THE SECOND of two box-jacking operations for the remodelling of Shortlands Junction near Bromley in Kent, was due to take place over the bank holiday weekend in August.
Main contractor Geoffrey Osbourne, working for network manager Railtrack, was due to carry out the operation, which involves pushing a 80m long, 12m wide concrete box beneath main line tracks on the London to Chatham line.
The new layout will increase capacity at a key pinch point on the rail network by allowing four Eurostar trains an hour to travel between Waterloo International and the Channel Tunnel without being caught behind slow moving freight services (European Foundations Winter 2001).
The reinforced concrete box was built insitu in a cofferdam excavation next to the tracks.
Before the jacking operation could start existing track had to be removed to allow excavation ahead of the box.
'We've got 20,000 tonnes of muck to excavate ahead of it, ' said Geoffrey Osbourne project director Barry Elswood. 'If the excavation moves ahead of the box it will be fairly straightforward but it will be hard dealing with such a large volume of soil over such a narrow face.' Once the box was in position the track had to be relaid in time for trains to begin running on the Tuesday.