Document Type

Thesis

Date of Award

10-2024

School/College

College of Science, Engineering, and Technology (COSET)

Degree Name

MS in Transportation Planning & Management

Committee Chairperson

Yi Qi

Committee Member 1

Mehdi Azimi

Committee Member 2

Fengxiang Qiao

Committee Member 3

Xuemin Chen

Keywords

Diamond Interchange, Maximum Bandwidth, Time Space Diagram, Traffic Signal, Signal Timing Sequence

Abstract

Interchange is an important element to accommodate the critical movement between arterials and freeways. To operate efficiently, innovative interchange designs have been suggested by transportation professionals. Recently, an innovative interchange design called flipped left diamond interchange (FLDI) design has been proposed. That aims to increase capacity and improve efficiency by flipping the left-turn lanes in opposing directions, eliminating conflicts between opposing left-turn movements. So, the signal timing of the left turn movements and through movements are independent which indicates the signal timing of these movements can be determined based on their volume. Due to this independence, any signal timing sequences could be applied flexibly for interchange operation which may be helpful for better coordination with the adjacent signals compared to conventional interchange design. In that regard, this study aims to find out the operational benefits of FLDI and test different signal timing sequences for the interchange operation. For this purpose, a comprehensive literature review is done and an Excel-based tool has been developed in this study. Findings showed that FLDI is capable of overcoming the challenges of operationally, accessibility issues, frontage road through movement, driver acceptance, and cost of implementation. The results of the Excel tool showed when the FLDI phase sequencing matches with the adjacent signals, the maximum total bandwidth increases significantly. This study expects to enhance the decision-making strategy in implementing FLDI regarding traffic progression and overall operational benefits.

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