Here's info from Wikipedia:
"The London congestion charge is a fee for some motorists entering the Central London area. As of 2006 it is the largest city to have adopted a congestion charge model. The organisation responsible for the charge is Transport for London (TfL). The fee was introduced on 17 February 2003<1>. Initially set at £5, then raised on 4 July 2005 to £8 <2>, the daily charge must be paid by the registered keeper of a vehicle that enters, leaves or moves around within the congestion charge zone between 7am and 6.30pm, Monday to Friday. Failure to pay the charge means a fine of at least £50."
http://en.wikipedia.org/wiki/London_congestion_chargeThe intention is good, but it does nothing to address the problems with alternative modes of travel. The British rail system for instance has been privatized, and is beset with so many deficiencies on the congested routes into London for the price of the ride that it's like paying someone to torture you. Network Rail, the company overseeing the system, is subsidized with £6bn per year in taxpayer money; that doesn't include the cost of the rail ticket which, unless you live close to London, you won't get for less than the daily congestion charge. And then there's the price of parking at the station.
Here's an example I found: annual season ticket Milton Keynes to London (with travelcard) = £4220. Annual season ticket Milton Keynes Central car park = £944. The average number of workdays in the UK is 233, so that means somebody living in Milton Keynes who travels to London daily by train and uses the parking lot will pay £22/day. Even if they walk or otherwise to the station, that's still £18/day.
And what are you paying for? In most cases trains without a/c, with seats ripped out so more people can cram in, antiquated stations, not to mention delays and cancelled service for things like snow on the tracks. No kidding. Last week one line was shut down over nothing more than a dusting. And when I lived there, service was notoriously cancelled one day because of "the wrong kind of snow on the tracks". (Or was it leaves? That's happened too.)
Some will suggest raising the congestion charge. That might be fair -- once the government can offer halfway decent alternatives to driving into London.
edit: I'm afraid I made it sound like it costs that much more to take the train than to suffer the congestion charge, which isn't quite right when you figure in the costs of petrol and parking in London (very expensive). What I'm saying is that there's little real incentive for people to get out of their cars and take the train.