TDM Toolbox

Mitigation Calculator

Subsector: Neighborhood Design
Road Diets and Traffic Calming Measures
VMT Reduction Potential: 2
Cost: 2
ROI: 2
StanCOG Relevancy: 4
Land Use Content: Urban, Suburban, Rural
Trip Type: School, Residential, Commute, Recreation
Scale: Community
Timing: Short Term (1-3 years)
Implementors-Private: Developers (Employment), Developers (Residential)
Implementors-Public: Municipalities
References: California Air Pollution Control Officers Association (2024), FHWA Traffic Calming ePrimer, StanCOG Regional Active Transportation Plan, StanCOG Active Transportation Toolkit

Description

Traffic calming measures includes roadway improvements that slow vehicles and enhance safety. There are numerous types of treatments, the more common ones are listed below. Road diets, which reduce the number of vehicle lanes on a roadway to provide more space for landscaping, bicyclists and pedestrians, are also a form of traffic calming.

  • Speed humps, bumps and tables
  • Chicanes, chokers and neckdowns
  • Roundabouts and traffic circles
  • Lane narrowing and/or landscaping
  • Raised intersections
  • Bollards
  • Rumble strips
  • Lane markings and signage
  • Road diets

Implementation Details

  • Install infrastructure such as speed humps, raised crosswalks, curb extensions, and traffic circles in high-collision zones and school areas.
  • Use traffic safety audits and local collision maps to prioritize locations for calming treatments.
  • Coordinate with city public works departments to embed traffic calming into pavement management plans and Safe Routes to School programs.
  • Consider road diets in downtowns and central business districts, where businesses are more likely to attract foot traffic.

Mitigation Potential

Traffic calming measures reduce vehicle volumes and speeds, reducing the level of stress and perceived danger for bicyclist and pedestrians. The increased safety encourages people to walk, bike, and use transit, reducing VMT.

For more details, see CALTRANS VMT Mitigation Program, Road Diets, pg. 39-40 and CAPCOA (2019), Traffic Calming Improvements, pg. 24 for VMT reduction quantification.

Linked Strategies

Equity Considerations

Traffic calming improves safety for pedestrians and cyclists, especially in neighborhoods where residents are more likely to walk or bike. Implementation should prioritize areas with a history of collisions or near schools and parks in environmental justice communities. Inclusive engagement is key to ensuring measures align with local mobility patterns.

Funding Sources

Funding can include the Active Transportation Program, Highway Safety Improvement Program, Surface Transportation Block Grant Program, Congestion Mitigation and Air Quality funding, Safe Streets and Roads for All, and local transportation sales tax revenues. StanCOG’s current programming includes active transportation projects incorporating pedestrian safety, bicycle facilities, traffic-calming features, and street lighting.

Examples/Case Studies

City of Modesto – Neighborhood Traffic Calming Program (NTCP)

The City of Modesto has developed a Neighborhood Traffic Calming Program (NTCP) aimed at improving safety and enhancing the quality of life for residents. The program focuses on mitigating the effects of speeding vehicles, cut-through traffic, and reckless driving in residential neighborhoods. It is funded by Measure L Local Control Traffic Management funds.

City of Ceres – Central Avenue and Hackett Road Pedestrian Safety Corridor

The project includes sidewalk infill, Class II bicycle lanes, curb-ramp improvements, bulb-outs, traffic-speed radar signs, and safety street lighting. The project demonstrates how multiple traffic-calming and pedestrian-safety treatments can be combined within a single Stanislaus County corridor.