Christmas Engineering Push Advances HS2 Delta Junction at Water Orton
Work on one of the most technically demanding elements of the HS2 project has reached a new milestone, with engineers completing two major viaduct spans over an existing railway near Water Orton during the Christmas period.
The newly installed spans form part of the Delta junction, a vast triangular rail interchange under construction to the east of Birmingham. The junction will allow high-speed trains to travel between Birmingham, the main HS2 route heading north and south, and associated infrastructure including depots and connecting lines.
Designed on a scale more commonly associated with major motorway interchanges, the Delta junction consists of a network of viaducts carrying HS2 over roads, railways, rivers and floodplains. To allow trains to maintain speeds of up to 360km/h on the main line, and around 200km/h on the Birmingham approaches, the junction extends across a wide area, incorporating 2.6 miles of track, flyovers, underpasses and five substantial viaduct structures.
The Water Orton viaducts sit at the northern edge of the junction and will enable southbound services to diverge onto the spur leading into Birmingham Curzon Street and the Washwood Heath rolling stock depot. Their construction advanced significantly after engineers used a five-day closure of the Birmingham to Peterborough railway line over Christmas to safely install two parallel spans. During the closure, rail replacement buses operated between Birmingham New Street and Coleshill.
With the railway crossing now complete, construction teams will turn their attention next year to extending the viaducts over the nearby A446 and the M42 motorway. When finished, the two single-track structures will stretch for approximately 1.4 kilometres, spanning two railways, a river, local roads and the motorway network.
The viaducts are being built using pre-cast concrete segments assembled with a cantilever construction method. Each section is supported by temporary cables while permanent post-tensioned cables are threaded through the hollow core of the structure, allowing the process to move forward span by span. A total of 32 concrete piers, some standing up to 20 metres high, support the viaducts and have been cast on site using bespoke formwork, with reinforcement manufactured locally at Coleshill.
Across the wider Delta junction, around 3.7 miles of viaduct are being built using the same approach. In total, 2,742 concrete segments are being produced at a temporary factory established at nearby Lea Marston.
Sam Hinkley, HS2 Ltd’s Senior Project Manager said:
“It’s great to see the Water Orton viaducts in place across the railway and I’d like to thank everyone who gave up their Christmas to help us reach this important milestone and I’d like to thank passengers for their patience. These precast segmental viaducts form a key part of the Delta junction – one of the most complex parts of the HS2 project and I look forward to seeing more progress in the year ahead.”
Stephane Ciccolini, Senior Works Manager at Balfour Beatty VINCI, said:
“This complex section of the HS2 route has taken a major step forward, after BBV teams successfully erected two viaducts spans over an existing railway near Water Orton. We’ve worked around the clock during the Christmas period to deliver this incredible feat of engineering, using a specialist cantilever technique not seen in the UK before this project. This approach involves using a 22-metre-high mast and a 14-metre-high swivel crane to move each individual segment into place until the span is complete.”
Image: HS2