PROGRAMS AND SERVICES
TRAFFIC CALMING PROGRAM
Level 3 Traffic Calming: SPEED HUMPS

A speed hump is a raised pavement section which requires motorists to drive at a reduced speed over an undulation. Speed humps differ from speed bumps (typically used in parking lots) in that humps are typically 3.7 m (12 feet) long as opposed to 0.6 m (2 feet) for speed bumps. The
longer length of the speed hump increases the impact to vehicles at higher speeds and is more comfortable at lower speeds. The typical height of speed humps is 75 mm (approximately 3 inches.)
Speed humps, unlike the other level 3 traffic calming measures, provide only a physical constraint to produce a point speed reduction. While speeds will be reduced at the speed hump, motorists speed beyond the speed hump will are typically found to be unaffected or higher than before. No visual traffic calming benefits are achieved with speed humps.

Due to the jolt created by driving over the speed hump, traffic will be diverted to other adjacent roadways. While this diversion may benefit the roadway with the speed hump, the impact of the diversion to the entire identified neighborhood must be considered. Speed humps installed in areas without curb and gutter improvements may result in motorists driving on private property to avoid the speed hump. Fire trucks and other heavy vehicles are also affected due to the weight of the trucks. In addition, long term, everyday use of the speed hump can cause motorist frustration.

If applied correctly, speed humps can benefit a roadway:

• Reduces motorist speeds at and between speed humps if properly spaced
• Discourages bypass traffic
• Least expensive Level 3 traffic calming measure

Speed humps have several negative impacts. These include the following:

• Unfamiliar or inattentive motorists may lose control of their vehicles
• Increases emergency response times and impacts emergency vehicle equipment
• Undesired diversion of traffic to adjacent residential roadways
• No visual traffic calming effects
• Point speed reduction may have minimal impact beyond the speed hump
• Increased vehicle noise at the speed hump due to braking and acceleration
• Neighborhood aesthetics are affected by speed humps and the associated signing and pavement markings

IMPLEMENTATION

• Impacts motorcyclists and bicyclists
• Define the "neighborhood" to identify potential affected residential roadways. If other roadways will be impacted, concurrence for the installation of the speed hump on the study roadway must be received from two-thirds of the property owners on those impacted roadways.
• Identify primary emergency response routes
• Identify AC Transit service routes
• Roadway section must be straight and flat. In flat areas with adjacent hills, primary consideration must be given to maintaining traffic safety
• Meet warrants for speed hump installation
• Provide street light at each speed hump
• Use the following guidelines for installation of speed humps vs. road humps