Railway Bridge and Viaduct

Parnell Rise, Mechanics Bay, Auckland

  • Railway Bridge and Viaduct.
    Copyright: NZ Historic Places Trust.

List Entry Information

List Entry Status Listed List Entry Type Historic Place Category 2 Public Access Private/No Public Access
List Number 7585 Date Entered 14th April 2005

Locationopen/close

Extent of List Entry

The registration includes the land in CT NA83B/527, part of the land in CT NA90B/394, and CT NA637/246, and part of the Parnell Rise and Carlaw Park Avenue road reserves in between these titles (as shown in on a map in Appendix 2 of this registration report), and the bridge and viaduct, its fixtures and fittings thereon. It excludes the railway track and other items of working railway equipment. A 10m section of railway embankment between the northern abutment of the bridge and the batter of the Stanley Street extension is included within the registration proposal, as is a 10m section of embankment to the south of Carlaw Park Avenue.

City/District Council

Auckland Council (Auckland City Council)

Region

Auckland Council

Legal description

Part of Lot 1 DP 151550 (CT NA90B/394); Lot 4 DP 140374 (CT NA83B/527); part of Pt Lot 3 DP 22823 (CT NA637/246); part of Parnell Rise road reserve between Lot 1 DP 151550 and Lot 4 DP 140374; and part of Carlaw Park Avenue road reserve between Lot 4 DP 140374 and Pt Lot 3 DP 22823

Location description

The bridge is located near the western end of Parnell Rise, between the Stanley Street and The Strand turnoffs. The associated viaduct extends from the southern side of the Parnell Rise road reserve to the eastern side of the Carlaw Park Avenue road reserve.

Summaryopen/close

The Railway Bridge and Viaduct at Mechanics Bay, Auckland is believed to be the earliest bridge linked with steam railways to survive in the North Island. Originally constructed in 1865-1866, it formed part of the ill-fated Auckland to Drury Railway project, which proposed to link the growing colonial settlement at Auckland with sources of coal in the Waikato. The route was also intended to provide a supply line to British military forces and early settlers after the colonial invasion of the Waikato in 1863-1864. The first part of the project involved constructing a length of track between the industrial and commercial suburb of Mechanics Bay with the outlying settlement at Newmarket. The works were to include a stone bridge and viaduct at Mechanics Bay, as well as cuttings and a tunnel beneath the Auckland Domain. In an attempt to save money, the contract was offered to a local scoria carter, Peter Grace, who had little previous experience of undertakings on this scale. The overall project was the largest carried out by the Auckland Provincial Council by that time.

Probably designed by the main project engineer, James Stewart, in association with Samuel Harding, the structure consisted of a bowstring bridge and a viaduct over Parnell Rise, all resting on large basalt piers. Carried out in a monumental style for the period, the ashlar masonry was mortar-bonded, concealing a rubble backing. Work on the structure was probably finished in October 1866, by which time overruns on time and budget had forced the rest of the project to be cancelled. Not having been connected to central Auckland across the waters of Mechanics Bay, the structure remained unused as an expensive white elephant until the public works policies of Julius Vogel (1835-1899) in the 1870s caused the Bay to be reclaimed and a line from Auckland to Onehunga completed. Small modifications were made to the bridge at this time. When completed, the line was the first of Vogel's railways to be operational and the earliest to be run directly by the General Government.

Slight alterations were made to the bridge in the 1890s, when some of the masonry piers were raised in height. More substantial modifications occurred in 1908-1909, at which time the entire superstructure was replaced. The new superstructure incorporated a bridge of Warren truss type, while two of the piers beside Parnell Rise were removed to enable the road to be enlarged. The remaining piers and abutments were widened using an almost identical style of construction to the 1860s work. The works allowed for the installation of a wider, double-track line, and were completed at the same time that the main trunk line between Auckland and Wellington was opened in 1909. The structure has been comparatively little altered since that date and remains in daily use for rail transport, although no longer part of the main trunk line. The structure is considered to be important for its associations with New Zealand's transport and technological history, and has architectural and aesthetic qualities for its monumental nature and use of local materials, notably basalt. It also has archaeological value, retaining nineteenth-century fabric in its piers and abutments, and other archaeological material in its embankments.

Assessment criteriaopen/close

Historical Significance or Value

The bridge and viaduct structure at Mechanics Bay is particularly important for its association with the first steam railway project in the North Island, and the most ambitious construction project undertaken by the Auckland Provincial Government by the mid 1860s. The structure is closely linked to the desire by the Provincial authorities to expand Auckland's sphere of influence, at a time when the settlement was New Zealand's colonial capital. It is strongly connected with the Waikato Wars and an intent to expand exploitation of the region's natural resources. In 1873, the structure was part of the first operative 'Vogel Railway' in the country and the earliest line to be operated by the General Government. It was instrumental in the carrying out of an ambitious reclamation project, which transformed Auckland's central city landscape.

