Road realignment is major step for HS2, says firm

The construction of the longest "green" tunnel on the HS2 line has taken a "major step forward" with the realignment of a local road, its developer said.

The 1.7-mile (2.7km) Greatworth Tunnel in south Northamptonshire uses a cut-and-cover process, where land is excavated, the tunnel put in place and then the area is covered with greenery.

Engineers working on the high-speed rail project have already assembled 0.6 mile (1km) of the structure, and the temporary realignment of the B4525 will free up space for the next phase of excavations for the tunnel.

Sam Arrowsmith, from HS2 Ltd, said the tunnel would "protect the rural landscape and reduce disruption for people living nearby".

He said that "lessons" learned from the nearby Chipping Warden Tunnel, which uses a similar design, had "helped us significantly increase productivity" on the project.

Assembled from precast concrete segments, the tunnel is designed in an "M" shape, with separate halves for northbound and southbound trains.

Chris Barrett, a senior engineer at contractor EKFB, said: "Implementing the construction improvements and learnings from the Chipping Warden tunnel has allowed us to accelerate the unit installation of the Greatworth Tunnel.

"This means that we can reopen roads and further connect our communities.

"Opening these roads unlocks the next phase of excavation work on the tunnel, which will allow us to progress with construction through the winter months."

HS2 trains will travel underground for 32 miles, with major tunnels under the Chilterns and the approach to London and Birmingham dug using tunnel boring machines, as well as five cut-and-cover tunnels similar to the one at Greatworth.

HS2 Ltd said it aimed to improve journeys between London and Birmingham while freeing up space on the existing West Coast Main Line for more freight and local services.

The service was expected to be open by 2033, but in June the government announced this target would not be met and no updated timescale has yet been provided.

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