Tunnel Breakthrough

There was light at the end of the new Tyne vehicle tunnel today (Tuesday) as design and build contractor, Bouygues Travaux Publics, broke through the concrete wall at the end of the first section of Sprayed Concrete Lining (SCL) tunnel in Jarrow.

image of new tunnel breakthroughThe new vehicle tunnel comprises two short sections of SCL, equating to approximately 4% of the land tunnel excavations (32 metres and 40 metres 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.

Colin Blythman said: “I’m very pleased to have been given the opportunity to view the building of the new Tyne Tunnel.  It’s an impressive construction, completely different from the first tunnel in which I was involved some 40 years ago.  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.”

Cllr Tom Hanson, Vice Chair of TWITA, said: “The New Tyne Crossing is a project of 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. Today marks another project milestone and a further step towards the completion of the new vehicle tunnel.”

Trevor Jackson, Managing Director of TT2 said: “This marks a breakthrough for the project. The SCL sections may be short in terms of the overall length of the crossing, but that in itself represents a challenge. 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.”

Nicolas Caille, Project Managing Director for Bouygues Travaux Publics, 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.”image of new tunnel work inside the tunnel

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.