Another example is the introduction of the air fence. The air fence performs a function similar to the air bag in a commercial passenger vehicle, except that rather than inflating upon impact, it is pre-inflated. By acting as a softer, energy-absorbing barrier, air fences can be placed over hard obstacles around tracks that racers might encounter in the course of an accident. With an air fence in place the racer has a much better chance of sustaining fewer injuries than if he were to simply hit the object without any buffer. They are especially important (and more widely used) in motorcycle road racing.