Design and build contractor Bouygues Travaux Publics today broke through the concrete wall at the end of the first section of Sprayed Concrete Lining (SCL) tunnel for the new Tyne vehicle tunnel project.
The new vehicle tunnel comprises two short sections of SCL, equating to approximately 4% of the land tunnel excavations (32m and 40m long). SCL techniques have been utilised in two locations in Jarrow in order to avoid major utility diversions.
Representatives from the New Tyne Crossing’s project promoter, the Tyne and Wear Integrated Transport Authority (TWITA), Concessionaire TT2, and design and build contractor Bouygues Travaux Publics visited site today to watch the breakthrough of the underground wall.
They were joined by Colin Blythman, who was part of the workforce responsible for building the existing Tyne vehicle Tunnel, as a Senior Civil Engineer with the first tunnel’s consultant engineering firm, Mott Hay and Anderson.
“This is a very challenging and technically specialised part of the project. I’m delighted with the progress we’re making.”
Nicolas Caille, Bouygues Travaux Publics
Colin Blythman said: “It’s an impressive construction. It will be a significant addition to the existing, nationally known, Tyne crossings. I look forward to seeing the completion of the river crossing phase, which I understand will be the next major project milestone.”
TWITA vice chair Cllr Tom Hanson said the New Tyne Crossing has international significance. “Its complexity has demanded the highest levels of skill, diligence and expertise from Bouygues and its contractors, and I pay tribute to their work to date,” he said. “Today marks another project milestone and a further step towards the completion of the new vehicle tunnel.”
TT2 managing director Trevor Jackson said: “Finishing this first section of SCL tunnel means we now have a tunnel all the way from the riverside in Jarrow to beyond Chaytor Street. Local people can really start to look forward to the building site disappearing and the new crossing opening up.”
Bouygues Travaux Publics project managing director Nicolas Caille said: “This is a very challenging and technically specialised part of the project. I’m delighted with the progress we’re making here. By using this approach we have been able to avoid the disruption of serious utility diversions, including a major gas main that runs across the site.”
The SCL sections use a technique to mechanically excavate the tunnel beneath the ground and reinforce the excavation at the same time, using sprayed concrete. The majority of land tunnel however is being built using a technique known as “cut and cover”, which involves excavating a deep trench, constructing the tunnel at the bottom of the excavation, and then backfilling.
All the cut and cover excavations were completed in October 2009, and floor and roof slabs are currently being built at the bottom of the trench.
The sections of cut and cover tunnel and SCL are separated by temporary underground concrete walls. Structural work on the first SCL tunnel, located in Jarrow’s Riverside Park, is now complete, enabling the final wall separating the SCL tunnel from the rest of the excavation to be demolished.