The proposed Trans-Pennine Tunnel, linking Sheffield with Manchester, would be “the most ambitious road scheme since the construction of the first motorway fifty years ago”. That’s according to an interim report published by Highways England.
Highways England goes on to call for a national debate, claiming the “engineering and delivery of such a tunnel would be a national first”.
In its preliminary findings, Highways England has concluded there is a “clear strategic case for the scheme”, with motorists benefitting from reduced journey times and the improved resilience of a subterranean route. But extensive tunnelling through a National Park and the associated connections to the existing road network present significant technical challenges.
One of the longest tunnels ever built
The proposed strategic road link between Sheffield and Manchester ranges from 25 to 31 miles long and includes a tunnelled section, which could be between 12.4 and 18.6 miles, making it one of the longest tunnels ever built.
The longest road tunnel in the world is the Laerdal tunnel in Norway, which took around five years and more than a billion kroner (£76 million) to construct. For years, the St. Gotthard tunnel, linking the Swiss cantons of Uri and Ticino, was the longest in the world, but that has since been eclipsed by the Laerdal tunnel, along with one in Japan and two in China.
In the UK, the Hindhead Tunnel is the longest under-land road tunnel in the UK, with 1.14 miles stretching below the Devil’s Punch Bowl in Surrey.
Highways England claims a strategic link would provide productivity benefits of between £171 million and £421 million per annum, but isn’t clear on how the new route will be funded. A road-user toll hasn’t been ruled out, but a decision on whether or not to toll the road is outside the scope of the current study.
The journey between Manchester and Sheffield via the Pennines is approximately 45 miles and takes an average of 85 minutes. The same journey via the M62 is around 75 miles in length and takes 95 minutes, which is why only 10% of trips between the two cities are via the motorway.
Should the tunnel get the go ahead, Highways England expects journey times to reduce by up to 30 minutes, with traffic congestion on other parts of the network reduced as the capacity increases. There’s also the benefit of a tunnel not being affected by adverse weather conditions.
The Trans-Pennine route is likely to comprise a dual carriageway built to motorway standards, but Highways England is considering “less conventional solutions” for the tunnel sections. As the tunnel will be designed to have an operational life of 120 years, a high degree of future proofing is required.
Tunnel the only credible solution?
In its Road Investment Strategy (RIS) report of 2014, the Department for Transport (DfT) concluded that “the invaluable landscapes and ecological significance of the Peak District National Park rule out a surface link. The only credible solution may be to construct a tunnel under the central part of the Pennines”.
In the executive summary, Highways England said: “Such a connection could have a dramatic impact on the economy of the north, particularly in combination with plans for high-speed rail links. It would be capable of fundamentally changing the nature of the journey between two of the most important cities of the north.
“But the invaluable landscapes and ecological significance of the Peak District National Park rule out a surface link. The only credible solution may be to construct a tunnel under the central part of the Pennines. This carries with it the potential to bring important environmental improvements to the Peak District National Park.”
The results of the strategic study will be published in the autumn of 2016.
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