Empirical assessment of bottleneck congestion with a constant and peak toll: San Francisco–Oakland Bay Bridge

Abstract

Extensive theoretical research has been conducted on the morning commute problem building on the bottleneck model (Vickrey in Am Econ Rev 59(2):251–260, 1969). There have been far fewer studies assessing the bottleneck model and its extensions using real data. This paper presents an analysis of empirical data from the toll plaza of the San Francisco–Oakland Bay Bridge, which is a major regional bottleneck. The Bay Bridge transitioned from a constant toll to a peak step toll on July 1, 2010, so the site is well-suited for assessing many relevant extensions to the classic bottleneck model for the morning commute, including theories for congestion pricing. This paper uses traffic data from the Bay Bridge to address two areas of theoretical work on bottleneck congestion: (1) heterogeneous schedule preferences, and (2) equilibrium response to step tolls. The results suggest that the predicted equilibrium for the morning commute is consistent with observed traffic patterns, especially at the beginning of the rush. The data can be analyzed through the lens of relevant theories to quantify commuters’ value of earliness and lateness relative to queuing delay. The pattern of queuing suggests that the peak step toll has not been implemented in a socially optimal way.