Two major tunnels could be built across London in a bid to ease congestion on the roads.
One could run from the A40 at Park Royal in west London to the A12 at Hackney Wick in east London, known as the Northern Cross City Corridor.
The other could potentially stretch west to east from the A4 in Chiswick to the A13 in Beckton.
Major Boris Johnson claims the projects could reduce congestion in the centre of the capital by up to 20%.
He announced the plans as part of a wider roads strategy, including devolution of Vehicle Excise Duty and increased management of freight.
An orbital tunnel is another option being considered, along with a number of smaller tunnels and so-called flyunders.
With London's population expected to hit 10 million by 2030, up from 8.6 million at present, Mr Johnson says action is needed to ensure the city can cope. He warns congestion in the centre could increase by 60% over the same period unless his plans are implemented.
The Northern Cross City Corridor could be open by the mid to late 2030s, funded through toll charges.
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