The effect of the London congestion charge on road casualties: an intervention analysis

The introduction of the congestion charge in central London on the 17th of February, 2003, led to a reduction in congestion. One factor that has not been fully analysed is the impact of the congestion charge on traffic casualties in London. Less car travel within the charging zone may result in fewer traffic collisions, however, as the number of pedestrians, cyclists, and motorcyclists increased after the introduction of the congestion charge, the number of traffic casualties associated with these groups may also have increased. Reductions in congestion can also lead to faster speeds. Therefore, there could be increases in injury severity for those crashes that do occur. An intervention analysis was conducted to investigate the effect of the congestion charge on traffic casualties for motorists, pedestrians, cyclists, and motorcyclists, both within the charging zone and in areas of London outside the zone. This was done for killed and serious injuries (known as KSI in British terminology) and for slight injuries to examine whether there were any shifts in severity outcomes. Our results suggest no statistically significant effect for total casualties in London, but within the charging zone there has been a statistically significant drop in motorist casualties, and possibly an increase in cyclist casualties. There is an associated effect of an increase in casualties of motorcyclists and cyclists in some areas outside the charging zone, suggesting that changes in the design of the congestion charge may be needed to achieve reductions in casualties.

Mohammed A. QuddusEmail:

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Dr. Robert B. Noland   is Reader in Transport and Environmental Policy at the Centre for Transport Studies at Imperial College London. He received his PhD at the University of Pennsylvania in Energy Management and Environmental Policy and previously was a Policy Analyst at the US Environmental Protection Agency. Dr. Mohammed A Quddus   is a Lecturer in Transport Studies at Loughborough University. Prior to this he was a Research Assistant at Imperial College London where he obtained his PhD in 2006. His main research interests are in road transport safety, geographic information science and its application to transport planning. Dr. Washington Y. Ochieng   is the Reader in Geomatics and Transport Telematics at Imperial College London. He is the Director of the Engineering Geomatics group that carries out research in ATM-ATC, positioning and navigation, and transport telematics. Dr. Ochieng holds BSc (Eng), MSc and PhD degrees in space geodesy.