The Westport Railway Workshop (Former) is a reminder of the importance of rail transport on the West Coast during the late nineteenth and early twentieth centuries. Early improvements to the transport system were a key to the area's successful development. Increasing understanding of the potential wealth in extensive deposits of high quality coal north of the Buller River made the Nelson Provincial Government eager to encourage its extraction. In 1871 they requested central government to provide a railway linking the coal fields with the port at the mouth of the Buller River. Although they were given a positive response no action was taken until central government undertook its own investigations. With new coal discoveries continually being announced and coal from the region sold profitably in Wellington the decision to build the Mt Rochfort Railway was confirmed. The route was surveyed and prepared, equipment ordered from London in January 1874 and in July the first sod was turned. The first section was completed to Waimangaroa in 1876 and to Ngakawau by September 1877. A railway station had been built in Westport in 1874 and from the end of 1875 passengers and freight was carried as far as the line then extended. The private company mining at Waimangaroa built a branch line to their nearby site to provide direct access for their output. In 1878 the Westport Colliery Company was formed, securing leases for the vast coal fields on the upper Mt. Rochfort plateau. They extended the branch line to Conn's Creek, the terminus of the famous Denniston Incline which was completed in April 1880. The remarkable self-activating rail system enabled great quantities of coal to be brought down a precipitous slope and readily dispatched to the port. The rail route and land at the port was gazetted in September 1881 for railway purposes. By this time, with several mines in full production, vast amounts of coal were transported directly to the wharf. Such a transport system was of vital importance to the economy of the isolated Westland area and a large supportive rail complex developed adjacent to the port. Work to establish this facility at Westport represented a large financial investment by the Railways at this time of growth for New Zealand's rail network. (In 1880, despite the great impact made by the Mt. Rochfort Railway, a Railways Commission doubted the wisdom of the expenditure.) The railway provided a busy passenger service as well as carrying freight to and from the northern coastal region of the Buller district. Although coal was the principal export the port handled a wide range of products, the bulk of which was brought to, or taken from the wharf by rail. The rail service was essential to the region's viability. A major workshop where engines and rolling stock were repaired and maintained was an essential component of the busy rail complex at Westport. Over the years New Zealand's rail network was sustained by thirteen workshops, only two of which continue to operate. In the South Island there were five, with one at Greymouth as well as the one at Westport because the lines were not initially connected. Some of these workshops not only did maintenance work, they also constructed locomotives in the first decades of rail expansion. The first government railway workshop was established here in 1880 in Adderley Street, adjacent to the wharf. Although no engines were built here, wagons and other rolling stock were constructed over the following years. By 1895 coal output had increased and in that year, from the Denniston mine alone, 215,770 tons (218,232 tonnes) of coal were brought down the incline and railed to the wharf at Westport. In 1897 the workshop and some neighbouring buildings were burned down and though most of the machinery and several locomotive engines were saved, this was a major loss and a new workshop building was an immediate necessity. The present building, erected soon afterwards, incorporated a heavy stone firewall along the eastern, or Adderley Street side. More usually, railway workshops were constructed of corrugated iron over timber framing and this replacement stone and corrugated iron building was probably built to provide greater longevity because of the recent experience of destruction by fire. The new workshop, covering 39 x 24 metres, was described as 'most substantial and fitted throughout with up-to-date lines' and perfect lighting arrangements. A 10-horsepower horizontal steam engine drove the lathes and numerous other machines, operated by about 50 staff. A further 17 staff were employed to run the locomotives. At the time of the workshop's replacement a new station was built, as the original building was no longer large enough. During the 1929 Murchison earthquake, part of the southern section of the stone wall collapsed. As a result, about 40 percent of the wall was demolished and replaced with a timber and corrugated iron wall, while part of the roof was also rebuilt. However, all ten of the distinctive 'ripsaw' roof sections survived on the western or wharf side. Over the years, the rail linkages were progressively extended down to Inangahua, Greymouth and beyond. The workshop was kept busy providing the necessary items for these developments. In 1923 completion of the Otira tunnel provided the final link to Canterbury and Lyttelton, allowing coal to be transported for export from there. Initially there was only a slow reduction in traffic to Westport for shipping and the load of work carried out at the workshop continued in the following decades. In the 1970s production of four wheeled wagons designed to carry motor vehicles (class MCC) were a feature from the workshops at both Greymouth and Westport until 1986 when the Greymouth workshop closed. Use of road transport increased, reducing the passenger and freight traffic centred in Westport. As the amount of local engineering and maintenance work declined, the workforce was reduced and by 1994 with the rail network now controlled by Tranz Rail Ltd. the workshop was no longer required. It was leased to Westland Farmers who sub-leased the workshop to Adco. The current lessees removed the railway lines and filled inspection pits that remained in the floor on the western side. Adco use the building to manufacture concrete mixers, gardening equipment etc there for nation-wide distribution.

The workshop is sited on railway land alongside the railway line which extends out along Westport's wharf. Due to the closure of the buildings associated with rail maintenance, the workshop is now flanked by more recent buildings with a variety of uses including storage and wharf-related activities. None of these buildings which closely adjoin the historic workshop have similar heritage significance. The workshop is approximately 40 by 24 metres long, on a north-south axis, roughly parallel with the wharf and river. Construction is mainly corrugated iron over timber framing, but there is a heavy stone load-bearing wall along the eastern or Adderley Street frontage. The latter appears to have been made from dressed river boulders, mostly granite and gneiss with some sandstone, held together with mortar of unknown composition. The stone wall is just 25 metres in length, the southern portion having been demolished. It now has just six 'teeth' or gable ends for the 'ripsaw' profile roof, compared with ten along the corrugated iron western or railway side wall. The roof ridges run east and west. Below each section on the eastern side is a corresponding window in the stone wall. Each opening is slightly arched, with a lintel of stones set on their edges. The original sashes have been replaced with opaque plastic, protected by wire netting. There are fewer windows on the western side, but they include what could be an original multi-paned sash at the northern end. The original skylights on the vertical planes of the 'ripsaw' roof have also been replaced with plastic. They face south, possibly indicating a northern hemisphere design and orientation, but more probably to prevent glare from the direct sunlight inside the workshop. Internal features are heavy beams and posts, probably necessary to support travelling hoists and other equipment used for lifting and moving heavy components. All that remain in the way of that sort of equipment are wall-mounted swinging arms that carried chain hoists. The huge 19th century lathe has been replaced by a modern machine in the same position. There is evidence of a large doorway in the northern wall, now filled in, but a corresponding door in the southern wall is still used. Inspection pits in the floor have been filled in and railway lines removed.