Work led by Professor Colin Green, looking at data on road accidents in London and 20 other most highly populated towns and cities in Great Britain between 2000 and 2010, backs up the idea that the congestion charge, together with earmarking the revenue for mass transit, has fundamentally changed travel behaviour.

Before February 2003 and the introduction of the charge, the average speed in the charge zone was 8.6 mph (with a third of journey time spent in being entirely stationary). Speeds have now increased to an average 20 mph.

Since 2003, the London congestion charge zone now sees, on average, 30 fewer traffic accidents per month compared with the average in the 20 other cities. The research also shows the dramatic fall is also replicated in terms of serious accidents, with an average 46 fewer fatalities each year; and that rather than causing 'knock-on' problems, the benefits have been felt generally in London, in the 'spillover' areas surrounding the congestion zone, where there have been an average 18-20 fewer traffic accidents each month; a decline in numbers of accidents among 'non-chargeable' vehicles such as taxis and bicycles; as well as 'out of hours' in the evenings and weekends when the charge isn't in place.