Speed bumps, and speed humps, are raised areas of pavement through parking lots and roads that help regulate speed to ensure the safety of pedestrians and motorists.
The Difference Between a Speed Bump and a Speed Hump
A speed bump is abrupt, having a height between 2-6 inches over a travel length of 6 inches to 3 feet. They are most effective in controlling speeds on low volume, low speed roads, such as private driveways and parking lots, because they cause most vehicles to slow down to about 5 mph or less over the bump.
Speed humps have a more gradual rise and fall of the pavement surface, with a travel length of 12-22 feet long and a height of 3-4 inches. They are designed for residential neighborhoods (including HOAs) so vehicles can go over them at 15-20 mph without causing driver discomfort, and are effective in slowing traffic to 25 to 30 mph between humps in a series.
Benefits of Speed Bumps/Humps
- Slow traffic speeds
- Decrease traffic: Speed bumps may divert traffic to other streets
- Increase safety: slower drivers and less traffic may reduce accident rates
Drawbacks of Speed Bumps/Humps
- Dangerous to bicyclists and motorcyclists
- Increased vehicle emissions because of increased deceleration and acceleration
- Increased response times for emergency vehicles (2-10 seconds per bump/hump)
- Can cause a bump-related jolt injury or damage to vehicles (scraping undercarriage, dislodging exhaust box, damaging suspension, misaligning wheels), which you may be liable for.
Rubber vs Asphalt Speed Bumps/Humps
Asphalt speed bumps/humps are generally preferred to removable speed bumps because they are more solid. They are installed on a permanent basis and require only minimal maintenance. They may chip and/or crumble, but are easier to repair than rubber speed bumps.
Rubber speed bumps are portable and easier to install, but are not as secure or durable. The installation materials can loosen from the vibration of heavy traffic, causing it to separate. They can also be easily removed by people against the speed bump installation. From a maintenance standpoint, speed bumps can deteriorate very quickly, as traffic causes grooves in the rubber or as gaps between the joints form, which can be dangerous to drivers. Markings on rubber speed bumps do not adhere well, and therefore require frequent maintenance.
Design Tips
- You may need a permit if the speed bump will be on a city street or an entryway to a mall or parking lot.
- The height, length and placement of speed bumps should be carefully engineered for safety and liability purposes. The grade of the speed bump should be 8% or less.
- Ensure visibility of the speed bump by placing it near street lighting, using warning signs, painting a warning sign on the road and/or painting the bump with diagonal white or yellow stripes.
- Do not place a speed bump in the middle of a curve in the road, or on areas that slope uphill or downhill.
- Don't put speed bumps in areas reserved for handicapped motorists.
- Do not place speed bumps on high-traffic routes, or routes frequented by emergency vehicles.
- Make sure speed bump placement will not hinder utility access.
- Place them every 200-600 feet, depending on area.