Prater - London Bridge Station
Client - Network Rail
Main Contractor - Costain
Trade Contractor - Prater (building envelope)
Sub-Contractor - Severfield (structural steelwork)
Supplier - Bailey (specialist anodised aluminium supplier)
The team's objective was to create a collaborative relationship to deliver the design, supply and installation of the complete building envelope package using innovative solutions, from the pre-cast concrete platforms to the roof canopies and associated high level glazing.
Work at London Bridge had to be undertaken in stages, starting at the South side and by taking existing tracks out of operation, demolishing them and creating a new concourse.
Architect and engineering design teams supplied Costain, Prater and Severfield with a 3D model, which the team used to undertake exercises to ensure that it delivers on time, turning to offsite solutions for speed of construction.
Taking a significant leap forward in terms of industry capability, the 6km of platform was segmented into individual cassettes or modules, of which there were 1,110. Every cassette is unique, reflecting the geometry of the twisting and sloping of the platform canopy. Materials used were the same as for a traditional build however; the original proposed structure adapted to allow for the offsite design and ensure the structure was stable.
An offsite manufacturing facility was set-up for collaborative working. Within this facility, Severfield manufactured the steelwork and Prater worked on the roof cassettes which included the M&E interfaces, such as lighting, PA equipment, PIR sensors and security cameras and associated cabling. This work also included the anodised aluminium elements supplied by Bailey. The cassettes were set into adjustable transport frames so the team could access the underneath sections.
Completed at the offsite factory and delivered to site, the team was responsible for:
• Construction and installation of pre cast concrete platform sections.
• Structural steel framework comprising columns and 'Y' arms bolted to spine beams ready for erection on site.
• Unitised roof canopy cassettes, aluminium clad with aluminium standing seam roofing and glazed rooflights.
A landmark decision was made to invest in and build a full-scale constructability prototype in North Yorkshire of a 56m long platform section from London Bridge. Constructing, disassembling and re-constructing the prototype helped identify any issues before getting to site - helping to avoid any unnecessary delays. This process was the first of its kind in the UK and has proven invaluable to the project's successful delivery so far.