How to Design a Speed Bump

Speed bumps calm traffic.

You’ve driven over them and if you’re not paying attention, they’ll catch you by surprise, causing your car to jolt up and down as you pass over. Speed bumps serve the sole purpose of slowing down traffic in areas where dashing motorists might be dangerous to themselves or pedestrians. When you need to design a speed bump, there are a few guidelines to keep in mind. The safety of motorists and pedestrians is tantamount.

Things You'll Need

• Scale map of parking lot or road
• Local traffic code

Instructions

1. Find out your local regulations concerning speed bumps. This may involve getting a permit from your local street authority if the bump is to be on a city street or an entryway to a mall or parking lot. On private property, most communities allow you to install speed bumps, but you may be liable for an injury determined to result from a speed bump-related jolt or for damage to the under-carriage of a vehicle.

2. 

   Design a speed bump with no more than an eight percent grade if it is on a public roadway with a posted speed limit of 25 mph. It is unlikely that you will receive a permit to install a speed bump on a public roadway where traffic may legally exceed 25 mph or on a route designated for truck drivers and school buses. Some communities require an even lower grade.

3. Plan the speed bump for placement before or after a curve in the road but not in the middle of the curve. An unexpected bump while turning may make cause a motorist to lose control of his or her vehicle.

4. Space speed bumps no closer than 300 feet from each other on a public roadway. You may place speed bumps closer together on private property, but you may not create an access hindrance to utilities. For instance, a speed bump in close proximity to a sewer utility must not hinder the parking ability of service vehicles.

5. 

   Encourage motorists to slow down before crossing your speed bump with warning signs at least 100 yards in advance of the bump if posted traffic speeds are between 15 and 25 mph. Install signs, constructed in the traditional diamond hazard shape that read, “Speed Bump.” In addition, consider designing a painted sign on the road just in front of the bump and paint the entire bump bright orange.

6. 

   Consider buying pre-made speed bumps online in four- or six-foot lengths and laying them end to end, if necessary, to create a longer bump. These bumps come ready to install on a roadway or parking lot and feature painted safety strips for easy visibility (see Resources below).

Tips & Warnings

• Your community may have stricter standards on speed bump regulations, so find out before you install one.

• Don't design speed bumps in areas reserved for handicapped motorists.

Resources

• Read this Article in Spanish
• Order pre-made speed bumps.