In the event emergency exits are required, the crash bar works efficiently to allow people to pass through security doors without a reduction in speed. A crash bar's fast-acting mechanism reduces the risk that a rushing crowd might suddenly become a logjam at the exits. Such a human stampede, which has many historical precedents, can cause falls, crushing, and other injury because the rear of a crowd has no idea that the people at the front of a crowd have come across a door.