The fourth and final part of the vital river section of the New Tyne Crossing was lowered into place beneath the River Tyne yesterday, completing the under-river link of the new vehicle tunnel.
The new tunnel will link the A19 between East Howdon and Jarrow near Newcastle, to witness the immersion of the fourth pre-fabricated concrete tunnel unit into a dredged trench in the river bed.
The river section of the tunnel is made up of four, 90m long, 15m wide and 8.5m high concrete units. Despite weighing in at 10,000t each, the units must be weighted with water through use of internal ballast tanks to lower them into position.
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.
Design and build contractor Bouygues Travaux Publics project managing director Nicolas Caille 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.”
Bouygues Travaux Publics appointed specialist contractor VolkerStevin Marine to construct the reinforced concrete tunnel segments at Walker Dry Dock and transport them 3km downstream to their final destination.
VolkerStevin Marine 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.”
Project promoter Tyne and Wear Integrated Transport Authority (TWITA) project director Paul Fenwick said: “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.”
Concessionaire TT2 managing director Trevor Jackson added: “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.”