Cities like Leawood and Prairie Village have recently addressed speeding in neighborhoods through traffic calming measures. But which measures work the best to slow down traffic?
Speed humps or roundabouts are just two examples of traffic calming measures used in specific areas to slow down vehicle speeds. In several Johnson County cities, these measures are installed on a case-by-case basis due to specific needs on specific roads, city staff members told the Post.
“Traffic calming devices are so site specific that it is difficult to say one type outperforms other types,” Lenexa City Engineer Tim Green told the Post.
Most Johnson County cities use some type of traffic calming measure, but some like Lenexa and Shawnee opt against using speed humps and speed tables in particular.
Here’s a look at how some Johnson County cities attempt to minimize speeding on public streets, and how they determine which type of measure to use.
How do cities decide on a traffic calming measure?
Some cities like Fairway, Leawood, Overland Park and Prairie Village have a traffic calming policy that provides guidance on when and where to use certain measures.
Traffic calming policies allow residents who are concerned about speeding to request a traffic study on their street.
If the study shows a need for traffic calming measures, then the policy normally outlines how to proceed with neighbor approvals, selection of a traffic calming measure and installation.
Traffic calming policies also address how to evaluate traffic calming measures’ effectiveness. For example, Leawood’s policy calls for data collection six months after a traffic calming project is completed and for that data to be compared to the “before” data.
The city of Mission hopes to establish its own traffic calming policy as well, city staff told the Post.
What’s the difference between speed bumps, humps and tables?
The goal of speed bumps, humps and tables is the same: Slow down traffic speeds in specific areas.
“The underlying difference between these calming measures is related to the abruptness of the driver’s experience,” said Brian Scovill, the city engineer with the city of Leawood. He added that “a speed bump is the most severe.”
Green said that in general, speed bumps are used in parking lots or other areas “where very low speeds are necessary.”
Speed humps can work well on residential streets where speed needs to be controlled, Green said. A speed table is ideal for urban areas that prioritize pedestrian safety because it can work as a traffic calming measure and a crosswalk, he said.
Here’s a more in-depth look at the differences between each traffic calming measure, as told by Green:
- Speed bump: A taller, narrower option, typically three to six inches high and 12 inches wide). Often requires a near complete stop to drive over, and are primarily used in parking lots to dramatically slow down traffic.
- Speed hump: A shorter, wider measure, typically 2 to 4 inches high and 10 to 14 feet wide. These are found on residential streets and are more suitable for through-traffic because vehicles can slowly drive over a speed hump without coming to a complete or near complete stop.
- Speed table: The widest measure, typically 3 to 4 inches high and about 22-feet wide. These are used in more urban areas and are typically a more flat surface that can also operate as a crosswalk.
Which cities use speed bumps, humps or tables?
Some cities like Fairway, Leawood, Overland Park and Prairie Village use speed humps or tables in neighborhoods to slow down traffic.
In these cases, cities use traffic studies and compare the results to traffic calming policies to ensure speed humps or tables are justified.
In Mission, there is a speed table encompassing the entire Johnson Drive and Woodson Road intersection downtown.
Stephanie Boyce, the Mission public works director, said the city believes the speed table in downtown “effectively slows traffic in that area.” Boyce said this is based partially on anecdotal evidence.
There are no public speed humps, bumps or tables in the cities of Lenexa, Olathe, Shawnee or Westwood, city staff members told the Post.
Green told the Post that Lenexa opts against speed humps because they can delay emergency vehicle traffic, increase noise and divert traffic to other neighborhoods.
Merriam is the only city the Post spoke with that noted public speed bumps, which are located in the parking structure at the co-located community center and library.
What other traffic calming measures are used in JoCo?
There are a variety of traffic calming measures outlined in city policies that can be used throughout the county, including roundabouts, chokers, raised crosswalks or intersections, textured pavement and median barriers.
While Mission uses one speed table, Boyce said, the city also uses speed feedback signs in various locations to show drivers their actual speed or send messages to slow down. Leawood also uses speed feedback signs throughout the city, Scovill said.
Overland Park uses roundabouts and chokers, which make a street more narrow in a specific spot by bringing both curbs in, according to the Department of Transportation.
Prairie Village uses speed display signs or center islands along emergency routes, where speed tables are unacceptable, Bredehoeft said.
In Roeland Park, drivers may notice pedestrian crossing signs near crosswalks and even a rectangular rapid flashing beacon near Roesland Elementary. The flashing beacon is used to call attention to the crosswalk.
Shawnee uses flashing signs to warn drivers about upcoming crosswalks or stop signs, and collects data to target speed enforcement from the police department, city staff told the Post.
In Westwood, some traffic calming measures include a median island and a road diet along 47th Street, City Administrator Leslie Herring told the Post.
What’s the most effective traffic calming measure?
Based on studies, Fairway found speed humps successfully reduced speeds on Belinder Avenue and Neosho Lane without displacing traffic, City Administrator Nathan Nogelmeier said.
It’s unclear what type of measure is most effective in Fairway as speed humps are the only “engineered” solutions in the city, Nogelmeier said.
In other cities, effectiveness of a traffic calming measure depends on the particular roadway.
Scovill told the Post that “the effectiveness of traffic calming measures varies on a case-by-case basis.”
Still, Scovill said options like speed tables and others that include a “vertical deflection” are considered “widely accepted” at slowing down drivers.
This is evidenced in data Leawood collected before and after installing speed tables along 132nd Street, Scovill said. Data showed that after installing the speed tables, 85% of drivers are traveling by at least a 10-mph reduction in speed.
In Lenexa, there are few before and after studies for traffic calming measures, Green said.
Merriam installs traffic calming devices on a case-by-case basis, city staff told the Post.
Mission city staff told the Post that there is no formal system in place to measure the effectiveness of a speed table.
Meg Ralph, director of communications for the city of Overland Park, said the traffic calming measures the city currently uses like speed humps and roundabouts are the most effective based on data collected. The data includes resident feedback and speed studies, she said.
In Prairie Village, speed tables are the preferred and most successful measure, Public Works Director Keith Bredehoeft told the Post. This is based on resident feedback, but also “after” studies that support some reduction in speeds, he said.
Soon, the city of Roeland Park is installing a combination of speed humps and speed tables along Buena Vista Street between Elledge Drive and 53rd Street. This allows the city to evaluate the effectiveness of humps versus tables, Public Works Director Donnie Scharff said.
Scharff said the city collected data during a traffic study along Buena Vista and plans to collect more after the traffic calming devices are installed to see how well they work.
There is no data collection in Shawnee due to a lack of traffic calming devices like speed humps or tables, city staff said.
