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School of Civil and Environmental Engineering
Ph.D. Thesis Defense Announcement
Modeling and simulation of congestion control strategies on freeways:
pricing, ramp metering, and variable speed limits
By
Hyun Woong Cho
Advisor:
Jorge A. Laval
Committee Members:
Dr. Michael Hunter (CEE), Dr. Angshuman Guin (CEE), Dr. David Goldsman (ISyE),
Dr. Bhargava Rama Chilukuri (IIT, Madras)
Date & Time: Thursday, July 6th, 9:00am
Location: Sustainable Education Building Conference Room 122
This dissertation studies the modeling and simulations of demand- and supply-side management strategies to reduce freeway congestion. The first part of this dissertation analyzes real-time pricing strategies to control the demand to a managed lane facility, such as an HOT lane. We devise a system-optimal real-time congestion pricing strategy able to handle variable capacity because of the weaving activity. It is found that the proposed model outperforms existing methods in minimizing total delay savings, particularly when bottleneck capacities varied significantly. The method is simple to implement with current technology.
The second part of this dissertation studies supply-side strategies. It proposes a variable speed limit and ramp metering (VSL-RM) control strategy to prevent and recover from losses in freeway capacity at freeway merge bottlenecks. Using kinematic wave theory, this study derives analytical models that are implemented into the microsimulation model GTsim. It is found that the combined VSL-RM system outperforms either component in isolation for preventing traffic breakdown; if only one component has to be used, its choice depends on the distribution of traffic demand.
The third part of this dissertation is a case study that implements the VSL-RM strategy to a real-life freeway corridor in Atlanta. Using a stochastic simulation-based optimization framework that combines GTsim and a genetic algorithm-based optimization module, we determine the optimal parameter values of the combined VSL-RM system that minimize total vehicle travel time.
