Georgia Institute of Technology
John Bartholdi is the Manhattan Associates Chair in Supply Chain Management and the Director of the Research Program of the Supply Chain & Logistic Institute’s at the Stewart School of Industrial & Systems Engineering at Georgia Tech.
Dr. Bartholdi teaches supply chain issues, primarily warehousing, at both the undergraduate and graduate levels and in SCL’s professional education program. His research centers on problems in warehousing and distribution, but he reserves some time to pursue wider-ranging interests, including mechanics, politics, computer science, geography, and biology. Dr. Bartholdi was named a “Presidential Young Investigator” by the National Science Foundation for 1984-1989. His research work has been supported by the Defense Logistics Agency, the Office of Naval Research, and the Air Force Office of Scientific Research, among others.
Dr. Bartholdi graduated in 1968 with a B.S. degree in mathematics from the University of Florida and then served two tours of duty in southeast Asia as a paratrooper in a Naval Special Warfare unit. He returned to the University of Florida to complete the Ph.D. program in operations research in 1977 and later served on the faculties at the University of Michigan, the Shanghai Institute of Mechanical Engineering, and the National University of Singapore.
Self-coordinating buses improve service
The main challenge for an urban bus system is to maintain constant headways between successive buses. Most bus systems try to adhere to a schedule, but the natural dynamics of the system tend to collapse headways so that buses travel in bunches. We have devised a method of coordinating buses that abandons the idea of a target schedule or even any target headway and instead allows equal headways to emerge spontaneously. Our scheme is based on the designation of certain stops as “check points”, at which we may require a bus to pause briefly. The duration of the pause is computed from local information about the arriving bus. Under very general conditions headways tend to equalize, and without direction by management or intention or even awareness of the drivers. Our scheme has controlled buses on the Georgia Tech campus for the past three years. This talk briefly recapitulates the technical ideas and then focuses on how they had to be adapted to the inevitable real-world complications, such as surges in traffic density, turnover among drivers, and unreliable GPS.