Congestion charging is a technology designed to restrict traffic entering very congested urban areas, especially during peak hours. Congestion charging works by using electronic tolling equipment to cordon off an area of a city, usually the Central Business District, and charge drivers a toll for driving into the cordon area. Congestion pricing typically only operates during peak hours but can operate 24/7. Currently five cities have congestion pricing schemes, and more are considering them.
A research team studied the effect of congestion pricing on safety. To do this the team evaluated the removal of the Western Extension of the Congestion Charge Zone in London. Essentially, after officials in London implemented the original charge zone they extended the charge zone west to encompass more of the city. However, the Western Extension was controversial and removed in 2010.
Using this removal as a basis for this study, the research team gathered detailed crash and demographic data about different areas both inside the current charge zone and inside the former Western Extension. The team then used various statistical methods to compare crash rates between similar areas in the current zone and the former Western Extension.
The team found:
- Congestion charging reduced crashes by 46 percent within the cordon area.
- Immediately adjacent to the cordon area (within 1.5 km) crashes were still 16 percent lower.
- Lower traffic volumes and lower speeds resulting from congestion pricing likely led to the safer driving conditions.