Engineers working on HS2’s complex triangular intersection outside Birmingham have successfully completed the construction of four parallel viaduct decks – an essential part of the huge project.
The viaducts being built near Coleshill in Warwickshire stretch for more than 600m and form a small part of the Delta junction – a huge intersection being built to the east of Birmingham for the new high-speed railway.
Like the nearby Spaghetti Junction, the Delta is formed of a series of interconnected viaducts, flyovers and underpasses, taking the high-speed line over motorways, local roads, railways, rivers and floodplains.
The Coleshill East and West viaducts form the southern part of the junction, where the railway split apart as it crosses a local road and the floodplain of the river Cole, between the M6 and M42.
Two parallel viaduct spans will carry the four-track mainline running north and south, while two narrower viaducts on either side will carry services to and from the new Birmingham Curzon Street station in the city centre.
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.”
The construction of the Coleshill viaducts – which stretch for a combined total of 2.4km – is being delivered by HS2’s main works contractor in the Midlands, Balfour Beatty VINCI.
The decks are made of 1,024 individual concrete segments which were manufactured off-site at a purpose-built facility a few miles away at Kingsbury. These were then moved to site before being lifted and secured into position to form the spans of the viaducts.
The central 22m wide deck consists of two rows of 11m wide segments, each weighing 60 tonnes, while the two single track viaducts are made of single rows of smaller, 44 tonne segments. They are supported by 54 reinforced concrete piers, each up to 12m high.
BBV used a cantilever process to install the segments with temporary steel cables supporting each one until the spans were complete. Permanent post-tensioned cables were then installed in the hollow centre of the viaduct to strengthen the structure.
The same process was repeated between each of the piers until all the spans were complete.
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 the deck segments now installed, the focus is turning to the finishing works, with the robust kerbs and parapets still to be completed.
Elsewhere, there is still significant work to do across the whole 140 miles between London and Birmingham. Mark Wild, HS2 Ltd Chief Executive, is now leading a comprehensive reset of the project to ensure the remainder of the route is delivered as efficiently as possible and for the lowest reasonable cost.
