Congestion fees are working in central London

Ben Muse links to a summary of current knowledge.  Here is one bit:

The aim of the congestion charge was honest and explicit: to reduce traffic congestion by reducing traffic volume by 10 to 15 per cent. To achieve this, drivers are required to pay £5 per day if they enter central London between 7am and 6.30pm, Monday to Friday. In the event the reduction in traffic has been greater than anticipated. Overall traffic entering the zone is down 18 per cent during charging hours, with a reduction in car traffic of 30 per cent and a similar reduction in congestion. There has been little displacement of traffic into areas round the zone or additional congestion on the ring road. Motorists themselves have benefited; for those who still drive in the zone, journeys are quicker and more reliable…