The National Academies

NCHRP 03-98 [Final]

Guidelines on the Use of Auxiliary Through Lanes at Signalized Intersections

  Project Data
Funds: $400,000
Research Agency: Kittelson & Associates
Principal Investigator: Brandon Nevers
Effective Date: 2/27/2009
Completion Date: 8/30/2011
Comments: Final Report published as NCHRP Report 707

Auxiliary through lanes (ATLs) at signalized intersections have been used throughout the United States. An ATL is a limited-length through lane added upstream and downstream of an intersection. Prior studies suggest that the length of auxiliary lanes beyond the intersection is a significant factor affecting upstream lane usage and, therefore, the intersection capacity. However, the conditions for their effective use and their affect on operations, safety, and the site location were yet to be documented. This research provides a technical assessment for their use, documents their affect on operations and safety, and provides guidelines including design criteria and placement. 

The guidelines, published as NCHRP Report 707, are available hereThe guidelines document aims to assist transportation professionals in the effective and safe use of intersection auxiliary through lanes. The guidelines are accompanied by a final report posted on the TRB website as NCHRP Web-Only Document 178: Assessment of Auxiliary Through Lanes at Signalized Intersections (available here) along with a spreadsheet based computational engine posted here.



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