HS2 main works contractor EKFB has completed the central section of a green tunnel at Wendover in Buckinghamshire.
The 1.4km cut-and-cover tunnel is being built inside a cutting alongside the A413 to the west of the town. Once each section is complete, earth is being put back on top to blend the railway into the surrounding landscape.
There are five green tunnels on the HS2 project between London and Birmingham. The Copthall tunnel, on the outskirts of the capital, was completed in the summer.
Assembled from 2,740 precast concrete segments, the Wendover green tunnel is an ‘M’ shape, with separate halves for northbound and southbound trains.
To speed up construction, the tunnel was built in two sections to allow excavation, preparatory work, construction and backfilling to occur at different points simultaneously. The two halves met this week, with the last segment slotted into place on Monday.
EKFB, comprising Eiffage, Kier, Ferrovial Construction and Bam Nuttall, will now focus on the portals, internal works and backfilling. Also, a road that has been carried over the construction site on a temporary bridge will be realigned over the top of the tunnel.
More than 1.2 million m3 of material – mainly chalk – was excavated to form the level base for the tunnel. This was stored on site and is now being backfilled and compressed to ensure the weight is spread equally across the structure.
Wendover is one of three green tunnels being built by EKFB – the main works contractor for HS2’s central section through Buckinghamshire and into South Warwickshire – with lessons learnt shared between the teams to help improve productivity and construction speeds.
This includes prefabricating, reinforcement cages for the base slab, improving the delivery of concrete through the tunnels and testing to safely increase the size of machinery backfilling the tunnel.
While most of the segments were lifted with a crane, those under the Ellesborough Road temporary bridge were lifted into position using a self-propelled modular transporter.
Supported by 16 sets of wheels, the machine allowed engineers to lift the beams from underneath and place them precisely into position beneath the bridge.
EKFB project manager Elton Qafaliaj said EKFB installed the first concrete segment in spring 2025 and lifted more than 2,000 segments in less than 18 months to complete the central structure.
“This was a huge undertaking and has required the expertise of a skilled workforce. The team has worked together to safely overcome challenges, keeping productivity high and pushing the construction programme forward,” he said.
“Seeing the two halves of tunnel finally come together was a proud moment for everyone involved.”
