Big Hill Cutting, Hilltop, NSW

Big Hill cutting which runs through Saddleback Ridge between Balmoral and Hill Top was once the deepest cutting in Australia at 24m, (Bethungra, NSW and Windmill Hill, WA are deeper). Originally planned as a tunnel on a gradient of 1 in 33, it instead had to be a cutting, because in a tunnel the smoke belching from the steam engines on the upward climb would have suffocated train crews and passengers.



Excavating through solid sandstone using hand tools and dynamite, work crews toiled to create the 78 foot (23.4 metre) cutting. Work stopped for a time after an explosion killed two workers. Their names are carved in perpetuity in the rock face. This cutting was indeed a feat of human endeavour.

A rock-cut inscription dated 1863, commemorating the deaths of two men in the explosion during the excavation of the cutting, north of Hill Top, is considered one of the oldest in Australia. Big Hill cutting is on the Picton–Mittagong loop line in the NSW Southern Highlands.


North of Mittagong looking south with 1919 deviation on left, the Loop Line joins it on right

The Picton–Mittagong Loop Line

After years of discussion and planning, a railway from Sydney to the south was completed as far as Picton by 1863, with contractors ready to progress the line on to Nattai (Mittagong) and to Goulburn and beyond. Initially a private undertaking, the southern railway was taken over by the NSW government and it appointed John Whitton, from the UK, as Engineer-in-Chief. He would serve for 33 years, earning the title of 'Father of the Railways'.

For the Picton-Nattai section Whitton selected the least expensive route which traversed the ridge, flanked by deep gullies, on the western side of the Bargo River. He thus avoided the more direct ridge carrying the Great Southern Road (now Old Hume Highway) that would have required bridges and tunnels beyond the means of the burgeoning colony. However, the direct route was followed when duplication of the whole line from Sydney to Albury was undertaken from 1914, and the original line became referred to as the Picton–Mittagong Loop Line.

Whitton's route through the undeveloped upland south of Picton soon became dotted with the tents of navvies' encampments, dirt tracks and cart roads. The line ran north-northwest from Picton, over the Picton Viaduct, across the Great South Road before heading northwest. It then headed west-northwest through a 180-metre tunnel in the Redbank Range.



Stations were constructed at Redbank (1885), Couridjah (1867), Buxton (1893), Balmoral (1878), Hill Top (1878), Colo Vale (1883) and Braemar (1867). There were a number of smaller stops, sidings and passing loops along the line, as well. North of Hill Top, the cutting through Big Hill was for many years the deepest in Australia. The rock-cut inscription dated 1863, commemorating the deaths of two men in an explosion during the excavation of the cutting, north of Hill Top, is considered one of the oldest in Australia. For a time this Loop Line was the main south from Picton to Mittagong, Via Thirlmere, Couridjah, Buxton, Hill Top and Colo Vale. To service the line, Picton became a busy station with a locomotive depot for bank engines, dormitories for train crews, and goods sidings.


Gatekeepers cottage, Picton

While gently curved, the line had gradients as steep as 1 in 30. It was also a single-track line, and even though deviations were constructed between Hill Top and Colo Vale to ease grades, these factors combined to create a bottleneck, as rail traffic increased. In July 1919 a new double track alignment with ruling 1 in 75 grades between Picton and Mittagong via Bargo opened. The original proposal was for the line to be shifted considerably further eastwards from Appin to Bargo avoiding Picton. This was strongly opposed in Parliament by Picton local interests, hence the 180° curve that circumnavigates the town.

The old line, now renamed the Loop Line, continued to be served by passenger services until August 1978. Most services were operated by 30 class locomotives and later CPH railmotors, although there was a Sunday evening service to Sydney hauled by main line locomotives as recently as 1973.

From the 1960s the line was popular with steam hauled specials, and was the preferred route for most journeys where they could operate without inhibiting regular services. Following it relocating to Thirlmere, in June 1976 the New South Wales Rail Transport Museum (NSW Rail Museum) commenced operating steam services on the line between Picton and Buxton.

The line remained open throughout, although by the 1980s the Buxton to Braemar section saw little use. CPH railmotor CPH22 ran a trip to Braemar and three shuttles between Braemar and Hilltop on 31 May 1987, before a trestle bridge between Colo Vale and Braemar suffered flood damage, resulting in the line being divided into two separate branches in September 1987.

The line eventually closed in the late 1980s, but a small section between Picton and Buxton is still used by the NSW Rail Museum. Following the Department for Transport calling for expressions of interest for using a number of disused lines, the New South Wales Rail Transport Museum was granted a lease over the Picton to Buxton section in 1993.