A "countdown" timer for pedestrians, which will tell them how long they have to cross the road, has been unveiled in south London.
The first such digital timer to be tested has been placed on Blackfriars Road opposite Southwark Tube station.
The countdown begins after the green man appears and until it turns red.
During the 18-month trial, costing £750,000, eight busy junctions in London will get the timers, including Oxford Circus and the West End.
Charity Living Streets said the scheme was an "expensive way to increase traffic at the expense of pedestrians".
Confusion over symbols
The trial comes after a Transport for London (TfL) study found that about half of the pedestrians crossed junctions even after the red man had appeared.
The study also found that at least 60% of pedestrians did not know that the road can safely be crossed even during the blackout period between the green and red man symbol.
London Mayor Boris Johnson said: "This technology already works well in other cities around the world and bringing it to London's streets is just one of the ways we are continuing to improve the experience of travelling around the capital.
"We hope this will make London safer for all concerned and smooth the flow of traffic to help keep London and its inhabitants moving."
TfL found that about 20% of all fatal and serious pedestrian injuries in London occurred at pedestrian crossings.
Tony Armstrong from Living Streets said: "We really fear that they are being introduced in London in order to shave off the time that pedestrians have to cross the road and increase the flow of motor traffic.
"In trials that were carried out before these countdown crossings were put in, lots of pedestrians said they were disappointed with the results, particularly those with disabilities and elderly people found it a real struggle to get across the road in time."