The two 14.5m (23km) road tunnels under the River Thames, connecting Kent, Thurrock and Essex from the A2/M2 to the M25 motorways, have been green-lighted by UK Secretary of State for Transport Heidi Alexander.

Major construction and tunnel work is scheduled for 2028, almost six years after the application was received by the Planning Inspectorate. However,  in Essex, ground investigations are being carried out to give a better understanding of soil, rock and ground water to help the detailed design of the foundations and structures needed to build the route.

Shaun Pidcock, Delivery Director for the Lower Thames Crossing, at National Highways , which manages England's strategic road network, said: "There's now real progress to be seen, as we start getting the area ready for the new road and tunnel to be built. Our low-carbon approach to construction means the Lower Thames Crossing will be Britain's greenest road and create local jobs and new skills."

Prior construction work will be carried out to protect the area's utility supplies, heritage, and wildlife, with around 1000haof new habitat created. And towards the end of this year gas, water, electricity and telecoms lines will be rerouted.

The project's first work compounds are being set up near East Tilbury in Thurrock, and at Thong near Gravesend. They will contain facilities for workers and storage for machinery, equipment and materials.

Six hydrogen generators are already at work on one of the compounds alongside a new electric drilling rig and diggers. The project recently bought the largest ever volume of low-carbon hydrogen for a construction scheme.

The Lower Thames Crossing aims to tackle congestion at the Dartford Crossing by almost doubling road capacity across the river east of London.