Costain : Joint Venture Ahead Of Schedule

9 April 2014

The Costain Skanska joint venture (CSJV) working on Crossrail contract C360, the Eleanor Street and Mile End Park Shafts in the East End, have successfully completed Adit IE1 ahead of schedule.

It is one of a series of adits - horizontal tunnels driven between shafts - that will connect from the shaft to the Crossrail eastbound and westbound rail tunnels under London.

The area in which the work was carried out is known as the Bow Triangle, whose sides are bounded by a London Underground District Line viaduct and two railway lines, making for complications for the jv team constructing the new adit.

CSJV Project Director, Graham Sugrue, said Adit IE1 had not only beaten the planned timetable for completion, but had done so with zero accidents or injuries.

The team working on C360 had achieved tunnelling rates of up to 1m per shift, double the planned 0.5m calculated for a shift, he added.

Although that rate of progress may sound slow, there were several factors at work, said Graham.

"We don't have a traditional tunnel boring machine, we're excavating using a backhoe excavator." Additionally, unlike much of London, the area around Mile End is not largely composed of the easily-carved London clay, but multiple bands of varying materials, which made work much more complex, he said.

"This was by no means an easy adit to construct, a nominal 7-metre diameter in difficult ground conditions and directly below the live London Underground viaduct with no impact at all.

"The strict Section 61 noise limits were constantly monitored to ensure adherence. Extensive efforts from the team ensured that we minimised deliveries and that our muck-away activities took place outside the morning and afternoon school runs, which all contributed towards the success of completing this adit."

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