Speed humps are raised areas in the pavement surface that extend across a roadway. Speed humps create a gentle vehicle rocking motion that causes most vehicles to slow to approximately 15 miles per hour (mph) or less at each hump, and approximately 25 mph to 30 mph between properly spaced humps. Speed humps should not be confused with speed bumps that cause discomfort to motorists and a shock to vehicles only at low speeds. The types of speed humps that are typically installed in the City are:
a. Parabolic/Rounded Top Speed Hump – An asphalt hump that is 12’ long and has a nominal height of 3 1/2" at its highest height
b. Flat Top Speed Hump/Table - An asphalt hump that is 22’ long (consisting of a 6’ inclined ramp, a 10” flat raised flat section, and a 6’ declining ramp section) and has nominal height of 4“ at its highest height
c. Speed Cushion - An asphalt hump that is 6.5’ long and 6.75‘ wide, with an incline/ramp of 24” and a nominal height of 3" Cushions are placed along the roadway in pairs with a separation of 24” to accommodate vehicles with a wide wheel axle base (e.g. boat trailers and cyclists).
Neighbor support for the installation of speed humps shall be documented by a City-conducted notification of all properties with addresses on the road and, when appropriate, the surrounding neighborhood.
Neighbor Survey
A notification will be mailed out to neighbors who would be directly impacted by the installation of speed humps on a City roadway to determine their preference for speed humps. The City utility billing address database will be used to determine who will be notified. The neighbors contacted will be able to respond via the City website or by phone. The City will require 60% of neighbors (property owners and/or occupants) responding as minimum support to progress with the speed hump process, which is the same threshold required for utility undergrounding. If the responses do not meet the minimum support threshold, the City will coordinate with proper entities that requested the installation of speed humps.
Engineering Study
Since speed humps may divert traffic to other streets, an estimate of the amount and location of that diversion will be made so that the potential impacts of the proposed humps may be fully considered. If the humps are expected to create equal or greater traffic problems on another residential street, they will either not be installed, or humps will be considered for the other impacted areas.
Street Classification and Use
Speed humps will not be installed on any "collector" roads that carry more than 6,000 vehicles per day and will not be installed on any higher category roads than "collectors." Speed humps will not usually be installed on any cul-de-sacs; however, because of the differing types of land uses found on some cul-de-sacs, the City Commission may consider the installation of speed humps on a case-by-case basis.
Street Width and Number of Lanes
Speed humps will be used only on streets with no more than two travel lanes, or where the overall pavement width is not greater than 40 feet. In addition, the pavement should have good surface and drainage qualities. Speed humps are generally placed in a series of 250 to 500 feet apart, at property lines, to minimize noise.
Street Grades
Speed humps will only be considered for use on streets with grades of eight percent or less approaching the hump. When installed on streets with significant downgrades, special care shall be taken to ensure that vehicles will not approach the humps at excessive speed.
Horizontal and Vertical Curves
Speed humps will not be placed within severe sharp horizontal or vertical curves that might result in substantial lateral or vertical forces on a vehicle traveling over the hump. Humps will be avoided within horizontal curves of less than 300 feet centerline radius and on vertical curves with less than the minimum safe stopping sight distance. If possible, humps will be located on tangent rather than curve sections.
Sight Distance
Speed humps will generally be installed only where the minimum safe stopping sight distance can be provided, as defined by the American Association of State Highway and Transportation Officials in A Policy on Geometric Design of Highways and Streets.
Traffic Speeds
Speed humps will generally be installed only on streets where the posted speed limit is 35 mph or less. Speed humps will be carefully considered on streets where the majority of vehicles travel at relatively fast speeds, such as 45 mph or greater. Installation of speed humps will be considered on roads where the 85th percentile speed (average of both directions) is at least 8 mph above the posted speed limit.
Funding may be extended to include roads that are expected to have traffic diverted to them as a result of speed hump installation.
Traffic Volumes
Rounded profile or flat top speed humps will be considered for installation on streets with an average daily traffic volume of between 450 to 3,000 vehicles per day.
Traffic Safety
Proposed locations will be evaluated to ensure that installing speed humps will not introduce increased accident potential.
Vehicle Mix
Speed humps will not normally be installed on streets that carry significant volumes (greater than five percent) of long wheelbase vehicles or emergency routes unless there is a reasonable alternative route for those vehicles. Special consideration will also be given to motorcycles, bicycles, and other types of special vehicles that use the street. The impacts that speed humps might have on these individual vehicle types will be considered in the decision to install humps and in their design and location.
Transit Routes
Speed humps will not generally be installed along streets with established transit routes.
Schools and Parks
If a street is immediately adjacent to a school or public park, at least 30 percent of the traffic must be traveling at or above the posted speed limit and the 85th Percentile Speed (average of both directions) is at least 6 mph above the posted speed limit.
Emergency Response
If the street is a primary or secondary route for emergency response vehicles, the Fire-Rescue Department will be contacted. If the Fire Rescue Department objects to the installation of speed humps on the street, the City Manager shall make the final decision.
Payment for Speed Hump Installation
Speed humps that meet the criteria will be funded based on available City funding.
Other Considerations
Speed humps may be considered in neighborhoods that have completed a comprehensive planning study such as a Neighborhood Mobility Masterplan. This consideration could be in lieu of meeting the speed and volume thresholds based on Transportation and Mobility’s determination that it does not impact the overall roadway network.