Crossrail contractor Costain Skanska Joint Venture (JV) has completed the construction of the diaphragm walls and columns that will support the roof of the new Crossrail Paddington Station.

Work started on the project in April 2012 to construct a 40 metre deep reinforced concrete wall around the perimeter of the new station. Crossrail, Costain Skanska JV and subcontractor Cementation Skanska worked round the clock for 11 months to put in place the 165 individual diaphragm wall panels and 51 plunge columns to form a box 265 metres long and 22.5 metres wide.

The completed walls, which are made up of 165 rectangular panels measuring 3.3 metres in length, 1.2 metres in width and 40 metres deep, required over 64,000 tonnes of concrete and 5,000 tonnes of steel in their construction. The excavation of the panels saw over 53,000 tonnes of London clay removed.

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The project wasn't without its challenges, particularly due to the restricted space the site team had to work in. The tunnel boring machines that are being used to construct the new train tunnels had to pass through the walls of the station as part of their journey between Royal Oak and Farringdon, which meant the team had to meet tight deadlines. Each boring machine measures 150 metres long - roughly equivalent to 14 London buses placed end to end - and weighs around 1,000 tonnes.

"One of the biggest challenges we encountered was completing the required minimum proportion of wall ahead of the approaching tunnel boring machines. A failure to get this done on time would have meant serious delays elsewhere on the programme," said Rupert Shingleton, Costain's Project Director.

After the outer walls were completed, the team then put in place 60 metres by 1.8 metres diameter central columns to support to the station roof and provide ground anchorage to the box.

The new Crossrail Paddington Station will be 260 metres long, 30 metres wide and 30 metres deep and will provide step free access to platform level along with an interchange with National Rail and London Underground. Eastbourne Terrace, a main road that serves Paddington Station, will be reopened once the work has finished, with a target date set for February 2014.

(CD)