LONDON BRIEFING by Chris Johns: London embarked on a rare experiment this week, charging motorists £5 (€7.44) for the privilege of entering central London during "peak" hours.

Ken Livingstone's congestion charge will, according to his web-site, "reduce traffic, make journeys and delivery times more reliable, and raise funds to re-invest in London's transport system".

If it achieves only one of these aims, it will probably be judged to have been a resounding success. Nevertheless, it has been roundly condemned as just another tax on motorists that will have little impact on anything other than revenues available to London's mayor to waste.

It is easy to sympathise with the critics. A reduction in congestion can only come about by people abandoning their cars for buses or trains.

If either service was adequate, few people would endure road congestion in the first place. Without significant upgrading of alternative transport arrangements, there is little point in trying to force people to swap one bad option for an equally miserable alternative.

The tube system, in particular, exists in a permanent state of near-collapse anyway. The slightest additional stress on that network, from whatever source, produces chaos. If motorists really do decide to leave the car at home and catch the tube, the system will simply fall apart.

The mayor has promised to spend the money raised from congestion charging on upgrading the buses but most people see motorists as unlikely candidates for a voluntary switch from air-conditioned comfort to strap-hanging on the number 73.

Critics make the point that if motorists are freely choosing to endure traffic congestion, all that tells you is how bad the alternatives are. And £5 a day is unlikely to alter that particular calculus in any material way. If the congestion charge has any impact it will merely be to move the congestion somewhere else.

Londoners are entitled to ask just how did things get this bad? Most major cities throughout the world suffer from some of these problems but London seems to have them writ large with no redeeming features (although perhaps not as bad as Bangkok, where there is a booming roadside business in selling empty plastic bottles to male drivers).

Many other British cities, let alone foreign ones, have much better transport infrastructures. London's problems could eventually threaten its status as a global financial centre.

London's main problem has been the lack of a single authority willing and powerful enough to tackle the obvious problems.

Since Margaret Thatcher abolished in the 1980s the last institution that performed that role - run, ironically, by Ken Livingstone - Londoners have lost out in the regional battles for funding and other resources necessary to keep things running.

Over the last two decades the decline has been slow but inexorable. Londoners pay more taxes that anybody else but the money tends to be spent elsewhere.

In recognition of this, Tony Blair agreed to the creation of a Mayor of London - provided it wasn't Ken Livingstone.

When his party and the electorate begged to differ, the prime minister made sure that the new mayor had no powers to actually do anything. Run the tube? Forget about it.

Livingstone's transport supremo, Bob Kiley, the man who restored the New York subway to something like its former glory, claims that Gordon Brown doesn't exist. The UK Chancellor has, apparently, refused all contact with anybody from the Greater London Authority. The deputy prime minister is not called Two-Jags Prescott because he gets the bus to work.

Ken Livingstone is right. Something has to be done. Building new roads is not an option, so getting people out of their cars and onto public transport is the only possible way to go. And that is achieved by spending lots of money on buses and tubes and taxing motorists more - or legislating people off the roads.

Other cities have imposed a mix of congestion charging and simple laws to restrict cars. And generally it works.

Everybody in Britain knows that there really is no alternative. Nowhere in Europe is congestion worse. Blair is simply waiting to see if the particular scheme chosen by Livingstone works. If it does, the government will try to take the credit and introduce similar schemes in other cities. If it flops, the prime minister will gladly bury his capital city's mayor.

Even then, the view will be that failure will have occurred because the scheme was faulty in detail, rather than principle.

Whatever happens from here, schemes to keep motorists out of the centres of our larger cities are here to stay.

Chris Johns chief strategist, ABN AMRO Securities, London. All opinions expressed are entirely personal.

cjohns@eircom.net