A speed bump is a traffic calming feature of road design used to slow traffic, or reduce through traffic, via vertical deflection. They are also known as a sleeping policeman in Jamaica, a kipping cop; in British English a speed hump, road hump (not to be confused with the wider speed hump), speed breaker; in New Zealand English a judder bar; in Hiberno-English a ramp. A speed bump is a bump in a roadway with heights typically ranging between 3 and 4 inches (and cm).