Advance works for Crossrail at Moorgate in the City of London are nearing completion. A 36 metre-deep shaft (117 feet) has been sunk under Moorhouse, a prestigious new 20-storey office complex.

This draught relief shaft will provide draught ventilation and access to the Crossrail tunnel network.

This highly sophisticated construction project will put in place some of the infrastructure that would be required by Crossrail to operate the cross-London rail link.

As well as the draught relief shaft, the construction includes development of a third of Crossrail's underground ticket hall for Liverpool Street Station, beneath ground level.

Crossrail's senior tunnel design manager, Gordon Torp-Petersen, explained: 'This is a very unusual project. The creation of draught relief shafts is rarely simple, but the fact that this one is being constructed beneath a new office development while it's being constructed gives it an additional complexity.

'It has meant that, as the office building is being fitted out above ground, a deep shaft is being excavated below ground. This means that the contractors are having to focus on building both up and down simultaneously.'

David Fison, Chief Executive of Skanska UK Ltd, commented: 'This project has posed a number of technically complex engineering challenges. The Moorhouse office development is a further example of Skanska's ability to integrate in-house construction disciplines to provide a total solution.

'We are delighted to have worked so closely with Crossrail to successfully deliver this effective and innovative engineering solution for this vital cross London railway.'

The shaft when completed will measure eight metres (26 feet) in diameter and 36 metres (117 feet) deep below second basement level. It is being constructed by Skanska for Moor House Property Developments Ltd as part of its requirement for the new Moorhouse office complex.

Using strategic partnerships such as this (referred to as 'Combined Works'), to develop the infrastructure for the Crossrail project, is fundamental to the development of Crossrail.

Under the terms of the Department of Transport's Safeguarding Direction of October 1991, a proposed railway corridor across London was safeguarded. Any new developments along this route place planning constraints on developers, requiring them to make necessary provision for the proposed rail infrastructure in their plans.

The Moorhouse redevelopment site is located entirely within this safeguarded area.

Gordon Torp-Petersen added: 'This safeguarded area means that no new construction can occur without taking account of the proposed rail route.

'Some people may be confused by these works progressing before Crossrail is given the go-ahead. However, these advanced works are essential for putting in place the infrastructure that would be required for a cross-London rail link. '

Mr Torp-Petersen concluded: 'It makes far more sense to minimise disruption and build the infrastructure as opportunities arise - as we are doing at Moorhouse. This way we can reduce the amount of work that would be required if and when full construction starts.'

The construction of the draught relief shaft and ticket hall space is being progressed throughout the fit-out of the Moorhouse complex, which is expected to be completed in the Autumn of 2004.

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For further information contact Crossrail helpdesk 0845 602 3813 or e-mail helpdesk@crossrail.co.uk

Issued 14 September 2004