The Princes Risborough to Aylesbury (PRA) Realignment Team has completed the deck pour for the Princes Risborough to Aylesbury (PRA) Realignment Overbridge in Aylesbury, a milestone which the construction team had just one shot at.
Requiring 270m3 of low-carbon concrete, delivered by two boom pumps, the steel deck was filled within a nine-hour window. A special logistics set up was in place at the site, with an exclusion zone and one way system to ensure efficient and safe delivery of the concrete.
The overbridge deck, which is 100m long sits on a piled foundation, including four huge piles which will form the piers of the bridge. At 2.4m diameter and 58m deep these piles are the biggest in the Main Works section of the project.
Agent, Gemma Teale, is proud of the team, saying: “This was a really important pour for us, it is a milestone, a crucial part of our scope, and because of the nature of the structure, a pour where ‘right first time’ is even more important than ever, as anything that went wrong would be incredibly difficult to rectify. The team, including our supply chain partners Octavius Infrastructure, worked well together under pressure, and we are really pleased to have such a key part of the project complete.”
The PRA Realignment Overbridge is part of a wider package of works to realign a section of the Princes Risborough to Aylesbury to allow HS2 to pass underneath it through the Aylesbury South Cutting. This includes a dual carriageway road underpass, the diversion of Stoke Brook into a new culvert, three high voltage electric diversions and two high pressure water diversions, 1.8km of railway embankment all in a tightly constrained location, and next to a live railway.
Project Director, Ignacio Chicharro, commented, “The PRA programme is complex and has been challenging, but I’m pleased with the progress the team has made to date, and I’d like to congratulate the team on achieving this milestone. To be in a position where we’ve poured the deck puts us in good stead for the remaining works which will be completed this year.”
The realignment, which is circa. 20m from the original line at its furthest point, is integral to keeping the Network Rail line open as HS2 passes through, and the team have to work carefully in line with Network Rail regulations to construct it around regular passenger and freight services.