The deck, which stretches for 450m, was assembled in three stages, ranging from 90m to 180m, with each one pushed out from the north abutment before the next section was bolted on behind it.
This painstaking process meant that the weight of the deck increased with each push, up from an initial 590 tonnes at the start of work in January – to 3,700 tonnes by the time it reached the south abutment on Saturday.
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During the slide, special pads covered in Teflon were used to minimise friction between the deck and the temporary steel bearings on top of the concrete piers.
To help maintain control, the deck – which weighs the same as 264 double-decker buses – was pushed slightly uphill, with the finish point approximately 1.8m higher than the start point.
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With the steelwork now in position, engineers will spend two months lowering the deck 60cm onto the permanent bearings in preparation for its concrete deck.
HS2’s head of delivery, Nicola Henderson-Reid said: “It’s been fascinating to watch the deck slowly inch into position, and we now look forward to the next stage of the project – lowering the deck into final position and completing the complex concrete work that will support the new railway.”
Wendover Dean Viaduct design
The viaduct is the first major railway bridge in the UK to be built with a ‘double composite’ structure, which uses significantly less carbon-intensive concrete and steel than a more traditional design.
Instead of using solid pre-stressed concrete beams to form the spans between the viaduct piers, the hollow ‘double composite’ structure uses two steel beams sandwiched between two layers of reinforced concrete to create a more efficient super strong span.
A similar approach is also being used at Small Dean, Westbury, Lower Thorpe and Turweston, which are all at an earlier stage of construction.
All five viaducts are being built by HS2’s main works contractor, EKFB – a team made up of Eiffage, Kier, Ferrovial Construction and BAM Nuttall – with the manufacture and installation of the beams being led by specialists at Eiffage Metal.
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