Balfour Beatty has implemented an innovative ‘mega tent’ to facilitate bridge renewal at Paddington.
- The 1912 London Street overbridge’s renewal is vital due to its corroded state.
- Challenges include maintaining access amidst construction at a busy railway station.
- A detailed design process and stakeholder negotiation were critical to project approval.
- The project aims to strengthen infrastructure while ensuring passenger safety.
Balfour Beatty, under the aegis of Network Rail, has embarked on renewing the historic 1912 London Street overbridge. The renewal project needed to address the corroded state of the structure to ensure its strength for modern vehicular use. The bridge, situated above platforms 11 and 12 at Paddington station, last saw its steel girders replaced in the 1950s.
The project faced considerable constraints owing to its location. St. Mary’s Hospital sits on one side, and Mace’s construction of the ‘Cube’ building on the other. Additionally, maintaining operational platforms underneath was crucial. According to engineering manager Bob Barker, two essential traffic flows had to be preserved: passenger access from the taxi rank to Praed Street and vehicle access to the hospital.
Negotiating with stakeholders, including the NHS and Westminster City Council, was a multi-year process. Balfour Beatty demonstrated it could maintain crucial access routes without disrupting hospital activities or neighbouring construction. The company’s early involvement helped in crafting the ‘mega tent’ solution while ensuring a full road closure was justified.
The ‘mega tent’ serves multiple functions, including weather protection and material handling. The tent prevents rain from making the Grade II listed platform tiles slippery, similar to an ice rink, enhancing passenger safety. It also houses an overhead crane, necessary due to the site’s spatial constraints, enabling the lifting of beams and girders.
Constructing the ‘mega tent’ involved building supporting legs through air vents onto the Paddington station platforms, avoiding direct support off the bridge. Engineering manager Barker explained the staging involved in moving the structure’s legs to facilitate slab casting and related activities. The tent, functioning as an industrial work environment, maximised efficiency under tight space conditions.
The bridge renewal includes replacing old beams with bespoke 9m steel girders, fabricated offsite. Materials were transported to the site using special tracks and mobile trolleys. Temporary supports, termed raking props, were essential to uphold the train shed arches beneath the bridge during the works.
Advanced monitoring systems ensured the immobility and stability of surrounding structures throughout the project. Post installation of the new beams, the overhead crane has been dismantled, though the mega tent remains to protect ongoing activities beneath.
Looking forward, the project will reincorporate the Grade II listed lean-to structure, merging historical aesthetics with modern safety standards. Past components need updating to meet contemporary regulations before the roadway’s restoration, set for completion by mid-2025.
The Paddington bridge renewal demonstrates innovative approaches to infrastructure challenges, with completion expected by 2025.
