A spee bump (in British English a speed hump, road hump or sleeping policeman) is a velocity-reducing feature of road design to slow traffic or reduce through traffic. A speed bump is a bump in a roadway with heights typically ranging between 3 to 4 inches (7 to 10 cm). The length of speed bumps are typically less than or near to 1 foot (30 cm); whereas speed humps are longer and are typically 10 to 14 feet (3 to 4 m) in length.