Planners and Architects

Create Slow Zones

Slow zones consist of engineered traffic-calming measures such as speed humps, roundabouts, curb extensions, signs, optimized signal timing, and street markings to slow vehicles down to 20 miles per hour (mph) within clearly defined areas.

Guidance
  • Begin by building support among a diverse set of stakeholders
  • Consult with all relevant stakeholders, including emergency services, police, local residents, transportation and public-health professionals, and driver organizations throughout all project stages
  • Create a public-involvement process to incorporate residents’ input on the type and location of proposed traffic-calming measures
  • Establish a 20 mph speed limit across a district and not just an individual road
  • Each zone entrance should have signs showing clearly that drivers are entering a reduced speed zone
  • Install appropriately designed traffic measures at regular intervals about 200’ apart
  • Coordinate signal timing to move vehicles in a slow, steady pace
  • Install traffic-calming measures systematically, such as:
    • Vertical measures: raised intersections, speed tables, speed humps
    • Horizontal measures: curb extensions, chicanes, and realigned intersections
    • Road narrowing: gateways, curb extensions, reduced pavement or lane width, and intersection narrowing
  • Accompany traffic-calming measures with plantings or street furniture to distinguish the roadway treatments, create a more walkable area, and encourage lower speeds
  • Incorporate Public Rights-of-Way-Accessibility Guidelines (PROWAG) to ensure universal access in traffic-calming treatments
  • Create a public-service education campaign to reduce vehicle speeds
  • Measure crash data and vehicle speeds before and after implementation to demonstrate the benefits of speed zones
Benefits
  • Slows vehicular traffic
  • Reduces casualties and collisions substantially (e.g., 42% in London)
  • Reduces number of casualties and collisions on adjacent streets
  • Reduces severity of traffic injuries
  • Reduces cut-through traffic
  • Encourages walking and cycling by creating a safer, more welcoming streetscape
  • Potentially adds greenery and amenities to the streetscape
  • Improves safety for all street users, regardless of age or ability
Considerations
  • Access for commercial deliveries
  • Access for emergency vehicles
  • Access for those with mobility or vision disabilities
  • Access for transit
  • Potential loss of curbside parking
Where to Use It
Professional Consensus

Recommended by the Centers for Disease Control and Prevention

The AASHTO Guide for the Planning, Design and Operation of Pedestrian Facilities includes Reduced Speed Zones, but only within the context of Chapter 2.5.4 Chapter Traffic Control and Crossings Near Schools

Examples

This material is the product of a partnership between America Walks and Sam Schwartz Engineering. Visit here for more information on the partnership.