The West Highland Railway opened in 1901 between Fort William and Mallaig. The contractor was Robert McAlpine & Sons. McAlpine was enthusiastic about the use of concrete and the Mallaig line was accordingly a proving ground for the use of the new material, mass concrete (not containing steel reinforcement).

Glenfinnan is the most famous of the viaducts on the line, notable for its 21 arches and for being built on a 12 chain radius curve. Another bridge on the line, Borrodale, was for a time the longest single concrete span in the world. Both continue in use.

Located at the top of Loch Shiel in the West Highlands of Scotland, the viaduct overlooks the Glenfinnan Monument and the waters of Loch Shiel.

The viaduct was constructed by Robert McAlpine & Sons which was headed by Robert McAlpine, nicknamed "Concrete Bob" for his innovative use of mass concrete. Concrete was used due to the difficulty of working the hard schist in the area. McAlpine's son Robert, then aged 28, took charge of construction, with his younger son Malcolm appointed as assistant.

Construction of the extension from Fort William to Mallaig began in January 1897, and the line opened on 1 April 1901. The Glenfinnan Viaduct, however, was complete enough by October 1898 to be used to transport materials across the valley. It was built at a cost of GB£18,904.

The viaduct's spectacular location and visual appeal gave it a role in four Harry Potter films. It is now popularly known as the "Harry Potter Bridge" over which Hogwarts Express (The Jacobite Steam Train) passes. In the flying car scene in Harry Potter and the Chamber of Secrets, Ron and Harry in the flying Ford Anglia find themselves being chased across the bridge by the train.

Account of the unveiling event:

Heavy rail rain at Glenfinnan Station failed to dampen spirits on Sunday 18th August 2019 when our president, Lady Judy McAlpine, unveiled our second Scottish Red Wheel at Glenfinnan Station.

Judy was joined on the afternoon Jacobite service from Fort William, by John Barnes of the Glenfinnan Railway Museum, Andy Savage of the Railway Heritage Trust, Jerry Swift of the Transport Trust, Hege Hernes who is the museum’s curator and Doug Carmichael of the Friends of the West Highland Lines.  Our thanks to West Coast Railways for making the trip possible – it was good to see West Coast’s James Shuttleworth at the unveiling as the Jacobite paused to let the returning morning Jacobite pass, giving a great opportunity for many more people to see the unveiling.

Jerry introduced the Trust and the Red Wheel scheme, saying how keen the Trust have been for several years to mark the significance of what is now such an iconic structure, the mass concrete Glenfinnan Viaduct.  Thanks to Harry Potter films, this structure can genuinely be called iconic – ask anyone who knows anything about the films!  But more importantly for the Trust, it was built by our late President’s family as part of the West Highland Extension, a truly remarkable engineering feat through some really tough country where using the local hard rock for masonry was not an option – hence the extensive use of mass concrete.

Our new President, Judy was delighted to unveil the Red Wheel by removing a McAlpine tartan kilt!  And a young piper played a number of well-known Scottish pipe pieces. All this as the heavens opened.

Hege Hernes then went on to describe the history of the extension, the viaduct, and the part of the McAlpine family in its construction.

To round of off the day, a number of us were privileged to see a selection of photographs recently discovered of the construction of the Extension.  Unlike the other photographs which were known to exist (held by the National Railway Museum), these negatives by an unknown photographer showed much more mundane scenes of the people and the construction rather than formal pictures of the engineering structures.

The photographs were found by a photographer who collects heritage photographs at an auction in the South West.  There are around 200 of them and they included local roads, buildings, the railway, people and the railway’s hospital.  They also include some photos taken in Ireland and in North America.  Given the access they clearly show the photographer had, Hege has proposed the really exciting proposition that they may have been taken by Malcolm McAlpine, Bill’s great uncle, who was seriously injured in an accident on the railway and whose story almost defies belief:  Hege is proposing a book which if published will be well worth reading.

Our thanks to everyone involved in this splendid unveiling and to the Glenfinnan Museum in particular for hosting our second Scottish Red Wheel.

Jerry Swift