Work is continuing on a new tunnel crossing under the River Tyne. The tunnel - designed for vehicles - will connect East Howdon and Jarrow and is due to open in December 2010. This aerial image shows the route it will take.
The section of the tunnel that will pass under the river will be formed by four huge concrete sections, called caissons, seen here on the dry dock in Wallsend. Each one is approximately 90m long, 15m wide and 8.5m high.
A closer view of one of the caissons. A deep trench will be made in the bed of the River Tyne and these prefabricated concrete sections will be placed into it to form the tunnel.
The north section of the tunnel is being constructed using a process known as 'cut and cover'. Parallel concrete walls are constructed underground and the area between them is excavated in stages. Temporary struts are put in for support, as above.
Once the supports are in place, base and roof slabs can be added to complete the structure and the roof can be covered with soil.
The cut and cover technique is also being used for much of the south side of the tunnel - although two short sections will require traditional underground boring techniques.
There are special transition sections at the two points where the tunnel enters the river. These allow the river section of the tunnel to be connected to the cut and cover structures on either side.
Work is also taking place on the road junction at the south entrance to the tunnel, including the construction of a new bridge. For more information about the new tunnel and how it is being constructed visit www.newtynecrossing.info
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