As cities around the world grapple with seemingly insatiable travel demand, simply expanding roadway capacity to meet demand is no longer a viable solution. Thus, many cities have turned to newer, technology-based solutions to mitigate demand for travel.
One such solution is congestion pricing. Congestion pricing involves setting up a cordon zone around a certain area in a city, usually the Central Business District, and then charging vehicles that enter the cordon zone a toll during certain times of the day. Cities utilize electronic tolling technology to setup the cordon zones and charge vehicles. Currently, Singapore, London, United Kingdom, Stockholm, Sweden, Milan, Italy, and Gothenburg, Sweden have active congestion pricing schemes, with several other cities actively studying the concept.
This meta-study conducted a careful review of available data and literature on the five currently active congestion pricing schemes around the world. This study relied on publicly available data about each congestion pricing scheme and previous studies of these congestion pricing schemes.
This study found five key lessons learned from implementation of congestion pricing. These lessons are:
- Vehicle exemptions are highly consequential and often increase traffic to a surprising degree. Nearly all congestion pricing implemented various exemptions for certain types of vehicles such as electric cars, taxis, carpools etc. In all cases, these exemptions proved to have more negative consequences than authorities expected. In most cases, authorities had to rescind or tighten these exemptions to keep congestion to manageable levels.
- Increasing vehicle surcharges has a mild effect compared to initial surcharge implementation. Overall, in all cases, the initial surcharge caused the biggest drop in traffic. After that, increases in the surcharge price only had a small, incremental impact on traffic volumes. This suggests people are most sensitive to the idea of being charged any amount of money and that subsequent price increases have a more marginal effect.
- Congestion pricing is compatible with other demand management projects. No city implemented congestion pricing alone. Cities typically implemented other transportation demand measures such as park-and-ride schemes, carpool initiatives etc. Cities also invested toll revenues in multi-modal transportation projects like bike lanes.
- Congestion pricing can be traced to an unusual political event that serves as a catalyst. Congestion pricing was only implemented after some sort of change in the political environment of the cities. For example, London was able to implement congestion pricing only after the British government gave the Mayor of London broad powers over transportation in London.