Final piece of the tunnel placed under river

The fourth and final part of the vital river section of the New Tyne Crossing was lowered into place beneath the Tyne today (Tuesday), completing the under-river link of the new vehicle tunnel.

image of final piece of tunnel being placed in river

Project bosses welcomed guests to the construction site of the new tunnel, which will link the A19 between East Howdon and Jarrow, to witness the immersion of the fourth pre-fabricated concrete tunnel unit into a dredged trench in the river bed.

Paul Fenwick, Project Director for the Tyne and Wear Integrated Transport Authority (TWITA), the project promoter, said: “I’m delighted to see this final section of the tunnel being lowered into place. The river section is one of the most technically challenging parts of the New Tyne Crossing project and it is great credit to main contractor Bouygues Travaux Publics and to their principal sub-contractor VolkerStevin Marine that this phase of the works has gone so well.”

Managing Director of Concessionaire TT2, Trevor Jackson, added: “The river works represent the essential part of this project, providing the much-needed connection beneath the Tyne between North and South Tyneside, and completing the dualling of the A19. With the successful immersion of the final unit today we can proudly say we have a new tunnel under the Tyne.

“The project overall is proceeding to programme. We’re about 60% of the way through construction, and remain on target to open the new vehicle tunnel to traffic this time next year.”image of final piece of tunnel being placed in river with project team in foreground

Nicolas Caille, Project Managing Director for Design and Build Contractor, Bouygues Travaux Publics, said: “The flotation and immersion of the tunnel units has gone very well, and today marks the successful completion of this phase of works. We have floated one tunnel unit out of the dry dock at a time, since the beginning of January, for immersion beneath the Tyne. Putting into place this final piece of the puzzle will enable us to complete the river tunnel and link it up to the tunnels that are being built either side of the river.

“The river works have been very challenging and demanding. Everyone involved in this part of the project is delighted with the progress we have made.”

Specialist contractor, VolkerStevin Marine was appointed by Bouygues Travaux Publics to construct the reinforced concrete tunnel segments at Walker Dry Dock and transport them 3km downstream to their final destination.

VolkerStevin Marine’s project manager, Gerrit Smit, said: “We have been very pleased with the way the immersion process has gone. Although the weather was not always favourable, we have completed the works on schedule. The commitment and dedication of everybody involved contributed to this success.”

The river section of the tunnel is made up of four 90 metres long, 15 metres wide and 8.5 metres high concrete units. Despite weighing in at 10,000 tonnes each, the units must be weighted with water through use of internal ballast tanks in order to lower them into position. image of final piece of tunnel being placed in river with project team in foreground

The last unit to be immersed is located adjacent to Howdon Basin, and connects to a transition structure built on the river bank, which will link the river tunnel to the cut-and-cover tunnel beneath the land. Special seals (Gina gaskets) have been used to secure the tunnel units together, and also to secure their connections with the land tunnels.

With all tunnel units now positioned beneath the Tyne, a loading fill and rock armour will be placed above the tunnel, within the river bed, to protect it from potential damage. The internal bulk head walls and ballast tanks will be removed so that by late spring 2010 there will be clear passage from one side of the river to the other.

The new vehicle tunnel is due to open to traffic in February 2011, at which point the existing tunnel will close for major refurbishment. Both tunnels will be operational by the beginning of 2012.