Publication Type

Journal Article

Publication Date

5-2014

Abstract

The fundamental law of highway congestion states that when congested, the travel speed on an expanded expressway reverts to its previous level before the capacity expansion. In this paper, we propose a theory that generalizes this statement and finds that if there exists a coverage effect, that is, the effect of longer road length on traffic conditional on capacity, then the new equilibrium travel speed could be lower than its previous level. Given the fundamental law, the theory predicts that the elasticity of traffic to road capacity is at least 1. We estimate this elasticity for national expressways in Japan and test this prediction. Using the planned national expressway extension as an exogenous source of variation for capacity expansion, we obtain elasticity estimates ranging between 1.24 and 1.34, consistent with the prediction of our theory. We further investigate the sources of the larger-than-unity elasticity and find that the coverage effect plays a critical role, compared with the effect due to lane expansion.

Keywords

Traffic congestion, Fundamental law of highway congestion, Returns to scale, Speed function, Coverage effect, Japan

Discipline

Asian Studies | Public Economics | Transportation

Research Areas

Applied Microeconomics

Publication

Journal of Urban Economics

Volume

81

First Page

65

Last Page

76

ISSN

0094-1190

Identifier

10.1016/j.jue.2014.02.002

Publisher

Elsevier

Copyright Owner and License

Authors

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Additional URL

http://doi.org/10.1016/j.jue.2014.02.002

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