Work has begun on a £50m cable car project to link two Olympic venues on opposite sides of the River Thames.
Digging for the foundations of the two new stations in the Royal Victoria Dock and on the Greenwich Peninsula began on Thursday.
Once finished, the cable cars will run 50m (164ft) above the river carrying up to 2,500 people an hour.
It will connect the O2 arena in North Greenwich to the Excel exhibition centre at the Royal Victoria Dock.
The North Station in the Royal Victoria Dock is in east London while the South Station in Greenwich is in south-east London.
A Transport for London (TfL) spokeswoman said completing the project by next summer was an "aspiration", but trying to get it up and running for the Games would be "challenging" and was never a plan.
She added that the cable car project was not a part of TfL's Olympic transport strategy and it was not essential for the Games.
TfL is providing the upfront costs for the project.
Originally the project was to be privately funded and estimated to cost £25m, but earlier this year TfL said it would fund the project to ensure its "quick delivery".
The cable car will provide a "much-needed river crossing" and a "bird's eye view" of the capital, London Mayor Boris Johnson said.
But John Biggs, Labour member of the London Assembly, criticised the scheme saying it was "no substitute" for a bridge across the Thames.
Caroline Pidgeon, the Liberal Democrat leader on the assembly, has also criticised the doubling of its projected cost.
A consortium, led by Mace, is carrying out the building work and will later run the cable cars.