Time for a tunnel at the Rest?

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Transport Scotland is failing to understand the Rest and be Thankful, according to one of Scotland’s leading industrialists, an experienced civil engineer.

As the government agency searches for a permanent solution to an increasing landslide threat to the lifeline A83 trunk road, Sir William Lithgow of Ormsary claims the answer is staring them in the face.

Sir William is a keen proponent of a tunnel, viaduct and raised carriageway through Glen Croe.

According to Sir William, the cost estimates used by Transport Scotland are based on boring through soft rock, where reinforcement is needed. At the Rest, the underlying rock is believed to be hard enough to be self-supporting, significantly reducing the cost and complexity of tunnels.

He has invited a high level delegation from the Scottish Government and Transport Scotland to inspect tunnel projects among similar terrain in Norway.

After Sir William contacted Transport Scotland chief executive Roy Brannen to set out his proposals, he received a reply in late May from Transport Scotland project administrator Cara Reid on Mr Brannen’s behalf.

Ms Reid states in the letter: ‘Looking at the tunnels costs specifically, these have been developed from a database of past projects across the UK and wider Europe, which is British Tunnelling Society/Infrastructure UK treasury accepted.

‘As an example of a recently completed tunnel project in the UK, Hindhead Tunnel in Surrey, a 1.8km twin-bore tunnel, reported a cost of £371m at 2006 prices. The tunnel costed for the [Rest and be Thankful option involving a tunnel] pink option is approximately 3km long.

‘To compare the Hindhead tunnel in soft terrain with Glen Croe with hard rock tunnelling country, is a threefold increase in cost ascertained from finished Norwegian projects.’ responded Sir William.

‘Given the will, a secure route could be completed by Autumn 2023.’

He continud: ‘Hard rock tunnels, being supported by the rock through which they are cut, cost a fraction of lowland tunnels which have to derive their strength from thick lining rings.’

Sir William also claims that Transport Scotland has misunderstood the fractured nature of the hilltops in the area, where artesian aquifers are a common phenomenon.

‘Artesian aquifers from the fractured high tops liquidise under pressure,’ he explained, ‘covering soil and boulders on the lower slopes. This can only be exacerbated by climate change.’

Advising against constructing even mitigation measures in this type of landscape, he added that ‘one must work with terrain’s grain, as did the giants on whose shoulders we stand, who gave Scotland her outstanding ability to solve problems.’

Ms Reid continued in her letter: ‘We recognise that the timescales for developing an alternative to the current route and finding a long-term solution to the challenges created by the Rest and be Thankful are frustrating for the local community.

‘…it is important that the correct statutory process is followed to ensure a fair and transparent assessment of options and impacts on local communities and road users.’