The central structure of HS2’s green tunnel at Wendover, Buckinghamshire, has been completed after the final precast concrete segment was installed on Monday.
The 1.4km cut-and-cover tunnel is being built in a cutting alongside the A413, west of the town. Once construction is complete, earth will be placed over the structure and the railway landscaped to reduce visual and noise impacts.
Construction moves to final stages
The tunnel is formed from 2,740 precast concrete segments in an ‘M’ shape, with separate structures for northbound and southbound trains. Construction was split into two sections so excavation, preparation, assembly and backfilling could take place concurrently.
Work will now focus on the portals at either end, completion of the floor slab and internal fitout. Ellesborough Road, which is currently carried over the site on a temporary bridge, will eventually be realigned over the top of the tunnel before landscaping is completed.
More than 1.2 million cubic metres of material, mainly chalk, was excavated to create the tunnel’s level base. The material has been stored on site and is being returned in layers and compacted to distribute the load evenly across the structure.
HS2 Ltd project manager Umesh Gorasia said: “It’s great to see the two halves of the tunnel linked up for the first time. Once complete, the green tunnel will dramatically reduce disruption from passing trains and blend the railway into the countryside.
“There’s still some way to go, but we’re making good progress and I’d like to thank the team for all their hard work.”
EKFB-led works
The work is being delivered by EKFB, the joint venture of Eiffage, Kier, Ferrovial Construction and Bam Nuttall responsible for HS2’s main works through central Buckinghamshire and into South Warwickshire.
EKFB project manager Elton Qafaliaj said the first concrete segment was installed in spring 2025 and that more than 2,000 segments had been lifted in less than 18 months to complete the central structure.
Most of the segments were installed by crane. Those beneath the temporary Ellesborough Road bridge were positioned using a self-propelled modular transporter, which enabled engineers to lift and place them from below the bridge.
Wendover is one of three green tunnels being delivered by EKFB. The project team is applying lessons from the sites to improve productivity, including prefabricating reinforcement cages, refining concrete deliveries through the tunnels and trialling larger backfilling machinery.
HS2 is due to build five shallow cut-and-cover green tunnels between London and the West Midlands: at Wendover, Chipping Warden, Greatworth, Burton Green and Copthall in Hillingdon. The wider programme includes about 105km of tunnels and the excavation of around 130 million tonnes of earth.