Document Type


Date of Award

Fall 1-27-2008

Degree Name

Doctor of Philosophy in Transportation - (Ph.D.)


Executive Committee for the Interdisciplinary Program in Transportation

First Advisor

I-Jy Steven Chien

Second Advisor

Athanassios K. Bladikas

Third Advisor

Lazar Spasovic

Fourth Advisor

Paul Miron Schonfeld

Fifth Advisor

Janice Rhoda Daniel

Sixth Advisor

Kyriacos Mouskos


Highway maintenance activities usually require lane closures and disrupt traffic operations. Because of budget constraints, project deadlines, and the resulting traffic impact, the objective of this dissertation is to improve the efficiencies of traffic operation and maintenance work, and minimize the total project cost (i.e., agency cost and road user cost) by optimizing work zone schedules.

This dissertation focuses on the maintenance projects on multiple-lane highways. The objective total cost function is formulated while considering a discrete maintenance time-cost function and time-dependent traffic diversions. However, the work zone scheduling problem is a combinatorial optimization problem and difficult to solve analytically. This dissertation transformed the complicated problem into two separate steps: determining the time-dependent traffic diversion by the User Equilibrium Assignment, and minimizing the total project cost by a Genetic Algorithm. An iterative algorithm that integrates the two steps was developed. The optimized work zone schedule and the associated optimal diverted traffic flow can be found simultaneously after multiple iterations.

Case studies and extensive sensitivity analyses were conducted to analyze various scheduling scenarios with or without a time-cost function and traffic diversion. The relations among key decision variables were analyzed. Conclusions and recommendations are provided, and directions of future research efforts are discussed.



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