London's congestion charging scheme was launched on Monday with no sign of the predicted gridlock.

Traffic appeared to move freely in the streets around the capital, although the school half term reduced the usual volume of vehicles on the road.

The relatively successful start came despite predictions from mayor Ken Livingstone of a "bloody" first day for the scheme.

It is the largest road charging scheme of its kind in the world and central government is watching closely to see if it works.

The Conservatives manned a series of protests at points across London where the charging zone begins.

The party's candidate for the mayoral election, Steve Norris, has pledged to scrap the system.

"The crazy thing about the scheme is that even if it works it doesn't work," he said.

"It's a tragic waste, you know, of over £200 million on technology which nobody in their right mind would have recommended.

"There are a huge number of things we should be doing right out there on the street, they're simple, they don't cost that kind of money, they don't have those sorts of hard cases that we're now seeing coming through, cases of real distress."

Tom Brake, the Liberal Democrat London spokesman, said the scheme had long-term benefits.

"The chaos predicted on London's roads has not yet materialised. This is a promising start for congestion charging but it is too early to say whether the scheme has succeeded," he said.

"Congestion charging should be a win-win situation for Londoners; better public transport, cleaner air and more reliable journeys."

Experts have warned that it is almost impossible to measure whether the charge will cut traffic levels because of fluctuations in vehicle speeds due to other factors.

Rod Kimber, a director at the Transport Research Laboratory, said: "It depends very much on fluctuations... in the numbers of road works, the way traffic is managed, or major events like economic shocks. There won't be meaningful measurements for at least a year, if ever."

Supporters of the scheme claimed London cannot continue to find room for more cars and lorries.

Professor David Begg, chairman of the Commission for Integrated Transport, said the scheme could result in the most radical re-think of the way we pay for road use across the UK.

"Ministers need to give a lead and the rest of us need to join in and think constructively before traffic congestion gets a stranglehold on the whole economy. The issue is not going to go away. We must confront it and resolve it," he said.

Some MPs have also given their support to the new system.

Birmingham MP Lynne Jones has been travelling to work at Westminster by bike as a way of beating the charge.

"The introduction of the congestion charge has finally motivated me to get on my bike. The last three weeks have been a successful trial period and I am now hooked on this mode of transport for getting around urban areas. I also feel fitter!" she said.