Mayor's pledge over car charge

London's new £5 a day congestion charge could be scrapped within two months of operation if it fails to work properly, Mayor Ken Livingstone pledged today.

The controversial and hugely costly scheme will be binned without hesitation if it proves to be a "demonstrable failure" within a probation period of as little as eight weeks, he said.

The concession, which will come as a relief to millions of anxious drivers, was revealed by Mr Livingstone this morning - a day after he gave the formal decision to press ahead with the charge.

He said it would be "perverse" to continue with the toll to enter central London if it was leading to daily traffic chaos across the capital.

Speaking at Mayor's question time, Mr Livingstone said: "There will be a difficult first two months with teething problems as there is with any transport scheme, but at the end of the two months it will be clear whether it is going to settle down or not. Nobody has ever done a scheme like this before and it would be perverse to continue with it if it was not working."

Mr Livingstone said that no fixed trial period had been set, and it could be six months rather than two. But his willingness to abandon what many say will be his only significant project in office reflects the huge step into the unknown that the scheme effectively amounts to.

No other congestion charge scheme anywhere in the world comes close to the size, scope or sophistication of the one planned for London, and officials admit there is no way of knowing if it will work.

Some critics have already suggested the computer technology - one of the most problem-prone components of the scheme in its infancy - should have had a test run in one section of the city. Mr Livingstone also said that a team of independent assessors will be appointed to help him judge if the scheme, which should be operational next year, is proving a longterm success.

In a further attempt to "sweeten" the scheme, Mr Livingstone also said the estimated £130 million annual revenue it could raise might be spent according to a voting system in which Londoners could participate.

At the question-time session, the Mayor also upped his threat of a new war over the planned Tube partprivatisation, saying the promised improvements were so poor he could still refuse to sign the contracts.

In the strongest hint yet that he still plans a fight over the scheme, Mr Livingstone said "no reasonable person" could be expected to agree to the terms of the contracts as they currently stood.

His transport officials are taking legal advice on whether they can legitimately refuse to do so.