£6bn bored tunnel selected for new Thames crossing

Highways England has laid out its preferred route for a new Lower Thames Crossing featuring a two mile twin bored tunnel between East Tilbury and Gravesham. A tunnel bored beneath the Thames at this location is the only viable alternative because a bridge would present a lot more impact on the local environment, according to route analysis published by Highways England.

Different options for connecting a bored tunnel with the existing motorway network are now out for consultation. There are three different routes for connecting with the M25 north of the River Thames and two variations for new links to the A2 and M2 to the south. Highways England's preferred route would be 15 miles long connecting with the M25 at a new junction near South Ockendon and the start of the M2 at Rochester. Total capital costs are estimated at £4bn to £6bn.

The 'location A' option of a new bridge at Dartford close to the existing twin tunnels and QEII bridge has now been discounted and is not being taken forward for consultation, Highways England says. This option would be cheaper at £3.5bn to £5bn but presents poor value for money. It neither presents a new route, nor opportunities for new housing and job creation and instead would funnel more traffic onto existing roads south of Dartford.

A third location B near Gravesend was dropped from the outline plans following a previous consultation in 2013. Highways England has since been progressing options for the two remaining locations, including road improvements to connect the crossings to the existing motorway network north and south of the river.

To the south the preferred route is now the Eastern Southern Link connecting with the start of the M2 at Rochester. A Western Southern Link connecting with the A2 is included in the consultation. A previous proposal for upgrading the A229 to create a motorway connection with the M20 is not included.

Three different routes are proposed for connecting location C to the M25 either at Junction 29 or Junction 30 or the third preferred option involving a new junction with the motorway near South Ockendon. All three options present similar economic benefits for housing and job creation but with different local impacts.

An immersed tube tunnel has been considered as well as bridge and bored tunnel options between East Tilbury and Gravesham, but this would present more damaging environmental impacts similar to the bridge option, Highways England says. 

Highways England senior project manager, Martin Potts said: “Deciding where the new crossing should go is a vitally important decision, and we’ve been working hard to identify solutions that strike the best balance between improving journeys, getting value for money and managing environmental impact. Our assessments have shown that Location C provides double the economic benefits of Location A as well as a clear alternative route to the Dartford Crossing, reducing congestion and improving resilience of the road network. And by choosing a tunnel rather than a bridge we can minimise the effects of the new road on the environment.

“There are important choices to be made. As well as inviting comments from the public about our recommendations, we have identified three routes for the new road to the north of the river and two routes south of the river. We welcome views on them all."