20 or 25 mph, but even at 17 mph, a pedestrian has a 10% risk that he or she will sustain a severe injury in the accident. If the vehicle is moving at 25 mph, that risk increases to 25%, and it is 50% at 33 mph. Any collision is likely to cause at least some injury, though.

  1. Driver awareness

Distraction is a hot topic as government agencies and other groups attempt to raise awareness of the dangers of using an electronic device behind the wheel. A driver who is looking down is more likely to hit a pedestrian without ever touching the brake pedal.

Driver awareness goes beyond distraction, though. Research indicates that the human brain often goes on autopilot while driving and performing other complex tasks to limit the amount of sensory input. The result is that the driver perceives only what he or she expects to see: other vehicles. Pedestrians—and bicycles and motorcycles as well—often do not show up on the radar, resulting in severe and often fatal injuries. Drivers must actively watch for pedestrians.

  1. Vehicle design

In some countries, the design of the front of vehicles as it relates to pedestrian injury is a subject of intense research. The taller the vehicle, the higher on the body the damage will probably be, and the more life-threatening. A pedestrian struck by an SUV will probably sustain much more serious injuries than someone struck by a car. Naturally, a child is at serious risk of injuries or death regardless of the size of the vehicle.