Bus Transit Operations Control: Review and an Experiment Involving Tri-Met’s Automated Bus Dispatching System

Journal of Public Transportation Article in Volume 4, Issue 1 (2001) by James G. Strathman, Thomas J. Kimpel, and Kenneth J. Dueker, Center for Urban Studies, Portland State University and Richard L. Gerhart, Kenneth Turner, David Griffin, and Steve Callas, Tri-Met, Portland, Oregon        


Tri-Met has implemented an automated bus dispatching system (BDS) employing satellite-based automatic vehicle location (AVL) technology. The BDS is capable of facilitating real-time operations control actions to improve service regularity. This article focuses on a service regularity problem that often occurs during peak periods when regular service is augmented by extra-board trips (“trippers”). In this case, “bus bunching” results when regular service trips experience departure delays while trippers depart on schedule. With the aid of BDS information, field supervisors stationed at a key location on Portland’s (Oregon) bus mall used holding, short turning, and reassignment actions to maintain headways on six selected routes. Analysis of their efforts reveals an improvement in service regularity as well as a leveling of passenger loads.