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The companies, working together in joint venture as a main works contractor for the UK’s High Speed 2 (HS2) railway project, slid the deck into position near the town in Wendover, Buckinghamshire.

The 450m-long deck was assembled in three stages ranging from 90 metres to 180 metres, with each one pushed out from the north abutment before the next section was attached behind it.

The 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 up to 3,700 tonnes by the time it reached the south abutment on 17 August.

Special pads covered in Teflon were used to minimize friction between the deck and the temporary steel bearings on top of each of the concrete piers.

The deck was pushed slightly uphill to help maintain control, with the finish point around 1.8m higher than the start point.

Now the steelwork is in position, work can start on the concrete that will support the railway using a specially designed travelling formwork. This process is expected to take a year and will be followed by the installation of parapets along the edge of the viaduct.

The Wendover Dean Viaduct is the first major railway bridge in the UK to be built with a ‘double composite’ structure, which uses significantly less concrete and steel than a more traditional design.

The hollow ‘double composite’ structure uses two steel beams sandwiched between two layers of reinforced concrete, instead of using solid, pre-stressed concrete beams to form the spans between the viaduct piers.

Another four viaducts at Small Dean, Westbury, Lower Thorpe and Turweston will all use a similar design but are at an earlier stage of construction.

EKFB is building all five viaducts.