The largest road tunnel in the UK will be built after an £8.3bn plan was approved by the government.
The Lower Thames Crossing would link Tilbury, Essex, and Gravesend in Kent by two tunnels running underneath the River Thames.
National Highways hoped the road would reduce traffic at the Dartford Crossing by 20% and open by 2032.
Jim Dickson, the Labour MP for Dartford, said the decision would "finally deliver a solution to the traffic chaos" faced by motorists.
The 14.5-mile (23km) road would link the A2 and M2 in Kent with the A13 and M25 in Thurrock, with 2.6 miles (4.2km) routed underground.
Tuesday's announcement was 16 years in the making, with the project first mooted in 2009 and more than £800m in taxpayers' money spent on planning since.
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