Messrs Peto, Brassey and Betts, contractors with extensive worldwide experience in railway construction and builders of Section 1, were awarded the contract on 27 February 1865 for a sum of £515,000.

The Queensland Government's immigration agent advertised in Great Britain and Germany for railway workers, offering free passage on the Black Ball shipping line to artisans such as excavators, bridge carpenters, masons and bricklayers.

Such work in difficult terrain carried with it a high degree of risk and a number of work-related injuries and deaths occurred along the line during construction.

The makeshift nature of the camps led to inadequate sanitation with typhoid and diphtheria causing the death of a number of infants and young children in 1866 and 1867.

Numerous visitors to the Darling Downs in the late nineteenth and early twentieth centuries marvelled at the engineering and scenic qualities of the Main Range Railway.

Until road transportation began to dominate in the twentieth century, the railway was intrinsically associated with the development of pastoral, agricultural and mining industries, closer settlement and the growth of townships on the Darling Downs and south western Queensland.

Despite the advent of more powerful locomotives during the nineteenth and twentieth centuries, the combination of sharp curves, steep grades and tunnels created difficult conditions for crews.

Railway workers needed to ensure adequate supplies of coal and water to negotiate the crossing and banking engines were employed between Murphy's Creek and Toowoomba to assist ascending trains.

[1] Since its opening in 1867 the Main Range line has sustained a high level of usage with various maintenance and upgrading works ensuring its continuity as a vital transport link.

A report of the Main Range Railway line in March 1867 included a description of the brick abutments and stone facings of the overbridge on the road to Highfields.

[1] Between 1899 and 1902 the track was strengthened to support 12 long tons (12 t) axle loads and realigned to eliminate curves below a five chain radius, while the inadequate original iron girder bridges on timber piers were replaced with embankments and culverts.

[1] From the early 1900s the picturesque surrounds of Spring Bluff became a popular local destination for recreation and leisure, with an entertainment shed provided on a rise behind the station between 1907 and 1911.

During the 1930s and 1940s Station Master Ralph Kirsop, his wife Lillian and night officers undertook extensive improvements to the gardens, creating flower beds terraced with blue metal stone.

[1] In the 1860s, the ambitious construction of the Main Range Railway provided the colony of Queensland a critical transport link for the export of goods from its interior.

Responding to the terrain, numerous built features including tunnels, cuttings, culverts, bridges, embankments and stabilizing works occur along the extent of the railway.

Constantly changing and frequently spectacular vistas of steep timbered hills, gullies and distant ranges extend south east to the coastal plain.

At varying depths beneath the rail, they direct water from the north side of the track, passing under the length of the railway and parallel access road and drain to the south east.

[1] Located between the trolley shed and the platform of Spring Bluff, a wide drain with rendered stone walls passes underneath the track.

[1] Between a large, tiered modern cutting of shotcrete (known as Moggill's Wall and not of cultural heritage significance) and the entrance to Tunnel 3 (144.5 kilometres (89.8 mi)), a steep, high and long rock face incorporates a number of features.

After passing a high tiered face of lightly coloured and loosely packed rock, a small low bank running parallel to a short, straight section of rail between two curves incorporates a number of features.

[1] Between the 157–158 kilometres (98–98 mi) posts, close to the summit of the range and running parallel to a section of check-railed curving track is a retaining wall.

The structure is detailed with prominent cornices at the bases of the arches and incised lines on the spandrel walls of a form similar to the joints that would occur in a stone bridge.

The key features of the site are located on a series of terraces cut into the escarpment of the main range, on the north side of the railway, surrounded by native vegetation composed predominantly of open eucalypt forest.

A station building and platform, railway residences, timber pavilion and other built structures are placed among expansive landscaped gardens and open grassed areas.

Prominent plantings include a large clump of bamboo next to the station building and a nearby London Plane tree (platanus acerifolia) (1870) with a commemorative plaque at its base.

A second, unhooded window of glass louvres is partially obscured by a corrugated iron water tank, set on high timber stumps and base.

An immense undertaking for its time (1865-1867), involving a large workforce and a dramatic alteration of the landscape, the Main Range Railway is one of Queensland's most significant early public works.

Along the route engineering features responded to challenging and variable terrain, as demonstrated in the provision of nine tunnels, numerous culverts, cuttings and embankments, and extensive use of curved track.

Constantly changing and frequently spectacular vistas of steep timbered hills, gullies and distant ranges extend south-east to the coastal plain.

Over challenging and variable terrain and an incline close to 365 metres (1,198 ft), the Main Range Railway demonstrates the extent of engineering necessary to construct the route, as evidenced in the substantial use of tightly curved track, tunnels, culverts, cuttings, embankments and bridges.