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Use of Decision Assistance Curves in Advanced Warrant Analysis for Indirect Left-Turn Intersections
Transportation Research Record
  • Sunil Gyawali, University of Nebraska-Lincoln
  • Anuj Sharma, Iowa State University
  • Aemal J. Khattak, University of Nebraska-Lincoln
  • Edward Smaglik, Northern Arizona University
Document Type
Publication Version
Accepted Manuscript
Publication Date

This paper develops decision assistance curves (DAC) to compare delay-based performance measures for three indirect left turn (ILT) intersections, namely median U-turn (MUT), continuous flow intersection (CFI), and jughandle, relative to a conventional signalized intersection. The DACs consist of two graphical tools: (i) DAC-classifier and (ii) two sets of DAC-contours. DAC-classifier plots are used to select the intersection type that produces the minimum system average delay for a specified main and cross-street volume configuration. DAC-contour plots are used to estimate the system average delay difference between a chosen ILT and a conventional signalized intersection as well as to estimate the increase in average delay as compared to a conventional signalized intersection for the most negatively impacted movement. These tools can be used by planners, engineers, or other decision makers to visually identify the intersection type that provides the least average system delay under given volume conditions as well as estimated tradeoffs for choosing a specific intersection type. It was found that the conventional signalized intersection, with protected left turns, was never optimal under studied scenarios. This implies that, for all the studied conditions, there exists at least one ILT or permitted left turn alternative that produces lower delay than the conventional signalized intersection.


This is a manuscript of an article from Transportation Research Record 2486 (2015): 54, doi: 10.3141/2486-07. Posted with permission.

Copyright Owner
National Academy of Sciences
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Citation Information
Sunil Gyawali, Anuj Sharma, Aemal J. Khattak and Edward Smaglik. "Use of Decision Assistance Curves in Advanced Warrant Analysis for Indirect Left-Turn Intersections" Transportation Research Record Vol. 2486 (2015) p. 54 - 63
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