HS2 engineers have completed the final touches on a major viaduct that will eventually carry new high-speed trains across a floodplain of the River Great Ouse near Brackley.
The Westbury viaduct, which is set low in the landscape to the east of the town, measures in at 320 metres in length, and was built using a ‘double composite’ approach inspired by recent viaducts on the French TGV network, which uses less carbon-intensive concrete and steel than a more traditional design.
Utilising a layer of reinforced concrete both above and below the structure’s steel beams; this approach eliminates the need for both a purely concrete span or a steel beam supporting a concrete deck, creating a more efficient box-beam in the process.
All steel beams were assembled n the north abutment before being slid into place between March and October 2024, and weigh 2,695 tonnes. During the slide, special pads were used in order to minimise friction between the deck and temporary steel bearings on top of each of the concrete piers.
Once the beams were in place, a travelling formwork was used to cast the concrete deck. Completed in 42-metre-long sections, the formwork was pulled forward each time to allow the next section to be cast and then, with the deck complete, prefabricated parapets were then lifted into position along the edges and secured into place.
HS2 Ltd’s Senior Project Manager, Paul Cooper said:It’s been amazing to watch Westbury viaduct come together over the last few years and I’d like to thank everyone involved in getting this incredible structure over the finishing line.
This section of the railway is now really starting to come together, and with the viaduct complete, our focus will turn to completing the earthworks and other nearby structures.
The largest viaduct in the Brackley area; Westbury is one of fifteen being built by HS2 Ltd’s main works contractor, EKFB, who are responsible for the central section of the HS2 project. The contractor is made up of Eiffage, Kier, Ferrovial Construction and BAM Nuttall.
With construction now finalised, the hardstanding surface beneath the viaduct, which was used to support to heavy equipment, will be removed in order to allow landscaping to be completed.
Elsewhere, progress is continuing on nearby structures such as the Turweston green bridge, which was completed in April, as well as the realignment of the A43, which was completed in July.
The last few months has also seen progress made at HS2’s other major viaducts, including the key structures that cross the M42 and M6 outside Birmingham and the viaducts taking the railway into the city’s new Curzon Street.
