The Biggest Little Railway in the World

The project took months of planning. It was described as an operation of fiendish complexity.[2] Calls were made for the 56 volunteers determined to be needed for the project.[6] There were planning meetings at the start of each day.[2] Some disagreements occurred but were overcome by a spirit of gusto and camaraderie.[2]

Engineers Claire Barratt and Hadrian Spooner who had worked on engineering projects such as Scrapheap Challenge and Salvage Squad also acted as part of the credited professional team.[3]

A team of 56 volunteers constructed and operated the line with help from local volunteers.[4]

The local community also assisted the enterprise at various points including the Inverness and District Model Railway Club provisioning a model station and castle for the train's arrival.[1]

The Invergarry and Fort Augustus Railway, opened by the Victorians in 1903 and closed in 1946, had connected to the main line at Spean Bridge. It was speculated the ultimate aim was the same as the BLR's, to reach Inverness though the attempt was abandoned.[2] In 2009 James May attempted to beat the longest OO Gauge record.[7]

Finding suitable track. Conventional track cost about £7 per metre making the 70 miles unfeasible from a cost viewpoint alone. Without a viable track solution the project would have been a nonstarter. A suggestion to extrude the track meant 32 tonnes of recycled PVC could be pushed through dies for 40,000 straights and curves which solved the problem economically and effectively and enabled the scheme to pass beyond the idea stage[5]

The BLR overcame the obstacles of main line railway swing bridge followed by a road crossing at Banavie by construction and operation of a derrick and train ferry to assist over a water hiatus.[8]

The railway needed to cross the canal at Laggan 57.033°N 4.813°W / 57.033; -4.813. The A82 road at this point uses a swing bridge and it was determined The Biggest Little Railway in the World would not use this. The solution was to use a truss bridge. The bridge was later re-used at the Caledonian Helix.

Crossing the Aberchalder Spillway 57.095366°N 4.741556°W / 57.095366; -4.741556, which was bridged with a 60 metres (200 ft) viaduct. The team are outraged when Dick Strawbridge insists the Battery Electric Little John relief locomotive is used for the iconic crossing.[9]

The feature was initially variously termed a ford or a weir by the project whereas spillway seems correct, the weir being further to the southwest.[10][11]

The railway faced the difficulty of bridging a gap over Inchnacardoch Canyon 57°09′14″N 4°41′03″W just north of Fort Augustus. The Great Glen Way used a footpath unviable for the railway around this feature. A suspension bridge was not an option as a curve was needed between the entry and exit points. Uneven ground contours increased the challenge. The solution chosen was a trestle bridge. The trackbed was secured to a series of connected bespoke a-frames giving great strength while using a minimal quantity of wood. The entrance and exit points were on a different levels with a smooth gradient required throughout. The construction team used Archimedes' principle and a long clear tube filled with fluid to establish a datum height across any two points on the site so a consistent gradient could be calculated. When the build was underway it was discovered the exit would require a curve of too tight a radius for a train to circumnavigate. The solution was to extend the bridge further to a different point where a suitable curve could be achieved on exit. The resulting structure was a 905 inches (23.0 m) reverse curved wooden swerving trestle bridge which proved even able to support a 65 kilograms (143 lb) man. Silver Lady negotiated the Bridge successfully with careful driving by Andy though the lack of a parapet could have proved disastrous in the event of a derailment.[9]

Inch mountain is the BLR name for the Great Glen Way's ascent to height in Inchnacardoch forest. 57°09′14″N 4°41′03″W The incline exceeds even the 17% maximum gradient of Silver Lady. As the route could be divided into a small number of relatively straight sections a counterbalance railway solution was chosen. This is a form of cable railway with a train of near equal weight descending on a parallel track attached by a cable through a pulley at the top of the climb. In this implementation a sister locomotive Silver Lady II was used as counterweight and the locomotives achieved sufficient adhesion to bring Silver Lady up the inclines.

The challenge on Invermoriston Mountain 57°13′03″N 4°36′24″W was to overcome a series of zig-zag gradients. The solution chosen was to construct a hand cranked winch that could be attached to the locomotive via a cable. The navvies found an efficient method of track construction at this site by getting quad bikes to drop bundles of track at the top of a slope allowing the navvy to simply join lengths of track at the top in a sitting position and gravity feed the track down the slope. In practice the winch system proved to be very effective.

