Construction of a 700-metre-long ‘green tunnel’ for HS2 in Warwickshire has now reached halfway.

The tunnel is at Burton Green near Kenilworth, and 150 people working on its construction have sunk over 1,300 piles using 33,000 cubic metres of concrete.

The entrance to the tunnel’s southern portal has been completed, as well as complex underground structural elements including retaining walls.

Burton Green is one of five ‘green tunnels’ being built for HS2 that are less deep than normal tunnels.

Once complete, trees, plants and shrubs will be planted on top to help them blend into the natural landscape and will feature a green space above for use by the local community.

HS2’s main works civils contractor for the West Midlands, Balfour Beatty VINCI (BBV) is constructing Burton Green Tunnel.

It was designed by Mott MacDonald engineers from the Mott MacDonald SYSTRA Design Joint Venture (DJV).

A ‘top-down’ construction method is being used which includes initially building the side walls and roof of the tunnel, with large openings to ease excavation, and then excavating the tunnel before constructing the tunnel base.

Completion of the tunnel is planned for autumn 2026 but, before then, further tunnel excavation work is required, with the excavated soil being reused as part of wider landscaping plans.

Roof slabs, base slabs, and internal structures also need to be installed.

Construction of the Burton Green tunnel has necessitated the realignment of Kenilworth Greenway.

That is an important link from Balsall Common to Kenilworth via Burton Green for walkers, cyclists and horse-riders.

While the railway is being built, HS2 has created a temporary route from Burton Green Village Hall via the existing field boundaries linking with Berkswell Station in the northwest.

After all construction and landscape work is complete, Kenilworth Greenway will be reinstated to near its original alignment and pass over the top of the new tunnel.

The longest green tunnel on HS2 is near Greatworth in West Northamptonshire.

“We’re incredibly proud to have achieved the 50% completion mark here at Burton Green Tunnel and to be celebrating this milestone moment. Delivering a complex structure of this scale requires a huge amount of expertise and energy, which is thanks to everyone involved – from onsite engineers and machine operators, to design and support colleagues working behind the scenes.”

Doug Barnett, Senior Project Manager for HS2 Ltd