Loch Treig Tunnel

Location type


Name and dates

Loch Treig Tunnel (1929-)

Opened on the West Highland Railway.


This is a single track and single bore tunnel of 450 ft on the east side of Loch Treig close to, and to the south of, the closed Fersit halt. It is built on a deviation from the original route, which was just to the west and at a lower level.

The tunnel was created in 1929 when Loch Treig became a reservoir for the Lochaber Smelter and its level was raised. The Loch Treig Dam is 2/3 of a mile to the north. A portion of the trackbed had to be raised above the new high water level of the loch. The disused section of the line is usually covered by water. At low water the portion alongside the tunnel is well preserved: a stone shelf cut out of a hillside. The original route did not require a tunnel.

Also known as Fersit Tunnel.


Tunnel diversion deviation Loch Treig


Fersit Tunnel

Nearby stations
Fersit Halt
Roy Bridge
Spean Bridge
Invergloy Platform
Banavie Pier
Fort William
Fort William [1st]
Loch Treig Dam
Tulloch Viaduct
Allt Coire Mheadhoin Viaduct
Loch Treig
Stob Coire Sgriodain
Stob Coire Sgriodain South Peak
Inverlair Lodge
Chno Dearg
Stob a^Choire Mheadhoin
Meall Garbh
Tulloch Farm
Loch Treig
Laggan Dam
Stob Coire Easain
Cille Choirille Church
Location names in dark blue are on the same original line.

A Base Camp

During the construction of the West Highland Railway one of the ^base camps^ was at the north end of Loch Treig, a location close to where the later Loch Treig Dam and Loch Treig Tunnel were built.

From this camp supplies were ferried by small flat bottomed ^puffer^ to the lochside locations where work proceeded. The line, going south, was slowly climbing to the summit at Corrour Summit, locations further south needing aerial ropeways to reach the works area from the lochside - by the south end of the loch the line was 450 ft above the water level.


07/08/1932West Highland Railway
Loch Treig Tunnel and diversion opened. The line was re-aligned at a higher level as the Loch became a reservoir, part of the Lochaber Aluminium Works scheme.


All Stations to Mallaig!: West Highland Line Since Nationalisation
Argyll and the Highlands Last Days of Steam

Argyll and the Highlands' Lost Railways

Ben Nevis and Fort William, The Mamores and The Grey Corries, Kinlochleven and Spean Bridge (OS Explorer Map)

History of the Railways of the Scottish Highlands: West Highland Railway v. 1

History of the Railways of the Scottish Highlands: West Highland Railway v. 1

Iron Road to the Isles: A Travellers and Tourist Guide to the West Highland Lines

Iron Roads to the Isles: A Travellers and Tourists Souvenir Guide to the West Highland Lines

Mountain Moor and Loch on the Route of the West Highland Railway

On West Highland Lines

Railway World Special: West Highland Lines

Rannan Rathad Iarainn nan Eilean =: The West Highland Line

Road To The Isles Dvd: Part One The West Highland Line Between Crianlarich to Fort William, From the Drivers Cab Of A Class 37, With The Caledonian Sleeper
The Mallaig Railway: The West Highland Extension 1897-1901 (RCAHMS Broadsheet)
The New Railway: The Earliest Years of the West Highland Line

The Story of the West Highland

The Story of the West Highland: The 1940s LNER Guide to the Line

The West Highland Railway

The West Highland Railway (Railways of the Scottish Highlands)

The West Highland Railway 120 Years

Trossachs and West Highlands: Exploring the Lost Railways (Local History Series)

Victorian Travel on the West Highland Line: By Mountain, Moor and Loch in 1894

Walks from the West Highland Railway (Cicerone Guide)

West Highland Line: Great Railway Journeys Through Time

West Highland Railway
West Highland Railway (History of the Railways of the Scottish Highlands v. 1): West Highland Railway v. 1
West Highland Railway: Plans, Poltics and People