"In the first official update of the effect of the scheme, the mayor's Transport for London authority will publish a study showing a 40% reduction in congestion during charging hours, compared to its own expectation of 20% to 30%. The detailed analysis suggests traffic entering the central zone has fallen by a fifth, while the number of vehicles moving around inside the zone is down by 16%. Speeds have risen to 11mph, compared to 8mph at the same time last year. However, the figures are likely to fuel criticism that the charge has been so effective that it is sucking the lifeblood out of businesses in central London."
Thanks to Chris Steins