A speed hump (also called a road hump, or undulation and speed ramp) is a rounded traffic calming device used to reduce vehicle speed and volume on residential streets. Humps are placed across the road to slow traffic and are often installed in a series of several humps to prevent cars from speeding before and after the hump. Common speed hump shapes are parabolic, circular, and sinusoidal.
Generally, speed humps have a traverse distance of about 3.7 to 4.3 m (12 to 14 ft) and span the width of the road. The height of each hump ranges from 76 to 102 mm (3 to 4 in). The traverse distance and height of each hump determines the speed at which traffic will travel over the devices. Shorter traverse lengths and greater heights slow cars most drastically. When placed in a series 110–170 m (350–550 ft) apart, humps will reduce 85th percentile speeds by 13–16 km/h
Warning signs should be used to notify approaching motorists of upcoming humps. Humps generally have pavement markings to enhance visibility and a taper edge near the curb to allow a gap for drainage.
Speed humps are used in locations where low speeds are desired and suitable for the surrounding traffic environment. Speed humps are typically placed on residential roads and are not used on major roads, bus routes, or primary emergency response routes. Placement is generally mid-block between intersections.