The last of more than 2,700 enormous deck segments for HS2’s Delta junction, a complex triangular network of viaducts outside Birmingham, has been manufactured at a purpose-built factory.
The deck segments, which each weigh up to 85 tonnes, were made at a temporary outdoor facility alongside the M42 near Kingsbury in Warwickshire. They are then moved to the nearby construction sites by road before being lifted and secured into position to form the spans of the viaducts.
The Delta Junction is one of the most complicated parts of the HS2 project, carrying the high-speed line across a dense web of motorways, local roads, railways, rivers and floodplains. Two major groups of viaducts (at Coleshill and Water Orton/River Thame) are being built using pre-cast segments from Kingsbury.
So far, the team has installed around three quarters of the 2,742 segments produced at Kingsbury, recently completing the deck assembly for the Coleshill viaducts and successfully completing the key spans for the Water Orton 1 and 2 viaducts which cross the busy A446.
With the deck segments complete, the facility will now focus on other pre-cast components needed for the project, including deck slabs for Birmingham’s Curzon Approach viaducts.
HS2 Ltd’s head of delivery, Caroline Warrington, said: “Casting these enormous segments on site, close to the viaducts, helps us deliver a quality product and reduce disruption for road users. It’s great to see the final segments complete and I’d like to thank everyone involved in the manufacturing process.
“With this part of the work finished, the team can begin to focus on the deck slabs for the approach viaducts which will carry the railway into central Birmingham.”
Over the last three-and-a-half years, the precast yard turned out up to eight segments per day, weighing between 50 and 85 tonnes. The segments are 3.5 metres high and come in widths of 7 metres or 11 metres, to support single track and double track sections of the railway. Together they will form more than four miles (6.5km) of viaduct decks.
The viaducts are assembled using a cantilever process with temporary steel cables supporting the segments until the span is complete. Permanent post-tensioned cables are then installed in the hollow centre of the viaduct to strengthen the structure. The same process is repeated between each pier until all the spans are complete.
However, 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.
Image credit: HS2