The challenge
We worked with client Dragados Sisk JV and multiple project stakeholders from Crossrail, Transport for London, Docklands Light Railway, London Underground and Newham Council to help manage the impact of Crossrail eastern tunnelling on the busy flyover.
We designed and delivered a complex lifting system to mitigate the tunnelling works underneath by raising the flyover. A jacking and a structural monitoring system was installed prior to the tunnel-boring machine passing under the viaduct, to protect the flyover and monitor any structural movement.
Our solution
We first baseline monitored the flyover for 12 months to understand structural movement.
We designed a live viaduct jacking scheme across 11 piers to control inter-pier settlements to within 2mm. This was monitored and controlled to accommodate any movements of the piers.
The bridge, the pillars and track were then ‘floated’ on hydraulic jacks at each bearing location between and including the piers, across 11 piers in total. The permanent bearings were then removed and temporary joints were designed using structural steel and hydraulics.
The jacks were linked and controlled centrally to control the vertical and horizontal movement of the deck. The measurement of the viaduct’s position and performance was achieved through the combination of bespoke monitoring devices supported by software to provide accuracies of greater than 0.3mm.
Data from the sensors on-site was presented 24/7 via our Insite portal, ensuring the project team knew the behaviour of the bridge at any time.
The project successfully floated the flyover across the 11 piers for 18 months, with any structural movement monitored and maintained to tolerance.
The Crossrail tunnelling project was able to continue as planned, keeping open the flyover and safely managing the planned works.
