Title page for ETD etd-08202012-163019


Type of Document Dissertation
Author Adam, Zaeinulabddin Mohamed Ahmed
Author's Email Address zadam@vt.edu
URN etd-08202012-163019
Title Development and Applications of Multi-Objectives Signal Control Strategy during Oversaturated Conditions
Degree PhD
Department Civil Engineering
Advisory Committee
Advisor Name Title
Abbas, Montasir M. Committee Chair
Hobeika, Antoine G. Committee Member
Pasupathy, Raghu Committee Member
Rakha, Hesham Ahmed Committee Member
Keywords
  • Signal system
  • Oversaturation control strategy
  • Critical route
  • Pareto front
  • Queue management
  • Wavelet analysis
  • Multi-objective control
Date of Defense 2012-08-10
Availability unrestricted
Abstract
Managing traffic during oversaturated conditions is a current challenge for practitioners due to the lack of adequate tools that can handle such situations. Unlike under-saturated conditions, operation of traffic signal systems during congestion requires careful consideration and analysis of the underlying causes of the congestion before developing mitigation strategies. The objectives of this research are to provide a practical guidance for practitioners to identify oversaturated scenarios and to develop a multi-objective methodology for selecting and evaluating mitigation strategy/ or combinations of strategies based on a guiding principles. The research focused on traffic control strategies that can be implemented by traffic signal systems. The research did not considered strategies that deals with demand reduction or seek to influence departure time choice, or route choice. The proposed timing methodology starts by detecting network’s critical routes as a necessary step to identify the traffic patterns and potential problematic scenarios. A wide array of control strategies are defined and categorized to address oversaturation problematic scenarios. A timing procedure was then developed using the principles of oversaturation timing in cycle selection, split allocation, offset design, demand overflow, and queue allocation in non-critical links. Three regimes of operation were defined and considered in oversaturation timing: (1) loading, (2) processing, and (3) recovery. The research also provides a closed-form formula for switching control plans during the oversaturation regimes. The selection of optimal control plan is formulated as linear integer programming problem. Microscopic simulation results of two arterial test cases revealed that traffic control strategies developed using the proposed framework led to tangible performance improvements when compared to signal control strategies designed for operations in under-saturated conditions. The generated control plans successfully manage to allocate queues in network links.
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