Suggested Citation:
Shen, Wei and Hongjun Michael Zhang (2010) System-wide Ramp Metering as a Policy Tool to Induce Efficient Travel in a Freeway Corridor. Institute of Transportation Studies, University of California, Davis, Research Report UCD-ITS-RR-10-41

In a congested transportation network, a traveler’s trip can cause additional delays to other travelers who enter the network later. Due to the presence of this congestion externality, the departure time and route choices of travelers who seek to optimize their own travel experience usually lead to inefficient temporal and spatial traffic distribution in a transportation network in terms of social welfare. This ‘welfare gap’ between the Wardropian user equilibrium (a product of selfish choices) and system optimum traffic patterns can be, in theory, eliminated by internalizing the congestion externality via marginal cost pricing.