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Home > Technical Subjects >Traffic Issues >Speed Humps vs. Speed Bumps

Speed Humps vs. Speed Bumps

In an effort to get drivers to slow down, many towns have considered, or been asked by citizens, to construct speed bumps, or humps, or tables, etc on public roads. If these public roads are townways, then the decision can be made by the municipal officers. If these roads are State Highways or State Aid Highways (inside or outside urban compact areas), then these controls are generally not allowed.

In contemplating this decision, a town must consider several related issues. If the road is planned for reconstruction or it is a new subdivision road, then a "different" design could be done that incorporates traffic calming measures in the geometry so that humps or bumps are not needed.

However, if the road exists today and people are looking to the town to slow drivers down, then the municipality has a few options.

  • First, you need to step up enforcement of current ordinances and speed limits (officially lowering the speed limit or erecting unwarranted STOP signs is not the right approach).
  • Second, the same geometric design options exist which could mean obtaining right-of-way and spending some significant dollars to reconfigure the road.
  • Third, the cheaper option is to construct some speed humps or tables. Do not construct speed B umps which are the shorter, more abrupt obstructions that you see in parking lots and bank driveways and private roads. A speed H ump (or table) is a viable option, if designed correctly, that will slow traffic to a certain level. They usually are 12 to 15 feet long and 4 inches in height. Usually, they are painted to identify a vertical change in the road and there should be advance warning signs from both directions. There are many municipalities across the country which have successfully installed these humps even though they create loads of local controversy. You could choose to install permanent bituminous ones or you could buy portable rubber ones --- there are pros and cons to each type. A town will probably will not find a lot of positive reaction from the folks who have to drive plow trucks, or ambulances, or fire trucks over them.

From the legal perspective, it's important to pass a "traffic ordinance". As stated in State law 30-A MRSA Section 3009, "the municipal officers have exclusive authority to enact all traffic ordinances in the municipality.". Therefore, the Board of Selectmen (or Town Council) can authorize the use of these traffic control devices. From a liability perspective, anyone will sue for anything and a speed hump could be viewed as a "highway defect".

However, State law 23 MRSA Section 3651(1) states that "legal objects are not defects. Trees, structures and other things which exist in accordance with municipal ordinances are not defects in a public way". It may also be difficult to prove that they are dangerous especially when they have been used successfully by some many entities in the US and in foreign countries. If the Town decides to start allowing these humps, I would want to make sure that they are properly designed and marked and signed according to the standards in the MUTCD.

It's important to consider all the ramifications before you decide to open this "can of worms". Once you install one hump, many other folks will want them on their road.


Speed Humps

  • Are a gradual raised area in the pavement surface extending across the entire travel width
  • Typically, 3 to 4 inches in height with a travel length of 12 to 15 ft
  • Have evolved from extensive research & testing
  • Create a gentle vehicle rocking motion which results in most vehicles slowing to 15 mph at each hump and 25 to 30 mph between properly spaced humps in a system
  • Need to be designed and installed with proper planning and engineering
  • Effective at controlling speeds without creating accidents or imposing unreasonable or unacceptable safety risks

Examples of Speed Humps

This is a Speed Hump This is a picture of a speed hump




Speed Bumps

  • Are an abrupt raised area in the pavement surface
  • Effective at controlling speeds on low volume, low speed roads, especially private driveways and parking lots
  • Typically, 3 to 6 inches in height with a travel length of 6 in. to 3 ft
  • Cause significant driver discomfort at typical residential speeds\
  • Cause vehicles to slow to 5 mph or less at the bump
  • Maintenance headaches especially for plow trucks

Examples of Speed Bumps

This is a picture of a speed bump This is a picture of a speed bump



Traffic Calming Information

Much more information can be found on "traffic calming" at the following links:


This page last updated on 1/9/13