New Tyne Tunnel construction reaches halfway mark

Oct 29 2009 by Tony Henderson, The Journal

THE building of the new Tyne Tunnel has passed a major milestone. Land-based excavation work which began a year ago has now been virtually completed, meaning the construction of the crossing has reached the halfway mark.

The cut and cover operation has involved digging trenches of up to almost 30 metres deep at Jarrow, where the length of the excavated tunnel section is 800 metres on the south side of the river, and East Howdon on the north, where the section runs for 300 metres.

These will accommodate the land sections of the crossing and have involved building the concrete tunnel walls, laying 80% of the floor slabs and building 37% of the roof slabs.

Once complete, the land tunnel sections will be covered with excavated material which has been stored at sites in South Shields and Wardley in Gateshead and on the north bank construction site itself.

When excavation work was at its peak there were 500 lorry trips a day on the south side.

On the north bank the amount of material excavated for the tunnel length and the new toll plaza is 340,000 tonnes, with 400,000 tonnes being dug up on the south side.

Work is currently under way on the remaining 4% of land excavations required for the two short sections in Jarrow. These sections use a specialised technique involving concrete spraying of excavated areas to allow tunnelling beneath utilities such as sewers.

The only section on the north bank which has not been a cut and cover job has been the construction of a short section of the new crossing which passes over the top of the existing tunnel.

Sensors were used in the existing tunnel to monitor any ground movement during this operation.

Trevor Jackson, managing director of TT2, which is part funding the project and will manage, operate and maintain the two vehicle, pedestrian and cycle tunnels for 30 years, said: “Construction work is going well and we’re delighted with the progress we’re making across the site.