At the same time, Transport for London is planning a crackdown on enforcement of fines for drivers who don't pay the £5 daily charge, which it hopes will bring in another £20m a year.
If the scheme is extended to cover west London, mayor Ken Livingstone is expected to keep the system which lets about half of all drivers escape most or all of the daily charge. But TfL said the reductions could not be kept if it gets permission for a proposal to charge motorists on all roads across the capital.
At a conference to mark the first six months of the £5 daily charge, TfL said the scheme had cut traffic inside the ventral zone by 14 - 15% and cut congestion - measured as delays to journeys - by double that.
100 CONGESTION FINES FOR DRIVER NEVER IN LONDON
A teacher living 200 miles from London has racked up 100 congestion charge fines even though she hasn't visited the capital in more than 20 years, reported The Mail on Sunday (p49).
Lynn Bradbury has been swamped with penalty charge notices - sometimes as many as three a week - since the road toll's launch in February. She is among 26,000 motorists being pursued by bailiffs for non-payment.
Each time a new letter arrives, Mrs Bradbury, 52, an English teacher from Oldham, has to fill in a lengthy form to appeal against the fine. However, twice she was away and unable to return the appeal forms. As a result, she had to appear at Oldham County Court twice to swear she had not been in London. Yet Mrs Bradbury has still been warned she could face a visit from the bailiffs to claim £250 in outstanding fines.
She said: 'I can't even phone through to speak to someone because the congestion charge number goes through to an automated system that only allows you to pay the charge. Now I have referred this matter to my solicitors in case they send the bailiffs'.
More than 850,000 penalty tickets have been issued since the scheme's launch.
Police have told Mrs Bradbury her number plate has probably been 'cloned' by criminals. Mayor Ken Lingstone's officials estimate that up to 500 vehicles regularly use other people's number plates inside the zone.
Transport for London said at the weekend all Mrs Bradbury's fines had been cancelled and apologised for her problems.