In a bid to reduce traffic congestion, London Monday introduced a controversial tax on most vehicles entering the heart of the city. Analysts say London's so-called congestion charge is the most ambitious and sophisticated attempt by any city to reduce traffic problems.

Driving into London's crowded 21-square-kilometer city center after 7:00 am in the morning now comes at a price: five pounds sterling, or $8 a day. Offenders could face a stiff additional penalty of $130 for failure to pay the charge. Payment is made by telephone, the Internet or at designated pay-points around the city. To ensure that no vehicle avoids the charge, hundreds of cameras have been set up to photograph the license plates of all vehicles entering the city center.

However, some vehicles are exempt from the charge, including taxis, buses, electric cars, motorcycles, and emergency services vehicles.

London's Mayor Ken Livingstone argues the dramatic measure is necessary to ease gridlock in the British capital, where traffic speed averages just under 16 kilometers per hour and in some places crawls to a mere three kilometers per hour, slower than a horse and cart. Mr. Livingstone says he hopes the so-called congestion charge will not only decrease traffic, but will also raise needed funds to improve public transportation.

The top official responsible for London Transport's Congestion Charge, Michele Dix, says day one of the plan has gone smoother than expected and traffic levels are lighter.

"If it reduces traffic levels it will be judged to be a success," she said. "The revenues are regarded as sort of an additional benefit and certainly if we are getting the traffic levels as predicted - 10 to 15 percent - then we are on target to get about 130 million net revenues per annum which will allow us to buy many transport improvements across London."

Ms. Dix says the plan will be judged in six months time.

London School of Economics student Victoria Packett supports the congestion charge, saying it will cut down on traffic jams and pollution.

"Anyone who lives in London is going to be walking or using public transport, so I think it is very selfish of people to complain about being charged for driving from outside London because they are just clogging up the roads for everyone else," she said.

But opponents of the charge, and there are many, like London cabbie, Mike Smith, say the charge will only put more pressure on London's overcrowded buses and rickety underground, or subway. He also says the tax is not high enough to keep cars out of the city.

"I don't think it is going to work," he said. "Five pounds is not enough. Five pounds is what? It is about 20 minutes on the parking meters. You might as well make it 10 to 15 pounds to deter people."

Analysts say London's plan to tame its traffic has begun smoothly largely due to the start of a school holiday which is cutting back on the volume of cars. They say the real test will come when the holiday ends in two weeks. Still, the plan is being closely watched by other cities not only in Britain but around the world as a possible model to end urban gridlock.