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Design Standards for Unobstructed Sight Lines at Left-Turn Lanes

Status:  Complete
Report Date:  09/09/2019

Summary:

Positive offset left-turn lanes are one solution to improving left-turning motorists visibility of opposing through and right-turning traffic. MnDOT is revising its Road Design Manual and seeks to incorporate more information, policies and design guidance regarding positive offset left-turn lanes. Researchers from the University of Wisconsin's Traffic Operations and Safety Laboratory reviewed safety performance data from research that examined left-turn offsets. They also consulted 23 state DOT road design guides to understand the extent of available guidance. Findings from this research effort were used to develop extensive revisions to the Road Design Manual, addressing a wide range of design factors and applications of the positive offset left-turn lane throughout Minnesota's highway system.

Final Deliverables:

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