Civil, Construction and Environmental Engineering
Journal or Book Title
Transportation Research Record
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.
Research Focus Area
National Academy of Sciences
Gyawali, Sunil; Sharma, Anuj; Khattak, Aemal J.; and Smaglik, Edward, "Use of Decision Assistance Curves in Advanced Warrant Analysis for Indirect Left-Turn Intersections" (2015). Civil, Construction and Environmental Engineering Publications. 86.