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Loch Awe Viaduct

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Loch Awe Viaduct
Location Map ( geo)
A85-loch-awe1.jpg
Cameraicon.png View gallery (2)
From:  Falls of Cruachan
To:  Pass of Brander
Location
Loch Awe
County
Argyll
Highway Authority
Transport Scotland
Additional Information
Bridge Type:  Concrete Bridge
On road(s)
A85
Crossings related to the A85

The Pass of Brander is a narrow defile carved out by Loch Awe many millenia ago as a short cut to the sea - previously the loch had flowed south, reaching the coast near Loch Crinan. For centuries the Pass of Brander has been a major east-west route connecting Oban and north Argyll with Tyndrum and routes south. The first formal road, as opposed to drovers routes, was the old Military road built by Major Caulfeild in the mid 18th century. At the beginning of the 19th century, Thomas Telford rebuilt much of the road, although the evidence all suggests that he maintained the same alignment through the pass.

Roll on to the end of the 19th century, and the Caeldonian Railway's Callendar and Oban branch was also taken through the pass, often just a few feet higher up the hillside than the road. This, naturally, led to problems more recently!

The old road

Old maps and evidence on the ground all suggest that the road built by Caulfeild and subsequently rebuilt by Telford ran along the loch's shore for most of the route, and never closer than just northwest of the Falls of Cruachan. This also seems to be the point where the hill is at its steepest, and so the railway line appears to be closest.

When the road was rebuilt in the 1960/70s (?), it would appear that blasting and preparation works have destroyed much of the old road, but from what remains this particular stretch must have been extremely narrow and trapped between the waters edge and cliffs. Whilst there is a Hydro station with dam further west in the pass, it is not believed that this has adjusted the level of the loch by any significant amount.

A Viaduct

The old single-track road was obviously unfit for purpose as traffic levels increased after the war, and as with so many other roads in the Highlands, a major scheme of improvements was planned. The Pass of Brander would have been a particularly difficult section to work on, with the section to the north west of the Falls of Cruachan the largest engineering challenge. Further west, the old road has been retained as laybys to give a feeling for what improvements were made.

The Loch Awe Viaduct

The solution to the worst part of the pass was to build a viaduct into the loch to carry the new S2 roadway. Unless you put a boat on the loch, the only way of seeing the underside of the road is from the Cruachan Visitor Centre car park, and from here it is clear that the road is supported by a series of concrete piers set into the loch bed. The concrete deck is then cantilevered either side of the pier, and does not appear to have any connection with the cliff behind, at the eastern end at least. The viaduct extends along the loch, curving round the cliff, for approximately 400m.

A Train and a 1000 Tonne Crane!

In the early summer of 2010, a freak accident saw a train become derailed in the pass after hitting a boulder that had fallen onto the tracks. Fortunately, no one was killed, and injuries were generally slight. However, it did leave the train hanging precariously off the line, with just a few trees and its second carriage stopping it dropping onto the road below.

Unsurprisingly, the road was closed while the authorities tried to work out what to do. The only real answer was to bring in a crane, park it on the viaduct below the train and lift the train onto a waiting lorry. While this may not sound that tricky, the crane needed had a 1000 Tonne payload, and weighed so much that the structural integrity of the viaduct could be put at risk. The solution was to reinforce the road deck before moving the crane into place and assembling it. The train was then successfully lifted clear and removed from the site.

Before the road was reopened, the structure of the viaduct was inspected, and found to be none the worse for its ordeal. It did, however, mean that the A85 was closed for nearly a fortnight, and the railway line slightly longer, so severing Oban's main contact with the outside world.




Loch Awe Viaduct
Related Pictures
View gallery (2)
A85-loch-awe1.jpgA85-loch-awe2.jpg

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