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Greenford Flyover
 

Description of Works
Working closely with Transport for London (TfL), FM Conway’s asset management team worked on the delivery of a technically challenging flyover renewal scheme on one of London’s main strategic roads, the A40.

As part of the company’s London Highways Alliance Contract (LoHAC) with TfL and its joint venture partner AECOM, the brief for the FM Conway team was to replace 24 bearings on the ageing Greenford Flyover.

Challenges and Solutions

The Greenford Flyover exists on a primary route into the Capital, therefore is highly congested. 

Ismet Sakajani, Contracts Manager at FM Conway, explains:
“Built in the 1960s, the structure had decayed over many years and was in critical need of repairs. The challenge for us was to keep it open while undertaking these works”.

The solution chosen by the team has not only allowed the flyover to remain open, but also brought forward TfL’s targeted completion date for the project. Using the heavy-duty temporary props, the team were able to lift the bridge deck up to 2.5mm off its existing bearings, working with the wider CONWAY AECOM team to carefully monitor the loadings on the bridge while the old bearings were replaced with the new.

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It’s a delicate process which requires constant dialogue between the different team members. By using modern technologies, we’ve been able to keep the flyover open to drivers and are on schedule to complete the works in early April, four weeks ahead of TfL’s original completion date.

Ismet Sakajani - Contracts Manager at FM Conway
Delivering Innovation

Ismet explained the process: “The temporary props need a solid foundation on which to sit, so before we began the replacement work we excavated down to the flyover’s pile caps – down to a depth of three metres in some places. We then put the steel props in place, fixing them to the bridge soffit. The next stage was to lift the bridge deck using the hydraulic power and lock the props in place.”

The team replaced each bearing in turn to ensure the stability of the flyover for traffic, using hydro demolition technology to expose the footings of the old bearings. Once removed, a new bearing is then drilled into the existing socket and secured with concrete and a final layer of grout to fill any air pockets between the bearing and the concrete.