Suggested Citation:
Ma, Jingtao and Michael Zhang (2008) An Efficiency-Equity Solution to the Integrated Corridor Control Problem. Institute of Transportation Studies, University of California, Davis, Research Report UCD-ITS-RR-08-51

Efficiency has been considered as the single most important measure in designing traffic control systems for over five decades. As traffic congestion spreads wider and spans longer in most urban areas, the traveling public is more and more concerned with how the benefits from the new control design or existing control system updates are distributed among them; and the systems that favor certain groups over the others are certainly considered “inefficient” to the disadvantaged groups. Within this context, an efficiency-equity bi-criterion corridor control design program is developed in this study. Firstly a network flow dynamics study tool based on the finite difference solution to the kinematic wave model has been developed, with prevalent control measures including signal controllers, ramp meters and priority rule controls adapted in a coherent manner. The system efficiency measures, the user equity measures at both aggregate and disaggregate levels are then developed and calculated based on the flow dynamics model. The bi-criterion control program has been solved by a heuristic search method to compute the signal green split and ramp metering rates. The numerical experimentation indicates that 1) the system efficiency measure is independent from the user equity measures to a great extent; 2) using only the disaggregate equity measure cannot characterize the user equity holistically, and rather both aggregate and disaggregate equity measures must be present simultaneously; 3) the introduction of equity measures can be well justified from the analysis of the relative gains and losses of system efficiency and user equity.