Left-Turn Accommodations at Unsignalized Intersections



The decision to install a left-turn accommodation is a complex one as state and local transportation agencies weigh the left-turn demand, the cost of the accommodation, and the anticipated operational and safety benefits. Clear and consistent application of left-turn accommodations is important for mitigating the impacts of left turns, both for reconstruction projects and for the permitting of new access points.

This report presents guidance for the selection and design of left-turn accommodations at unsignalized intersections. Eleven case studies of typical situations illustrate the use of the guidance. These examples are based on actual locations where left-turn treatments were considered, evaluated, and/or installed. Two of the examples involve analysis of a proposed development.

The contractor’s final report providing background information for the project is as NCHRP Web-Only Document 193. In addition to describing the work that was done, Appendix F presents a legal review of the impact of essential nexus and rough proportionality on development considerations.

Source Organization Location

Washington, DC

Operations Area of Practice

  • Roadway Geometric Design
  • Standards and Specifications

Organizational Capability Element

  • Evaluation of Operations Strategies
  • Roadway Geometric Design

Content Type

  • Research

Role in Organization

  • Associate Engineer
  • Engineer
  • Researcher/Academic
  • Senior Engineer

Publishing Organization


Project Website

Left-Turn Accommodations at Unsignalized Intersections

Prime Contractor
Texas A&M Transportation Institute
Kay Fitzpatrick, Marcus A. Brewer, William I.Eisele et al.
Issue Date
November 1st, 2010
Publication Number
NCHRP Report 745 / NCHRP Web-Only Document 193
ISBN Number
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