Traffic Calming

Traffic calming incorporates engineering design and management strategies that balance vehicular traffic on streets with other uses. Engineers explore and implement traffic calming techniques that lessen the impact of motor vehicle traffic by slowing it down, or literally "calming" it. The goals of traffic calming projects may include:

  • Enhancing quality of life
  • Creating safe and attractive streets
  • Promoting pedestrian, cycle and transit use
  • Helping to reduce the negative effects of motor vehicles on the environment

These goals are meant to achieve safer roads through slower speeds with fewer accidents. Besides positively influencing the livability of a particular location, traffic calming techniques can be applied inexpensively. When combined with other small-scale improvements, traffic calming projects can immediately enhance a neighborhood or corridor while being tested and refined to meet long-term needs. These strategies may be employed by painting lines, colors and patterns on the road, eliminating or adding parking, or installing sidewalk extensions or similar structures. Regardless of what traffic-calming action is undertaken, the benefit to a community is greater when the technical improvements are strengthened by visual enhancements like trees, flowers and other amenities.

The City of Saint Charles Engineering Department has completed traffic calming projects along Boschertown Road, New Town Boulevard, Elm Street and within the Charlestowne development. The City code even reflects traffic calming. Section 405.150 requires that developers incorporate traffic calming measures within a new development. Example projects include: landscaped curb bump outs which narrow driving lanes, islands, road realignments, signalized crossings to enhance pedestrian safety, streets trees and feedback signs. All of these help create a safe and attractive street for drivers, pedestrians and bicyclists.

To begin the process, a group of citizens representing 10 or more separate households from a given neighborhood (subdivision) submits a letter to Public Works expressing their interest in improving traffic conditions in their neighborhood. The letter should describe, as completely as possible, the location and details of the types of traffic problems perceived. This letter must be sent to the Councilperson representing the ward in which this subdivision/traffic neighborhood is located.

Once the request has been received, the Department of Engineering will schedule a meeting in the neighborhood. At that meeting, Engineering staff will explain available traffic management strategies, as listed in Attachment 2, and listen to opinions about traffic problems from the neighborhood.

Traffic calming devices are separated into three categories: speed reduction, volume reduction and other traffic management strategies.

Traffic Calming Policy (PDF)

Traffic Calming Request (Survey123)

Speed Reduction

  • Traffic Circles - a raised island, placed in intersections, around which traffic circulates. They can be controlled by yield signs, two-way stops, or all-way stops. Circles prevent drivers from speeding through an intersection by impeding the straight through movement.
traffic circle 1
  • Semi-Circle Chicanes - these are typically placed at "T" intersections. In this application, a half circle is placed on the through street opposite the terminating leg of the intersection. Additional half circles are placed on the through street on either side of the terminating leg. Drivers must first turn to the left, then back to the right as they pass through the chicane.
  • Chicane - a series of two or more staggered curb extensions on alternating sides of a roadway. The horizontal deflection causes motorists to reduce speed.
  • Speed Limit Pavement Legends - painting of speed limit legends on the roadway adjacent to speed limit signs.
Pavement Markings
  • Permanently Mounted Driver Feedback Signs - also known as radar speed signs, use speed awareness to slow traffic, ultimately making roadways safer.
  • Raised Intersections - create a safe, slow-speed crossing and public space at minor intersections. Similar to speed tables and other vertical speed control elements, they reinforce slow speeds and encourage motorists to yield to pedestrians at the crosswalk.
raised intersection
  • Center Island Narrowing - are raised islands located along the centerline of a street that narrow the travel lanes at that location. These are sometimes referred to as midblock medians, median slow points, or median chokers.
Center Island Narrowing
  • Choker - are curb extensions that narrow a street by extending the curbs towards the center of the roadway. The remaining street cross-section consists of two narrow lanes.
choker and car
  • Speed Table - are traffic calming devices that raise the entire wheelbase of a vehicle to reduce its traffic speed. Speed tables are longer than speed humps or bumps and have a flattop. Heights with a height of Three to three and a half inches and a length of twenty-two feet. Vehicle operating speeds for streets with speed tables range from twenty-five to forty-five miles per hour,  depending on the spacing.
Speed Table1

Volume Reduction

Full Diverter
  • Full Diverters - a barrier placed diagonally across an intersection blocking the through movement. The barrier blocks the through movement in both directions.
Partial Diverter
  • Partial Diverters - a barrier that blocks one-half of a street. The barrier blocks the through movement in one direction.
  • Closures - generally on residential streets, these prohibit through-traffic movement or prevent undesirable turns. Street closures may be appropriate where large volumes of through-traffic or "short-cut" maneuvers create unsafe conditions in a residential environment.

Other Traffic Management Strategies

  • Selective Traffic Enforcement Patrol - combines intensive enforcement of specific traffic safety laws with extensive communication, education, and outreach informing the public about the enforcement activity.
  • Traffic Safety Trailer - a portable radar trailer that will display the posted speed and a changeable message board with the driver's speed. The trailer will be deployed where applicable given clear sigh distance and vegetation free shoulder. The trailer helps remind drivers what the posted speed limit and that he or she should abide by.
  • Decoy Vehicle - uses unoccupied marked police vehicles to give a perception of being present everywhere.

For more information on traffic calming, contact the City of Saint Charles Department of Engineering at 636-949-3237.