Speed Humps, Raised Crossings, and Similar Raised Areas

Purpose

Reduce vehicle speeds, increase driver yielding, and improve bicyclist and pedestrian crossing safety.

Description

A family of vertical traffic calming devices that involve raising the height of the pavement for a short section to slow vehicle traffic and improve safety conditions. Variations include:

Speed humps/tables are raised pavement area with a flat top to limit disturbances to larger vehicles such as emergency response or transit vehicles. Large yield triangles are marked on the sloped areas to provide a visual warning for users.
Tactical speed humps are pre-fabricated speed hump/table devices that are drilled into the pavement to provide a consistent, pre-marked temporary speed hump/table.
Raised crossings are designed in a similar manner to speed humps/tables but provide a crossing along wider flat tops. The crossings can be either at sidewalk level or modified to be 3 to 5 inches high to address drainage challenges.
Speed cushions have wheel cutouts to allow large vehicles such as buses or emergency vehicles to pass through unaffected. Unlike speed humps, speed cushions can’t be used in combination with crosswalks.
Raised intersections are when the entire intersection is elevated to the level of the sidewalk to reduce speeds for cars approaching the cross streets and pedestrian crossings – applicable at minor intersections.

Safety Benefits

May reduce vehicle speeds and improve driver yielding to crossing pedestrians.
May increase the height of pedestrians in driver’s field of vision.
Raised crossings may provide a continuous travel path for pedestrians with disabilities. Detectable warning surfaces (e.g., truncated domes) must always be implemented at pedestrian crossings, per ADA standards, to provide access for people with vision disabilities.
May reduce the frequency and severity of crashes for all road users.
Studies in Arlington showed about a 26% decrease in average speeds when tactical speed humps were applied.

Street Types and Context

Applicable Street Types

All local streets.

Other Location Guidance

Vertical traffic control measures such as speed humps, tables, and cushions are best used on streets with lower vehicle speeds (25 mph and under) and volumes where traffic calming is needed, such as near pedestrian and bicycle activity generators (i.e., schools, parks, trail crossings).

Primary User Groups

All users: pedestrians, bicyclists, scooters, cars, buses, motorcycles, large trucks/vehicles.

Key Implementation Considerations

Consider priority and delay of emergency response vehicles, buses, or heavy vehicles.
Certain designs require modifications to existing drainage.
Investigate feasibility of other traffic calming measures first.

Expected Crash Reduction

For raised crossings:

45% for pedestrian crashes (Elvik et al. 2004).
51% for bicycle- vehicle crashes on entrances or exits to streets and driveways (Schepers et al. 2011).

A definitive crash reduction estimate has not been established for speed humps/tables/cushions. Research suggests speed humps, tables, and cushions reduce crash severity (Elvik and Vaa, 2004).

When piloted in Arlington in 2023 and 2024, tactical speed hump devices reduced speeding (cars driving 20mph+) in school slow zones by about 43%.

Cost

Costs are typically in the moderate range

Timeline

Watch a quarter full and another watch halfway full.

Less than one to three years depending on complexity and engagement. Raised crossings implemented with changes to drainage may take longer.

Applications in Arlington

Visit Vision Zero Program Dashboard: Raised Traffic Calming to see where this tool has been implemented.

Vision Zero Dashboard

Safety Pilot Project

Arlington County has installed two rounds of tactical speed humps in school zones across the County as part of a safety pilot project. The installation of speed humps reduced both average and 85^th percentile speeds along all project corridors, by 33.7% and 32.7% respectively during Round 2.

References