HS2 completes construction in Buckinghamshire on its longest tunnel
HS2 Ltd has announced the completion of work on its longest tunnel, which is located within Buckinghamshire.
This week, the longstanding project announced it had completed its Chiltern tunnel which starts in South Heath near Great Missenden and passes through to the Hertfordshire-Buckinghamshire border in West Hyde.
HS2 revealed that work on the tunnel, which is 10 miles long, began almost five years ago. While construction work has finished the tunnel still needs to be fitted with tracks and overhead electrical equipment as part of later phases of the project.
Data released by the project shows that trains will travel through the tunnels at 200mph and will complete that section of the journeys between London and Birmingham in just three seconds.
Work on the site began in 2021 and two 2,000-tonne tunnel boring machines (TBMs) were used to create the tunnel.
“Five deep ventilation and access shafts were sunk to depths of as much as 78 metres along its route and completed before the TBMs’ arrival,” a project spokesperson revealed. “The understated design of each shaft’s headhouse, by Grimshaw architects, is intended to blend unobtrusively with the surrounding landscape of the Chiltern hills.”
It is the second of HS2’s five twin-bore tunnels to be structurally complete after the one-mile Long Itchington Wood tunnel was completed in Warwickshire.
HS2 Ltd head of civil engineering for Chiltern tunnel, Mark Clapp said: “Multi-facetted projects of the Chiltern tunnel’s scale and complexity don’t often come along; as a civil engineer, you’re lucky to be involved in anything like it. The team we assembled at HS2 Ltd, and with Align JV – our main civil works contractor - and all its subcontractors, to deliver this part of the new high-speed railway was exemplary.
“I pay tribute to everyone involved. They can all feel certain that their hard work will stand the test of time.”
A purpose-built factory was opened near to the tunnel’s southern portal for the project. The TBMs excavated three million tonnes of chalk during the project.
The excavated material has been used on site to create more than 120 hectares chalk grasslands around the tunnel’s southern portal on the Herts/Bucks border. Completion of civil engineering works will be followed by the installation of mechanical, electrical and plumbing equipment, with the design-phase already underway.