HS2 completes 320m-long Westbury viaduct

Engineers on the HS2 project have finished the 320‑metre‑long Westbury viaduct, which will carry high‑speed trains across the floodplain of the River Great Ouse near Brackley. The viaduct, the longest in the Brackley area, was constructed using a double‑composite design inspired by French TGV viaducts. This method places reinforced concrete layers above and below a steel beam, creating a more efficient box‑beam that uses less carbon‑intensive concrete and steel than a conventional design. The steel beams, weighing 2,695 tonnes, were assembled on the north abutment and slid into place between March and October 2024. Special non‑stick pads reduced friction during the slide, and a travelling formwork cast the concrete deck in 42‑metre sections. Prefabricated parapets were then lifted and secured.

The viaduct is one of fifteen structures built by EKFB, the main works contractor for the central section of HS2, which comprises Eiffage, Kier, Ferrovial Construction and BAM Nuttall. With the viaduct complete, the hardstanding surface beneath it will be removed and landscaping finished. Nearby progress includes the Turweston green bridge, completed in April, and the realignment of the A43, finished in July.

Senior Project Manager Paul Cooper noted that the viaduct’s completion marks a key step toward finishing earthworks and other nearby structures. EKFB Project Sub Agent Arman Yarali highlighted the double‑composite design’s lighter, more efficient structure and its role in demonstrating EKFB’s capacity for complex, sustainable engineering solutions. The project contributes to HS2’s overall programme of more than 500 bridging structures, ranging from small road bridges to the record‑breaking Colne Valley Viaduct.