London mayor Boris Johnson will pledge to deliver a new tunnel for road traffic under the Thames in the east of the capital within the next 10 years.
The proposed tunnel, between the Greenwich peninsula and Silvertown in the Royal Docks, will have a capacity of 2,400 vehicles an hour in each direction, and will relieve pressure on existing tunnels at Blackwall and Rotherhithe to the west.
Speaking to London government leaders this evening, Johnson will describe the tunnel as part of a package of transport investment to support the capital's growth.
He will also say that TfL is pushing ahead with preparations for an extension to the Northern Line of the London Underground to Battersea, which has not previously been served by the Tube.
The Mayor will also promise that a new ferry crossing between Beckton and Thamesmead at Gallions Reach will be open for traffic by 2017, creating a further transport link in east London.
However experts cautioned that while the Blackwall tunnel needed relieving, the key issue would be funding - especially given that introducing tolls to existing crossings would be politically toxic in an election year.
"The big question is how is this to be funded," said deputy director of the Demos Centre For London, Rob Whitehead. "Has the Department of Transport committed money? It was mentioned in the Autumn statement but not in a conclusive way."
"Boris's record of trying to reduce costs on capital projects by levering in private sector investment is patchy," he added. "With both 'Boris bikes' and the Greenwich cable car this proved harder than expected."
In his speech, Boris will say:
"When I look at London, I see a city of incredible potential and tonight I will make the case for a huge new phase of investment in the capital, including a major new river crossing east of Tower Bridge.
"We are in the right time zone, speak the right language and have the young, skilled population to continue to attract investment from the world's greatest businesses. This is not a time for London to falter it is a time for London to flourish."
Transport for London will begin preliminary consultation work on the Silvertown Tunnel in February, said the mayor.
The Silvertown Link has been under discussion since at least 2005 as one possible solution to traffic congestion in the Blackwall and Rotherhithe tunnels.
TFL has previously said that new crossings would "support ambitious plans to create new communities, job opportunities and housing".
Both the Blackwall and Rotherhithe crossings have been in operation for more than 100 years, and are not designed for modern traffic.
Darren Johnson, a Green Party member of the London Assembly, said: "The London mayor can't claim that air pollution or climate change are a priority whilst proposing to build a traffic-generating road like this Silvertown Tunnel.
"This tunnel is a straightforward attempt to double capacity around the Blackwall Tunnel and will generate extra traffic all over east London."
However the move was welcomed by AA president Edmund King, who said: "The Thames is a barrier to mobility, employment and enterprise in east London. The Seine in Paris has almost twice as many river crossings as we have over or under the Thames.
"This proposed new tunnel is most welcome and could do much to alleviate congestion and emissions around the Blackwall Tunnel."
The Rotherhithe tunnel was constructed with sharp, nearly right-angled bends designed in part to stop horses seeing daylight at the end of the tunnel and bolting for the exits.