As part of the construction of 25 Bank Street and the re-development of the Heron Quays Docklands Light Rail station, CWC and its contractors developed a unique methodology for building both the 8-storey air-rights building over the railway, and simultaneously re-building the 2-level platforms and concourse below. All while the railway remained in operation.

Our solution was to erect a temporary assembly platform and two lines of runway beams running parallel to the railway over the entire viaduct. This was done during engineering hours.

The 9.2 metre trusses were delivered by barge which was moored in the dock adjacent to the site. The trusses were lifted onto the runway beams at the south end of the building, over the assembly platform, in just one weekend. Next, we "launched" the trusses forward by jacking one truss forward, erecting steel infill and decking, then jacking the complete assembly forward again. This was repeated until all trusses and infill structures were in position. All while trains were passing underneath.

Upon completion of the "launch" and infill phase, the level 4 deck was concreted to provide protection for the railway below, and a further 5 floors of steel and deck erected over the railway during daytime. Only the two end bays were erected at night during engineering hours.

When the steel frame and metal deck were complete, including the large level 8-9 trusses, the load was transferred from the lower level 3-4 trusses to the level 8-9 trusses, as the structure is designed to hang from level 8. The floors between levels 5 and 9 were then concreted in sequence. The lower level 4 trusses were accessible, to fit services and fire protection, by a carefully designed hanging temporary deck which was fitted during engineering hours. The system allowed all mechanical and electrical services above the station platform to be fitted, and subsequently the suspended stainless steel soffit was progressively installed as the scaffold and deck was struck. This allowed maximum use of dayshift hours, whilst avoiding or minimising the impact to the railway.

The whole project was completed with no train stoppages other than planned DLR track maintenance.