Speed "bumps" are a traffic calming measure commonly seen in parking lots or on private streets. They are not the same as speed "humps" which municipalities use to cut vehicle speed on public streets. If you're thinking of installing speed bumps on private property, there are some regulations you have to follow. Where speed bumps fall below code, you may be legally liable for any vehicle damage that occurs as a result.
TL;DR (Too Long; Didn't Read)
Each municipality has its own technical requirements for speed bumps, and many block their installation altogether.
Can You Install Speed Bumps?
The short answer is, it depends where you live. Some states prohibit you from installing speed bumps on private roads entirely, on the basis that they interfere with emergency vehicles and shift the traffic problem to another street. Others, among them Florida, let you install "reasonable" speed bumps to regulate traffic speed as long as the speed bump does not interfere with easement holders' right of passage. Even then, the county may need to approve the speed bump. Call the local clerk's office and ask what's permitted in your area. You may need signatures from a high number – around 70 percent – of homeowners in the private community before the county will approve the scheme.
Technical Requirements for the Road
While each county has different rules, those that permit the installation of speed bumps typically restrict where you can lay the bumps. In New Hanover County in North Carolina, for example, the road must be light use, carrying no more than 4,000 vehicles per day. At least 15 percent of traffic using the road must exceed 30 mph. You likely will need a traffic survey to determine the road's eligibility for speed bumps, showing such things as the average daily traffic, speed, speed-related collisions and proximity to schools and other places where children could be present.
Technical Requirements for the Bumps
The Department of Transport has prepared a series of national requirements for speed "humps" installed on public roads. There are no such national requirements for private speed "bumps," which means there are no consistent design parameters between installations. You'll see private speed bumps ranging anywhere from 3 to 6 inches in height, with a travel length of 1 to 3 feet – these are the sorts of requirements a county might impose. Some municipalities may have their own technical requirements but generally, these will be assessed on a case-by-case basis based on the road and the traffic. Some things the municipality will look at when considering your application include:
- The necessity for the speed bumps
- An appropriate height for the speed bumps
- The spacing between them
- Their effect on vehicles and traffic flow
- Markings and warning signs to alert drivers to a bump.
As a minimum, you typically need yellow "speed bumps ahead" roadside signage warning drivers of speed bumps in the road and/or the word "BUMP" painted onto the road. However, when seeking permission for speed bumps, the city may ask you to commission a proper engineering study regarding their design and placement. If permission is granted, you'll need to follow instructions for height restrictions, road markings and signs.
Beware of Potential Legal Liability
Take care when installing speed bumps in a private community. A Homeowner's Association has no authority over public roads maintained by the Department of Transport and cannot install speed bumps on these roads, even if speed bumps are favored by residents of the subdivision. There's more discretion where the roads are private, but if the speed bumps represent a material alteration to the common area, installing the speed bumps likely will require a membership vote. Finally, anyone installing speed bumps must do so to the required municipal standard. If you fall short of this standard, a civil court may decide that you are negligent, and you could be liable for any damage suffered by vehicles using the bumps.