A stalled plan for a road tunnel between Manchester and Sheffield could be revived under proposals that could dramatically slash construction costs. However, a reinforced concrete framework will still likely be part of the final structure.
The original plan was mothballed amid projections that it would cost £10.6 billion to use boring machines to excavate the tunnel under the Peak District hills.
However, infrastructure group Future Works recently proposed to revive the scheme using the ‘drill and blast’ method used to construct tunnels under mountains in Norway, with a projected cost of around £2 billion.
Why Is A Tunnel Under The Pennines Being Proposed?
The plan has been supported by the East Midlands County Combined Authority, amid concerns that the connections between the two cities are currently inadequate:
- At present, road traffic has to take either the Woodhead or Snake Passes, both of which are slow routes and prone to closures due to landslips and winter weather.
- Traffic on these roads impacts the environment as thousands of cars meander across the Peak District National Park landscape.
- However, the government has cited “significant financial and environmental costs” as a barrier to the idea of a road tunnel.
If the proposals gain a more favourable response from a government now led with a northern-centric aim by Andy Burnham, this could prove transformational.
Although the tunnel would be carved out of the rock in a different way, it would still be likely to have a reinforced concrete lining. This is because reinforced concrete is a feature of the ‘Norwegian method’ of excavation.
Often this is sprayed on, with research indicating up to 60,000 cubic metres of fibre-reinforced shotcrete has been applied in tunnels per year in a mass tunnelling programme spread over decades.
What this highlights is the fact that, irrespective of the excavation method, tunnels need protecting against a range of potential threats from loose rock to water ingress.
Reinforced concrete is an effective means of ensuring the tunnel remains safe and usable, which is why, if the Manchester to Sheffield tunnel is ever built, this will almost certainly be the lining method of choice.
