A strategy to reduce urban congestion, first used in Singapore in 1978. An electronic road pricing (ERP) system can electronically monitor, and track, vehicles entering a restricted zone to control the flow of inbound traffic. The system is capable of automatically imposing a demand-sensitive congestion toll on every vehicle without requiring them to slow down or stop, when the congestion level in the restricted zone exceeds a preferred threshold level.

The ERP system was first tried out in Hong Kong from July 1983 to March 1985, but not implemented due to public rejection, arising from concerns over the privacy of movement. In Singapore, on the first day of its implementation (1 April 1998), the usual morning rush hour traffic along one of the heavily congested highways decreased by 17% (Goh (2002) J. Transp. Geog. 10, 1). Road pricing varies in coerciveness depending on households’ economic resources, and the public perceive road pricing as unfair, given that wealthy households are not forced to adapt (Jones in J. Schade and B. Schlag, eds 2003). Jakobsson et al. (2000) Transp. Policy 7, 2 find that lower-income groups find road pricing less acceptable than high-income groups because it affects their perceived freedom and justice negatively. A. Mahendra, ed. (2010) is useful on the impacts of road pricing on business.