What are the Best Traffic Calming Methods?

Published on August 28, 2024

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Traffic Calming is the combination of mainly physical measures that reduce speeds and improve safety.  These physical changes to the roadway create a “feeling” that causes the driver to slow down. There are many tools in the toolbox for traffic calming.  And just like real tools, some do the job better in some locations than others.  There is a decision-making process that is necessary for choosing the right tool.  There are also specific criteria that municipalities need to follow to assure that safety issues are handled the same throughout the state. The two main documents that are used by all agencies are the MUTCD (Manual on Uniform Traffic Control Devices) and the Florida Greenbook, which is the manual of uniform minimum standards for design construction, and maintenance of streets and highways.  The primary goal is to reduce speed and make the roadway safer for all users. 

How are speed limits determined? 

Most people will drive the speed that they feel comfortable with regardless of posted speed limits.  Lowering the speed limit is not effective in slowing down drivers.  Setting speed much lower than current operating speeds may not achieve desired levels of compliance without other changes to the roadway or to enforcement. It is necessary to change the physical characteristics of the road to make people want to drive slower.  Speeds are usually set based on the type of road and the 85th percentile speed, or the rate which 85% of motorists travel while using the road. That means that out of 100 people 85 are driving at or near the speed limit. 

Traffic Engineering Studies 

When the public reaches out to the City staff with a concern about speeding, a traffic study is initiated.  The traffic study collects speeding data using Jamar Traffic Data Radar.  This system provides an output as shown below.  For this example, we can see that the percentage of people actually speeding was about 6%.  Because of the low rating, no changes were recommended. 

 

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Traffic Calming Tools 

If a traffic study shows that there is a speeding issue, what can the agency do to reduce speeding? Speed enforcement is usually the first method used to reduce speeding.  Enforcement of speed limits is the responsibility of various law enforcement officials and they will be contacted to provide enforcement in an area for a specified time period.  But if enforcement does not reduce speeding, other techniques may be used.  These include speed humps, Traffic Circles, chicanes (modified medians) and narrowing the roadway (narrowing the lanes using pavement markings).  It is important to keep in mind that an agency should not create a new problem by trying to fix an existing one. 

The method most citizens want to go to are the speed humps or speed tables.  However, most agencies no longer install new speed humps.   

  • They are hard to maintain and frequently wear down 

  • They delay first responders.  A few seconds lost navigating a speed bump is a few seconds delay to responding to a fire or a medical emergency. 

  • It moves traffic to the adjacent streets. 

  • If cars drive over speed bumps at average speed, the car can see significant damage, especially the shocks. 

Traffic calming will always be a balancing act between mobility and safety. And there are many factors taken into consideration when reviewing neighborhood traffic concerns to determine the most feasible traffic control measures. These factors include: the surrounding roadway network, resident and emergency vehicle access, speeds and/or volume of traffic, accident or crash history and construction in the nearby area.  Education and enforcement will also be important tools in achieving any reduced speeds. 

For more information or questions on traffic calming, contact Dunedin’s City Engineers at https://www.dunedingov.com/Your-Government/Departments/Utilities-Engineering  

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