The ascent of Creag Nay 57°22′N 4°25′W presented issues of curling tracks, poor terrain and steep ascents. It was decided a rack and pinion system would be most effective. Flexible cogged belt was stuck on a wooden baton which was glued to the centre of a track. This engaged with a cog wheel fitted on the axle of the Silver Lady. The navvies completed the construction successfully, albeit the wet climatic conditions interfering with the adhesive. Testing with a supplied gear wheel proved successful but unfortunately there was no testing with a real locomotive before the first train came to pass. When tried operationally it was found that while successfully causing the locomotive to climb the gradient the centre tooth belt was set too high meaning the locomotive was not properly resting on both rails and having an extreme propensity to toppling over. The belt was therefore ripped out and an improvised winch system based on an electric drill used to assist the locomotive up the slope.

At the point the Great Glen Way rejoins the Caledonian Canal on the outskirts of Inverness there was 5 metres (16 ft) near vertical climb in a restricted space. This was solved by a spiral loop solution matching Silver Lady's 2 ft minimum curve radius and restricting to an 8% maximum gradient. The solution also re-used the truss bridge from the Laggan Locks canal crossing.

Silver Lady[12]
Silver Lady
Type and origin Power type Steam Builder Roundhouse Engineering Co Ltd, Doncaster.
Specifications Configuration: ​  • Whyte 0-6-0T Gauge 32 mm (1.26 in) 45 mm (1.772 in) convertible Minimum curve 2 feet (0.61 m)[13] Length: ​  • Over beams 315 millimetres (12.4 in) Width 125 millimetres (4.9 in) Height 160 millimetres (6.3 in) Loco weight 3.3 kilograms (7.3 lb) Fuel type Gas Boiler pressure 40 psi[14] Valve gear Walschaerts (simplified)
Performance figures Maximum speed 3 miles per hour (4.8 km/h)+
Career Operators BLR Preserved 1
Additional Specifications Suspension fullysprung Control R/C Max. forward gradient 12% Max. curve gradient 8% Max. reverse gradient 17%

The Silver Lady Class locomotive was a development of the Lady Anne Class but featuring a sprung chassis, water top up system and other detail refinements.[12]

Silver Lady completed the run from Fort William to Inverness whilst being relieved by Little John for a couple of sections.

An additional Silver Lady class locomotive was used in support. It was fitted with patterned wheels needed for extreme climbing performance. As well as use on the counterbalance climb it was used as the relief locomotive on hill climbing sections and where urgent repairs were needed to the main locomotive.[14]

The Lady Anne Class was a classic design and the precursor to the Silver Lady Class.

The Lady Anne was used for driver training and evaluation at the main depot. It also participated in evaluating prototype design testing for the Caledonian Helix and stood in for Silver Lady on a photoshoot of the Aberchalder Viaduct.[14]

The Little John Class is a 0-4-0 battery-electric locomotive modeled on a diesel shunter.

Little John was the yellow class leader that substituted for Silver Lady while she was undergoing service or when steam support engineers were not available on the longer overnight catch-up runs. Little John was also involved in Special ops support operations such as filming from a locomotive driver's eyeline.[14]

This grey Little John class locomotive was used to test the Inchnacardoch Canyon trellis.[15]

Wooden styled coaching stock operated near Fort William only. At least one coach was built by volunteer Paul. The coaches were susceptible to blowing over in the wind, throwing the whole train onto its side. Additional ballast weights placed under one coach may have contributed to the axle dislocation and the coach becoming unserviceable.

The tracklaying teams were challenged to try to lay an average of 5 miles (8.0 km) of track each day.[3]

The original scheme was to share locomotive driving amongst the volunteers, however as Silver Lady began to fall critically behind schedule it was deemed necessary to predominately use a top-link team composed of live-steam experienced people who could operate the locomotive smoothly and efficiently.[5][1][14] This included Alan, a professional train driver, model rail hobbyist and volunteer fireman on the Severn Valley Railway,[16][1] and Cameron, engineering ambassador alumnus of St Helens College, miniature steam train driver, and founder of his own heritage engineering restoration business at age 17.[17][18]