Wendover green tunnel joins up as HS2 completes central section of 1.4km structure

HS2 Ltd said on 6 October that contractor EKFB had placed the last precast segment on the central part of the Wendover green tunnel in Buckinghamshire, linking the two halves of the 1.4km cut-and-cover structure for the first time.

The tunnel is being built in a cutting alongside the A413 to the west of the town, with earth placed back over each finished section, according to HS2. The structure was built as two sections working at the same time so that excavation, preparation, assembly and backfilling could run in parallel, and the halves met this week when the final segment went in on Monday.

The team signed the segment before it was lifted into place, HS2 said.

Umesh Gorasia, HS2 Ltd's Project Manager, 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."

The structure

HS2 said the Wendover tunnel is assembled from 2,740 precast concrete segments in an M shape, with separate halves for northbound and southbound trains. HS2 said in 2022 that the double arch is formed from five segment types: a central pier, two side walls and two roof slabs.

All 13,290 segments for the Wendover, Chipping Warden and Greatworth tunnels are being made by Stanton Precast Ltd at its factory in Ilkeston, Derbyshire, in a deal HS2 said at the time was expected to create up to 100 jobs there. HS2 said the lighter modular approach, developed by EKFB using lessons from the latest French high-speed lines, was expected to more than halve the carbon embedded in the tunnel structures.

Most segments at Wendover were placed by crane, HS2 said. Those under the temporary bridge that carries Ellesborough Road over the site were moved in with a self-propelled modular transporter on 16 sets of wheels, which lifted the beams from underneath and set them beneath the bridge.

Elton Qafaliaj, EKFB's Project Manager, said: "EKFB installed the first concrete segment in spring 2025, and in less than 18 months, we have lifted more than 2,000 segments to complete the central structure of the Wendover green tunnel."

Wendover Parish Council's HS2 monthly report for April 2025 recorded that work had started on a 230m section of the tunnel just north of Ellesborough Road using precast arch segments.

EKFB is HS2's main works contractor for the central section of the route through Buckinghamshire into South Warwickshire. It is a joint venture of Eiffage, Kier, Ferrovial Construction and Bam Nuttall.

Earthworks and lessons shared

More than 1.2 million cubic metres of material, mainly chalk, was excavated to form the level base for the tunnel, HS2 said. It was stored on site and is now being backfilled and compressed so that the weight is spread evenly across the structure.

Wendover is one of three green tunnels EKFB is building, and HS2 said lessons are shared between the teams, including prefabricating reinforcement cages for the base slab, improving concrete delivery through the tunnels and testing to safely increase the size of backfilling machinery.

When HS2 announced on 3 July that the last of 5,020 segments had been placed at Chipping Warden in Northamptonshire, it said the installation rate there had doubled from an average of two segments a day in 2022/23 to five and a half a day, and that lessons from that site were being applied at Wendover and Greatworth, which use a similar precast method.

The green tunnel programme

HS2 said about 65 miles (105km) of tunnels will be built between London and the West Midlands, most of them bored. Five are cut-and-cover tunnels: Wendover, Chipping Warden, Greatworth, Burton Green and Copthall in Hillingdon. HS2 calls them green tunnels because the surface is planted with local trees, shrubs and vegetation once the structure is finished.

Copthall, near West Ruislip, was the first to be completed, HS2 announced on 7 July. Greatworth in West Northamptonshire is the longest on the route, according to HS2's project page.

Green tunnel	Length (metres)
Greatworth	2,700
Chipping Warden	2,500
Wendover	1,400
Copthall	880
Burton Green	700

Source: HS2 Ltd green tunnels project page.

What happens next

With the central section done, HS2 said attention at Wendover turns to the portals at each end, completing the floor slab and the internal fit-out, while backfilling continues.

The final stage will be to realign Ellesborough Road, which runs from Wendover towards Princes Risborough, over the top of the tunnel and complete the landscaping.

HS2 said significant work remains across the 140 miles between London and Birmingham, with chief executive Mark Wild leading a reset of the project to deliver the rest of the route as efficiently as possible and at the lowest reasonable cost.