HS2 engineers complete Coleshill viaduct milestone, advancing digital construction delivery across Britain’s high-speed rail network.
Engineers delivering HS2 have completed deck assembly for four parallel viaducts near Coleshill, Warwickshire, marking progress on the Delta Junction, a complex rail infrastructure interchange east of Birmingham.
More than 1,000 precast concrete segments have now been installed to create viaduct decks crossing the B4114 Birmingham Road and the River Cole floodplain. The completed structures support the southern section of Delta Junction, enabling high-speed rail lines to diverge while passing between the M6 and M42 corridors.
The interchange mirrors major motorway junction engineering, combining viaducts, flyovers and underpasses to carry HS2 over roads, railways and floodplains. Two wider spans will carry four-track high-speed services, while two narrower viaducts will serve routes connecting Birmingham Curzon Street station.
Caroline Warrington, HS2 Ltd’s Head of Delivery, said: “HS2 will transform journeys between our two largest cities, while freeing up space on the existing West Coast Main Line for more freight and local services.
“The Delta forms a key part of the project and it’s great to see it starting to come together. I’d like to thank everyone involved in the Coleshill viaducts and look forward to seeing more progress in the year ahead, as the focus turns to completing the robust kerbs and parapets.”
Off-site manufacturing and precast concrete segment installation
The Coleshill East and West viaducts, stretching a combined 2.4km, are being delivered by HS2’s Midlands contractor, Balfour Beatty VINCI (BBV). Deck construction relied on digital construction planning and off-site manufacturing techniques to improve installation efficiency.
A total of 1,024 precast concrete segments were manufactured at a dedicated facility in Kingsbury before transportation to site. Each segment was then lifted into position to form spans supported by 54 reinforced concrete piers reaching heights of up to 12 metres.
The central deck, measuring 22 metres wide, consists of twin rows of 11-metre segments weighing around 60 tonnes each. Adjacent single-track viaducts were assembled from smaller 44-tonne segments.
BBV deployed a cantilever construction method, temporarily supporting segments using steel cables until each span was completed. Permanent post-tensioned cables were then threaded through the structure to deliver long-term strength and stability. This sequence was repeated across all piers to complete deck assembly.
Supporting HS2 infrastructure delivery
Segmental viaduct construction across HS2 relies heavily on digital construction management, Building Information Modelling coordination and precision engineering controls to align structures across multiple spans.
Simon Albarel, Section Manager at Balfour Beatty VINCI, said: “We’re continuing to make great progress on the construction of HS2’s Delta Junction, one of the most complex sections of the entire route. Our latest milestone is the successful installation of 1,024 pre-cast segments along all the Coleshill Viaducts.
“Completing the deck assembly is another great achievement for the team, demonstrating their precision engineering and hard work over the last two and a half years.”
With deck installation complete, teams are progressing kerbs, parapets and finishing works required before track systems are installed.
Next steps for HS2
Construction continues across the 140-mile HS2 route linking London and Birmingham, where multiple structures, stations and earthworks remain underway. HS2 Ltd Chief Executive Mark Wild is overseeing a programme reset intended to improve efficiency and manage delivery costs across remaining works.
Completion of the Coleshill viaduct decks represents a significant achievement in applying digital construction, off-site manufacturing and large-scale infrastructure coordination within the UK rail sector.
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