This is the worst jam in London say taxi drivers

This line of stationary vehicles was today branded London's worst traffic jam by taxi drivers.

They urged Mayor Boris Johnson to step in after rephasing of traffic lights at a vital West End junction last month led to lengthy delays at the intersection of Holborn and Procter Street.

Instead of allowing traffic on different legs of the major gyratory to move in turn, an "all-red" phase was introduced, when the lights show red simultaneously.

This puts traffic on approach roads at a standstill while pedestrians cross, trapping drivers in tailbacks often stretching back to Holborn Viaduct.

Cabbies said the new system had added more than 20 minutes to crosscapital journeys, and effectively cut off one of the last few remaining east-west routes across London following the redesign of Trafalgar Square.

It had also gridlocked a swathe of local roads in central London.

Steve McNamara, of the London Taxi Drivers Association, said: "Before the lights were changed at Procter Street there was never more than a handful of vehicles waiting to cross. By the time it finally goes green motorists absolutely surge through in desperation - there will be an accident soon and some drivers simply run red lights.

"It is absolute chaos and it must be costing London millions of pounds in delays, all for no gain. We all understand the need for pedestrians to be able to cross in safety but whoever thought this up is insane."

When the Evening Standard visited the junction yesterday, traffic moving west on Holborn had between 10 and 16 seconds of green time.

It was then held back on red for between one minute and 20 seconds and one minute and 40 seconds. The phasing changes throughout the day in line with traffic conditions. Transport for London said it had been requested to make the changes at Procter Street by Camden council and that it was obliged to co-operate. But a spokesman for Camden-insisted: "We do not deal with traffic-lights." He refused to give any further explanation.

Kevin Delaney, head of road safety for the Institute of Advanced Motorists, said: "The whole idea that one borough can go off on a frolic of its own and create chaos is a disgrace.

"As soon as the Mayor hears about it he should flex his muscles, show what he is made of and bring Camden to heel. This is a vital east/west route and if it is not working properly, neither can London."

The taxi drivers' appeal to the Mayor comes days after TfL revealed that congestion in central London is now back to levels last seen before the C-charge was introduced in February 2003.

TfL blamed roadworks and "traffic management measures" for the slowdown. But Mr Johnson announced urgent measures to speed up traffic, including instructing TfL to rephase traffic lights in a bid to avoid jams.