A bridge too complicated

This was not the first time that Bridge GE19 - to give it its official title - has caused trouble. At Christmas the demolition of the old bridge forced the closure of Liverpool Street station. The work overran due to Network Rail not finishing separate engineering work on time. The station, which closed on 23 December, did not reopen until 2 January, nine days later.

The bridge, which crosses the mainline tracks on the approach to the station, was originally constructed to allow trains from the Great Eastern Line to enter Bishopsgate Goods Yard. It was demolished as part of the expansion and improvement of the East London line. The delay was caused by the complexity of removing the old structure.

When the new bridge was first being installed, Transport for London said: "Installation is a huge engineering operation which involves inching it slowly into place with the same kind of wheels used to manoeuvre shuttles to their launch pads."

The bridge is 84 metres long, 10 metres high, 10 metres wide and weighs 812 tonnes. It was made of British Corus steel in Chepstow, south Wales, brought to London in sections by road and assembled on site over four months.