William Vickrey

William Vickrey appears as the most important advocate of congestion pricing, the principle that drivers should face the costs their use of scarce road space imposes on everyone else. His idea turns traffic from a queue people endure into a coordination problem: prices can make the tradeoffs visible and prompt people to travel at different times, take public transportation, or choose another route.

Congestion as a Pricing Problem

Congestion pricing had existed as an idea since the 1920s, but Vickrey supplied its clearest economic rationale. Road space, in his account, is a scarce resource; allocating it wisely requires making the costs and benefits of each person’s choices apparent to that person. When a main route is free, drivers have reason to choose it during rush hour even when the group would be better off if some traveled earlier or later, used public transportation, or worked from home. A toll changes the decision by asking each driver, in effect, how much the trip is worth.

The point is not simply to charge motorists. A price can distribute demand across time and alternatives, replacing the unpriced rush-hour rush toward the same road with choices that account for their effects on others. The model therefore treats traffic not only as a transportation problem but as a problem of coordinating separate decisions.

The Political and Practical Test

The book contrasts Vickrey’s proposal with London’s 2003 congestion charge, which charged £5 to enter central London between 7 a.m. and 6:30 p.m. The plan faced major lobbying opposition, while congestion pricing in the United States had generally been politically unacceptable. Many commuters felt they had little choice about when or how to travel, and the prospect of wealthier drivers buying faster journeys was especially contentious. In the account, voters and politicians had to be convinced that no alternatives remained before they would accept such a scheme.

Resistance was striking because variable pricing was familiar elsewhere: long-distance calls cost more during the day, drinks less during happy hour, and trips to Las Vegas more on weekends. Driving, by contrast, was often expected to carry no monetary price, even when demand was highest. The comparison reveals the political difficulty of applying a readily accepted pricing principle to a shared road.

London’s results suggested that even a relatively simple charge could affect travel substantially. Traffic fell by almost 20 percent, congestion declined, and one study found that cars could travel 40 percent faster, though their speed still averaged only eleven miles an hour. Those outcomes also raised a design question: the aim is not to empty roads, but to balance the benefit of driving against the congestion costs imposed on others.

From Fixed Tolls to Responsive Prices

Vickrey imagined a more finely adjusted system than London’s flat £5 charge. Under responsive pricing, a road’s cost could change with current traffic, weather, or vehicle type. If a broken-down tractor trailer suddenly clogged I-5 between Sacramento and San Francisco, a higher price could divert some drivers to other routes and keep the congestion from worsening. Traffic sensors in highways and global positioning systems in cars made such adjustments technologically feasible, though the account notes that real-time pricing remained politically difficult and might burden drivers with complicated calculations.

Pricing also raises questions of fairness. People with more money can more easily trade it for time and convenience, while avoiding a toll does not necessarily improve poorer commuters’ circumstances. A workable system therefore has to consider how to return revenue to public transportation or otherwise distribute its benefits. The London plan committed substantial funds to public transportation; Singapore paired its system with a modern mass rapid transit network. These examples underscore that Vickrey’s central insight concerns incentives, but the design of a just and effective policy must also address who pays, who benefits, and what alternatives are available.