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Swing Bridges Update

Report from Richard Scott – Galliford Try Site Engineer

The Galliford Try site team mobilised in October 2011.

Mobilisation works included setting up temporary site offices in a compound behind Howdens Joinery on Chestnut Lane.

A satellite compound was also set up at Ocean Bridge, Stonehouse.

Local Business Access

A temporary access road has been constructed through the Avocet industrial estate just off the Cainscross Road (A419) then through Marling School’s former rugby pitch as far as Gasworks Bridge on Chestnut Lane.

The road foundation was constructed from 100% recycled aggregate. Picture 1.

When the existing bridge has been demolished the road will form a diversion that allows public access to businesses south of Gasworks Bridge.

Gasworks Bridge

Work in the canal channel required Flood Defence Consent from the Environment Agency. This was finally issued in November. Picture 2.

Initial excavations revealed Gas, Water and Electricity mains crossing Gasworks Bridge.

These services must be diverted prior to the removal of the existing bridge.

The gas provider has been notified of the findings and Galliford Try is liaising with Wales and West Utilities to agree the exact route for the diversion.

Two temporary bunds and a flume pipe have been constructed upstream of Gasworks Bridge to permit diversion of the Gas and Water pipes.

It is envisaged that these will be installed across the canal prior to Christmas.

Early in the New Year two temporary dams and a flume pipe will be installed close to Gasworks Bridge. The electricity cable can then be diverted and the bridge demolition can begin.

Ocean Bridge

Temporary dams were constructed each side of the works during November. This created a dry area for works to be carried out.

Flood prevention & ecology considerations

A temporary flume pipe between the dams maintains the flow along the canal channel. This prevents flooding upstream of the works. It also benefits the local ecology by allowing wildlife to migrate.

The existing Ocean Bridge was removed and sent to a metal recycling facility.

Demolition of the existing abutments and road approaches was carried out along with the bulk dig for the new structure.

The original masonry was retained where possible.



Parts of the former swing bridge, including the old pintle bearing, were unearthed. See picture 3.

Pedestrian access ensured

The upstream temporary dam includes a footway enabling the public to cross the canal whilst the new bridge is out of use. Picture 4.

Asbestos action taken

Cement bonded asbestos was discovered during the excavation. This required special measures to be taken to protect the public & site personnel and to ensure the asbestos was disposed of correctly.