Structural steel fabrication and installation on the Thameslink Programme
Steel fabricators Bourne Group had a long relationship with the Thameslink Programme as they were appointed the structural steel contractor at Farringdon station, Blackfriars station and London Bridge station.
The structural steel work at Blackfriars included:
- The temporary, covered passenger staircases and access routes.
- The main station building’s façade.
The Blackfriars challenge
Bourne Group provided structural steel work for both the main station in the north and the new south bank station either side of the River Thames.
During the early construction phase, Bourne Group supplied the temporary, covered steel walkways, staircases and corridors to assist with the diverted passenger flows. It was challenging right from the beginning because the work site was not only near the live railway but also on a bridge, over a busy road and a tidal river.
Elsewhere, steel work was key to the main station which comprised of several functional spaces. These included a retail area, an escalator building, a common entrance area with a curved and a fully-glazed feature façade which was supported by steel bow-string trusses.
The steel work at the south bank station was more architectural. For example, the ‘flying staircases’ have now support columns and are purely attached to the old, existing structure. It wasn’t easy to attach major new extensions to a pre-Victorian structure and there were often unexpected problems due to weaknesses or wear. The south bank station also has a pavilion building, a west and east entrance and a glazed, steel, lift-shaft structure.
The temporary work structures installed by Bourne Group were on the project’s critical path and were an essential part of the Blackfriars reconstruction programme.
A lesson learned at Blackfriars station – Ensure a good alignment of steel work and cladding contracts
The project involved large areas of fully glazed façade and so the cladding contractor had a higher work package value than the steel work. For this reason, the façade contract led the steel work contract. This caused problems for the structural steel team as in reality, their work would always be installed first.
The steel supplier did not have information at the beginning that they needed, and this managerial structure went against the natural flow of the project. This caused many problems and delays and so an important lesson learnt for Bourne Group was that they shouldn’t subcontract to cladding contractors in future.