Traffic Calming Examples
Traffic calming is a collection of tools or techniques engineers can use to encourage cars to drive slowly and make it safer for walking and biking. These are proven to be highly effective because they require physical changes to a street to make it safer. Unfortunately, there is no standard formula for applying traffic calming. Measures employed in neighborhoods depend entirely on staff expertise, the available budget, local conditions, and the input received by residents like YOU. Knowing a little about these tools can help you advocate for positive changes to your streets and your community. Read below for information or go to our Resource page for additional links.
Buffer or Planting Strip
Description: An area that separates sidewalks from moving vehicles on the road.
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Physically separates walking area from moving cars.
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Makes walking feel safer and more comfortable.
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Provides space for utilities, trees, grass, or benches.
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May be difficult to provide if street space is limited.
- Tree maintenance may be expensive for the city.
Curb Extension
Description: An extension of the sidewalk into the street that reduces the distance pedestrians must cross.
- Makes pedestrians more visible to drivers
- Reduces vehicle speeds around corners
- Provides area for additional landscaping
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May reduce bike lane width
- City must accept higher cost associated with the improvement
Speed Humps/ Cushions
Description: A longer, less abrupt hump than a typical speed bump.
- Longer than a speed bump and less aggressive.
- Works well when many are used at once.
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Less likely to damage vehicles, but still requires low speed.
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Causes emergency vehicles to slow significantly or stop.
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Could be noisy.
Raised Crosswalks/ Raised Intersections
Description: Slightly raised rectangular area that stretches across the width of the road and long enough for both wheels of a car to be on top at once.
- Provides a good crossing point for pedestrians.
- Bicyclists do not have to move out of way to cross.
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Causes emergency vehicles to slow significantly or stop.
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Could be noisy.
Raised Medians and Crossing Islands
Description: Provide a crossing point to help pedestrians cross multiple travel lanes.
- Have been proven to reduce pedestrian crashes 40%.
- Help drivers know to expect crossing pedestrians.
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No horizontal or vertical deflection means that speed reduction is small and limited to only a few drivers.
Road Diet
Description: Reduction of the number and width of vehicle travel lanes to allow for the addition of bike lanes, sidewalks or parking.
- Decreases pedestrian crashes 29%.
- Encourages narrower travel lanes to slow vehicle speeds.
- Minimal cost in comparison with other treatments.
- Provides new space for medians, bike lanes, sidewalks and/or landscaping.
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May be difficult to provide if street space is limited.
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Tree maintenance may be expensive for city.
Roundabout
Description: Raised circular island in high-volume intesrections that requires traffic to circulate counter-clockwise.
- Reduces vehicle speed.
- Makes crossing safer for pedesetrians and bicyclists.
- Does not require electricity like traffic signals.
- Provides area for additional landscaping.
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Drivers may not be familiar with treatment.
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City may be hesitant to install because of perceived increased difficulty to use for emergency vehicles.
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Note, however, that roundabouts have been designed successfully for emergency vehicles to use.
Traffic Circle
Description: Raised circle in low-volume intersections. Especially good in neighborhoods where large vehicle traffic is not a major concern but speeds, volumes, and safety are problems.
- Very effective in moderating speeds and improving safety.
- Placed at an intersection, can calm two streets at once.
- Attractive if landscaped.
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Difficult for large vehicles to navigate.
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Drivers may not be familiar with treatment.
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May require elimination of some on-street parking.
Diagonal or Back-In Parking
Description: Parking provided at an angle rather than standard parallel parking.
- Slows speeds as drivers anticipate parked vehicles to back out.
- Provides a buffer between sidewalks and traffic.
- Improves safety for cyclists as pulling out of parking space can clearly see cyclist.
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May not be possible due to limited street width.
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When combined with parallel parking, bicyclists are less visible to drivers backing up.
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Back-in parking requires drivers to become comfortable backing into parking spaces.
Popular Fixes to Avoid
One lesson learned from communities with traffic calming experience is to avoid popular solutions that either don't work or cause other problems. These only skim the surface of the real speeding issue. If city staff offers one of these solutions without other tools, ask if additional traffic calming tools would be feasible.
Stop Signs - By law, the purpose of a stop sign is to assign right of way, not to slow vehicles. They are a very limited resource for traffic calming as drivers tend to speed up between stops and roll through stops to make up lost time.
Radar Trailers - Mobile signs flashing the speed of a passing motorist can provide important information to drivers but do not effectively slow traffic.
Speed Bumps - Speed bumps generally do slow traffic. However, most residents WalkSanDiego has talked with consider them unattractive, uncomfortable, and noisy. Emergency responders complain they slow response and damage equipment.
Speed Limit Signs - Experience shows signs of all kinds have little impact on speeding. Physical road changes outlined as traffic calming tools have proven to be far more effective to slow speeds.
