Authors: Minseok Kim, Hyeonmi Kim, Sungyoon Park and Saed Rahwanji
Conference: presentation at the 2014 TRB Alternative Intersections & Interchanges Symposium.
Unconventional Design: Six types of UIDs, including Superstreet (RCUT), CFI, CGT, DDI, SPUI, and DRI.
Purpose: presents the state of practice, case studies and analysis tools on unconventional designs in Maryland.
The Maryland State Highway Administration (MSHA) has been active in adopting unconventional design concepts at local intersections and interchanges as a feasible solution for relieving arterial congestion and improving safety. This paper presents the state of practice, case studies and analysis tools on unconventional designs in Maryland. The state of the practice focuses on six concepts consisting of restricted crossing u-turn (RCUT) intersection, continuous flow intersection (CFI), continuous green-T (CGT) intersection, diverging diamond interchange (DDI), single point urban interchange (SPUI), and double roundabout interchange (DRI). Case studies summarize the planning and design considerations that have been made for the first signalized RCUT intersection and DDI in the State of Maryland in addition to the 2nd CFI in Maryland. An overview of two analysis tools, developed as a joint research effort between MSHA and the University of Maryland at College Park, is also provided to introduce the Maryland Intersection Design & Capacity Analysis Program (MIDCAP) and Maryland Unconventional Intersection Designs (MUID) Analysis Tool. MIDCAP is useful to conduct capacity and queuing analyses based on the MSHA’s standard critical lane volume (CLV) and queuing methodology. MUID Analysis Tool contains statistical models to estimate the delay and queue in planning evaluations and models to optimize signal timings in operation analysis for three design concepts: 1) CFI, 2) DDI, and 3) signalized RCUT.