THE congestion charge is to be extended to busy roads across London under plans to use electronic tags in windscreens to monitor vehicle movements.

Thousands of gantries will be erected over roads to detect passing vehicles and automatically deduct payment from the driver’s pre-paid account.

Transport for London plans to extend the new charging system to congested urban centres, Thames bridges and strategic routes across London as well as to the existing zone and its western extension.

Drivers would be charged different rates according to the time of day, with the top rate reserved for morning and evening peak periods.

Charges would also vary according to the size of the vehicle, with drivers of cars that cause more pollution paying more. Drivers travelling against the main flow of traffic, such as night workers leaving Central London in the morning, would receive a discount on the existing £8 flat rate.

The credit-card-sized tags would cost about £5 and could be topped up by direct debit. Drivers could pay using existing methods, but would not benefit from the cheaper rates.

Motorists who chose tags would also no longer have to remember to pay the charge. Most of the 5,000 drivers a day who incur £50 fines at present are thought to have forgotten to pay or not to have known that they were liable.

Last month TfL began a six-month trial involving 500 buses, vans and council vehicles with tags. It has also installed 19 gantries in South London between Southwark Bridge and Tower Bridge. The gantries contain beacons which detect the tags and cameras to catch those fail to pay.

Initial results indicate the technology is working well and TfL hopes to introduce it across Central London in 2009, when it renews the contract for running the congestion charge.

TfL intends to begin to use the system in other congested parts of London from 2010. It has identified “key centres”, which it believes might benefit from congestion charging. They are Harrow, Hounslow, Kingston, Sutton, Croydon, Bromley, Ilford, Romford and Wood Green.

The tag and beacon trials are being watched by other local authorities that are considering congestion charging, including Greater Manchester, West Midlands, Tyne & Wear, Cambridgeshire, Durham, Shrewsbury and a coalition of councils around Bristol and Bath.

TfL is also preparing for the more radical step of using satellite tracking to charge drivers for each mile they travel.

Michele Dix, TfL’s congestion charging director, said that satellite technology was not yet reliable, but was likely to be ready by 2014.

She said congestion across Greater London could be cut by 40 per cent by introducing charges of 60p a kilometre in the centre, 30p in inner London and 15p in outer London. A journey across the city, for example from Barnet to Epsom, would cost about £13.

Ms Dix said rising traffic levels made it essential to consider more sophisticated charging systems. The number of daily car journeys in London would grow by almost a million by 2025 unless charging was extended across the capital.

She admitted that the gantries for tag and beacon charging would add to the clutter of signals and posts on London’s streets. “We are working at making the posts more slender so that they look more like lamp posts,” she said.

COUNTDOWN

2003, February 17 £5 congestion charge introduced in Central London
2005, July 4 charge increased to £8
2007, February 19 charging zone to extend westwards, doubling in size
2009 tag and beacon charging likely to be introduced
2010 charging extended to busy roads across London
2014 satellite charging introduced, costing drivers up to 60p per kilometre