Left-Turn Hardening and Slow-Turn Wedges

Left-turn hardening refers to the use of striping, surface materials, and vertical delineators at intersections to reduce left-turning speeds and to prevent “corner cutting”.  Common types of left-turn hardening include centerline hardening, where modular curbs or barriers are placed where the centerline meets the intersection, or slow turn wedges, where striping and barriers are placed at corners to slow turning vehicles. This infrastructure is often installed at intersections where a minor street intersects with a major street and is especially useful at intersections with high volumes of pedestrians where speeds of left-turning vehicles are an issue.

A turning car is slowed by a small speed bump at an intersection. 
 A photo of an corner with a slow-turn wedge and left-turn hardening marked by yellow striping and flex posts.
Boston, MA (City of Boston)  New York, NY (NYC DOT) 

 

Program Goals This Project Type Meets

  • Increase safety (speed management)

Typical Applications

  • Centerline hardening is often installed at intersections where a minor street intersects with a major street.
  • Slow turn wedges are often installed at intersections of two one-way streets

Material Options

Design Considerations

  • Maintain truck, bus, and fire truck turning ability and make elements mountable if needed

Other Considerations

  • Opportunity to include artistic elements and/or coordinate with a larger intersection mural project
  • ADA accessibility of the sidewalks, curb ramps, and turn-wedge if intended to serve as a curb extension, particularly for pedestrians with visual impairments

Other Resources

Related Information

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