HS2’s Greatworth Tunnel Hits Key Milestone with Road Realignment

Construction of the longest “green” tunnel on the HS2 line, the 1.7-mile (2.7km) Greatworth Tunnel in south Northamptonshire, has taken a major step forward with the temporary realignment of the B4525 road, HS2 Ltd has confirmed.

The tunnel, built using a cut-and-cover method, is designed to minimise disruption to the surrounding rural landscape. Engineers have already completed around 0.6 miles (1km) of the structure, which will eventually be covered with soil, trees, shrubs, and hedgerows to blend into the environment.

Sam Arrowsmith from HS2 Ltd said: “The tunnel will protect the rural landscape and reduce disruption for people living nearby.”

The tunnel is assembled from precast concrete segments in an “M” shape, with separate halves for northbound and southbound trains. Chris Barrett, a senior engineer at contractor EKFB, said that lessons learned from the nearby Chipping Warden Tunnel have helped accelerate construction, allowing roads to reopen and communities to remain connected.

HS2 trains will travel underground for 32 miles in total, with major tunnels under the Chilterns and approaches to London and Birmingham built using tunnel boring machines. The Greatworth Tunnel is one of five cut-and-cover tunnels on the route.

HS2 Ltd said the new line will improve journeys between London and Birmingham and free up capacity on the West Coast Main Line for more freight and local services. The service had originally been expected to open by 2033, but this target is no longer expected to be met, and no updated timetable has been announced.