Track

A prime consideration in the building of the line was the weight of materials, which had to be brought to the estate by small coastal steamer. Rail weight in particular was thus kept to a minimum, the rail and related ironmongery being imported from Glasgow.

The main line and the Clachbeg branch are laid with 25-pound, 15' long rails on locally-produced wooden sleepers; many sidings still use the original 12-pound rail in 9' lengths, whilst the Bealach line is laid with 12-pound rail on wooden sleepers, using 15' rails. The Woods line has a mixture of 15' 25-pound and 12-pound rail on wooden sleepers, and uses 9' prefabricated rail panels for temporary spurs.

The 12-pound rail is rated for axle loads of up to 3 tons, and the 25-pound rail for 5 tons; due to the sleeper spacing the permitted axle load on the branches to Woods and Bealach is 1½ tons, while the main line and Clachbeg branch permit 4 tons. The axle load for the gold mine siding is restricted to 1½ tons (its 12'-3" radius curves limit wheelbase too, to 2'6").

Rails are spiked directly to the sleepers without tieplates with two spikes on the outside of the rail and one on the inside; turnouts have tieplates for the switch rails. Spikes are 3/8" × 3½" for the 12-pound rail and ½" × 4½" for the 25-pound rail. Rails are fished together using 16" fishplates with four 5/8" holes at 4" centres, bolted with ½" × 1¾" track-bolts. The fishplates of the main and branch lines are re-greased annually in the summer months.

Crossing flangeways are 1 3/8".

Wooden sleepers are 4'-6" long, 6" wide and 4" high; turnout sleepers are 8" wide and up to 9' long. Sleeper spacing on the original line was at 3' centres, and some sidings are still laid at this spacing. As rails frequently distorted, subsequently during maintenance the main line and the Clachbeg extension were relaid with a seven sleepers per 15' rail spaced at 12½"–2'7"–2'7"–2'7"–2'7"–2'7"–12½" centres and on bridges eight sleepers spaced at 1'–2'2"–2'2"–2'2"–2'2"–2'2"–2'2"–1' centres; turnout sleepering is also spaced at around 24" centres.

Guard-rails are fitted across bridges at 3" flangeways.

Curves

In the sidings and on the lines to Woods and Bealach radii of just 12'-3" are commonplace, however the main line connecting Kinlochy to Strathan is laid with 2 chain minimum radius (with the exception of the tight bend at Falls and the bridge at Kinlochy, which both have 1 chain radius curves).

The running line to Clachbeg has a ½ chain minimum radius.

Loading gauge

The clear way is 6'-8" wide and 10' high, giving a 6" clearance around all sides of the rolling stock. On curves of over 2 chains radius this is widened to 7"; if the radius is under 2 chains then this is widened to 8".

Platforms are allowed to encroach 3" into the loading gauge; their height may be up to 1'-8". Passenger platforms are frequently located on sharp curves and encroach up to 6", however in such cases they are limited to 6" high and wagons overhang them.

Track centres are 8' for sidings and passing loops.

Civil engineering

There are few significant civil engineering works, as might be expected on such a light railway: the stone pier at Kinlochy, the two bridges over the Allt Garbh—one by Kinlochy, the other near Strathan—and a wooden bridge at the entry to Clachbeg; further there are many culverts. The river bridges are used by foot traffic too.

The ruling gradient is 1 in 18 (influenced by Works Engineer John Hurt’s experience on the Darjeeling Himalaya Railway) and the rolling gradient is 1 in 20; the short climbs out of Kinlochy and Mains are 1 in 25; the Woods, Clachbeg and Bealach spurs both include frequent 1 in 20 climbs.

The ruling vertical radius is 40'; in practice the vertical curve is made over the longest permitted wheelbase, which is 11' on the main line and 4' elsewhere.

Earthworks are generally minimal. There are no tunnels, and the only deep cutting is at the approach to Clachbeg where the line passes between Creag Ór and Creag na Còsaig and some blasting was required.

Ballasting is minimal, but is actively maintained on the main line, and as required on the other lines; the Bealach extension requires repair every spring.