The £260M New Tyne Crossing required several different construction methods and needed to overcome some specific technical challenges.
The second vehicle tunnel was built using immersed tube technology in the river section – only the third tunnel in the UK to be built using this method (the others are the Conwy in North Wales, and the Medway in Kent).
The total length of new carriageway was approximately 2.6 km. The tunnel itself made up 1.5km of the total length. A new interchange had to be constructed at the south end of the tunnels within tight spatial constraints, taking into account railway and Metro bridges over the A19 and the proximity of housing.
Gas mains, sewers and water mains crossed the site in several places. In Jarrow, an alternative to the cut-and-cover technique had to be found in two sections to avoid a costly diversion of a gas main and a sewer. The solution was to excavate under the utilities and secure the walls of the tunnel with a sprayed concrete lining. On the north bank of the river, the new tunnel passed over the line of the original bored tunnel with a clearance of only 2.7 metres and special measures had to be taken to ensure the original tunnel did not move.
The refurbishment of the existing tunnel required it to be stripped down to its basic structure and an emergency escape passage installed. Both tunnels were equipped with the UK’s first fixed fire suppression system, making the crossing one of the safest in Europe. The material dredged from the river was used to fill in Tyne Dock to help the Port of Tyne’s redevelopment programme.
During the construction of the New Tyne Crossing, the complex works were effectively managed so that only two weekend temporary closures of the existing Tyne Tunnel were required throughout the entire programme.