Types of Traffic Calming Treatments

How do we approach traffic calming design?

Traffic calming projects are designed using speed data, crash history, street features, and nearby land uses. The goal is to reduce speeding, improve safety, and make streets more comfortable for everyone walking, biking, rolling, and driving. These improvements also help reduce the chance of serious crashes.

Where Traffic Calming Devices Are Placed
Traffic calming devices are usually placed about 350–700 feet apart along a street. Streets with higher speeding concerns may need devices placed closer together to help keep speeds lower. Spacing devices throughout a street helps slow traffic along the entire area instead of just one spot.

Focus on Areas with More People Walking and Biking
Traffic calming is often prioritized near places with more pedestrian activity, such as parks, schools, transit stops, greenway crossings, and community destinations. These areas benefit from slower speeds to create safer and more comfortable spaces for people walking, biking, and rolling.

Using Crash History to Improve Safety
Crash data is reviewed when designing traffic calming projects. If crashes are linked to speeding at a certain location, traffic calming devices may be placed there to help improve safety.

Designing the Right Solution for Each Street
Every street is different and is reviewed to determine the best traffic calming approach. Designs are based on engineering practices, traffic guidelines, field reviews, and community feedback.

Street Width and Traffic Volume Matter
Some traffic calming devices, such as traffic circles, chicanes, and chokers, need enough space to work properly. On narrow streets, these tools may not change driver behavior because vehicles can pass through without slowing much. In these cases, speed humps or speed cushions may work better.

Traffic calming devices that narrow or shift the roadway work best on streets with moderate to higher traffic volumes, where drivers are more likely to slow down. On streets with less traffic, drivers may be able to pass through these features without much change in speed. In these situations, speed humps or speed cushions are often more effective at creating consistent speed reductions.

Speed Humps (Vertical Treatment)

Speed humps are one of the most effective ways to slow down traffic. They are quick to install, cost less than many other traffic calming devices, and their small size makes them easy to place in different locations along a street. However, they can make the ride less comfortable for drivers, may cause small delays for emergency vehicles, and can increase vehicle noise as drivers slow down and speed up.

Speed Cushions (Vertical Treatment)

Speed cushions slow drivers down much like speed humps, but their wheel-gap design lets many emergency vehicles pass with little to no delay. People riding bikes can usually cross them with little impact, and their smaller size makes them easier to install in different locations. However, they cost more and take longer to install than speed humps, can make the ride less comfortable for drivers, and may still cause small delays for some emergency vehicles.

Speed Table (Vertical Treatment)

picture of speed table treatment in the road

Speed tables help reduce speeds on streets with higher speed limits, such as 30 mph roadways. Their longer design creates a smoother ride for drivers compared to traditional speed humps. However, their larger size can make them harder to place in some locations and may cause small delays for emergency vehicles.

Neighborhood Traffic Circle (Horizontal Treatment)

picture of a neighborhood traffic circle

These intersection improvements help slow vehicles as they enter and travel through intersections, which can reduce the chance and severity of some crashes. They also improve pedestrian safety by lowering vehicle turning speeds and usually have little impact on emergency response times. However, construction can be more disruptive than other traffic calming options, and these treatments require enough space to work properly, making them unsuitable for some locations.

Split/Pinch Intersection (Horizontal Treatment)

image of a split pinch intersection in a neighborhood

Split/pinch intersections slow vehicles by narrowing the roadway and guiding drivers through the intersection. They can make it safer for people walking by shortening crossing distances and making them easier for drivers to see. They have little effect on emergency response times and can be paired with other safety improvements. However, they may require more construction than some other traffic calming options, need enough space to install, and may not work as well on streets with less traffic.

Lane Narrowing (Horizontal Treatment)

picture of a narrow lane street treatment

Lane narrowing helps slow traffic by making the road feel smaller, which encourages drivers to slow down. It can also create space for bike lanes, sidewalks, safety areas, or parking. It can be especially helpful on streets without sidewalks by creating more space between people walking and vehicles. Lane narrowing has little impact on emergency vehicles. However, it may not slow traffic as much as other traffic calming tools and may require new road markings. How well it works depends on the size and layout of the street.

No single traffic calming device is appropriate for every street. Device selection is based on roadway width, traffic volumes, operating speeds, crash history, and surrounding land uses.

Contact

ntmp@raleighnc.gov

Department:: Transportation

Service Categories:: Mobility Strategy and Infrastructure

Was this page helpful?

Yes

Please choose the type of issue you are experiencing with the page from the dropdown.

Comments

Would you like to be notified by the City about your feedback?

This feedback widget is not intended for customer service issues.

This feedback is reviewed monthly to help us improve our site. For immediate customer service please refer to our staff directory.