The structure also has historical value for being an integral part of Auckland's links with its hinterland until the 1930s, facilitating the 'opening up' of the countryside and allowing the city to expand and prosper. Alterations in the early twentieth century have significance for their connections with closer inter-city links between Auckland and Wellington and the completion of the North Island Main Trunk line.

Although largely concealed by advertising hoardings and surrounding buildings, the structure has some aesthetic value for its monumental appearance. The structure has archaeological value for its incorporation of significant fabric from the 1860s, which can reveal information about construction, quarrying and other techniques of production. The remaining abutments and sections of embankment are likely to cover evidence of earlier historical landscape use and environmental information.

The structure also has architectural value for incorporating recognisable remnants of early railway architectural design. It reflects the use of basalt as a local construction material in the early colonial era, and is one of comparatively few such structures remaining in inner Auckland. Although aspects of archaeological and architectural significance have been partly reduced by its incorporation of an early twentieth-century superstructure, the double-intersection Warren truss across Parnell Rise is an unusual survival in an urban context. Modifications to the stonework undertaken in the 1870s and early 1900s have been carried out in a sympathetic manner to the 1860s design.

The structure has technological value for retaining elements that are part of a major engineering achievement in New Zealand's early colonial history.

(a) The extent to which the place reflects important or representative aspects of New Zealand history

The place reflects important and representative aspects of New Zealand history, notably the development of rail transport and the role of provincial government. The structure'sThe earliest phase of construction illustrates a willingness common in pioneering times to embark on undertakings notwithstanding a lack of experience and shortage of resources. The structure is believed to be the earliest major railway bridge to survive in the North Island, and is particularly significant for reflecting the very first stages of rail transport in northern New Zealand.

(b) The association of the place with events, persons, or ideas of importance in New Zealand history

The structure is closely connected with important events in New Zealand history such as the Waikato Wars and subsequent European settlement of the Waikato, and the public works schemes of Sir Julius Vogel. It is connected with noted engineers, particularly James Stewart, Samuel Harding and John Coom, all of whom were employed by the Public Works Department during the formative years of its development.

(c) The potential of the place to provide knowledge of New Zealand history

Retaining fabric in its piers, abutments and embankments from the 1860s, the place has potential to provide knowledge of new New Zealand history through archaeological means, as well as through comparison with extensive surviving documentary material.

(f) The potential of the place for public education

As a prominent structure surviving in a public, central city location, the structure has considerable potential for public education about early colonial and later transport, the New Zealand Wars and Auckland's role as a major trading centre.

(g) The technical accomplishment or value, or design of the place

As a working structure with its origins in the 1860s, the piers and abutments of the structure represent a considerable accomplishment in early New Zealand structural engineering.

(i) The importance of identifying historic places known to date from early periods of New Zealand settlement

A significant amount of the structure dates from the early colonial period, when Auckland was the capital of New Zealand.

(j) The importance of identifying rare types of historic places

Nationally, the structure is one of few surviving railway structures originating in the 1860s, and one of even fewer still in use. It is one of comparatively few bridges of any type originating from that period.

(k) The extent to which the place forms part of a wider historical and cultural complex or historical and cultural landscape

The structure forms part of a railway landscape that incorporates a cutting at the base of Parnell Hill and the Parnell tunnel, built as part of the same contract in the 1860s. Other elements of the historic landscape survive in the immediate vicinity, notably the Swan (now Strand) Hotel, whose door sill was used to surveycreate the levels for the bridge at the time of its initial construction.

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Construction Professionalsopen/close

Stewart, Francis Drummond

Stewart was born at Southland and educated at Otago Boys' High School, the University of Otago and Auckland University College.

He worked initially for H McDowell Smith in Dunedin and from 1926 to 1936 he was staff architect to Fletcher Construction Company. During this time he was responsible for the Station Hotel, Auckland, Brandon House, Wellington (1931), Nimmo's Building, Wellington (1929), and in conjunction with Herbert Hall of Timaru he designed the Chateau Tongariro (1928).

He joined the Housing Department (later incorporated into the Ministry of Works) in 1937 and held various senior positions over the years. He was appointed Assistant Government Architect in 1952 and represented the Ministry and the Architectural Division at meetings of the Cabinet Works Committee. He held this position until his retirement in 1968.

Stewart was admitted as an Associate of the New Zealand Institute of Architects in 1936, and was elected a Fellow in 1958.

Harding, Samuel

Samuel Harding

Samuel Harding (1822-1907) was born in Limerick where he trained as an engineer and surveyor. On arriving in New Zealand, he entered the service of the Auckland Provincial Government. With James Stewart, he was engaged in the survey of a proposed railway from Auckland to Drury in 1862. After the hiatus caused by the outbreak of war in the Waikato, both men again worked together supervising the construction of the line until worked stopped in 1867 through a lack of finance.

Harding was employed with Henry Wrigg in 1871 surveying the railway route from Auckland to Mercer as an alternative to the Auckland to Tuakau line that was originally proposed. Harding was appointed Resident Engineer in the Public Works Department at Kaipara in 1872, where he was in charge of the construction of the Kaipara railway line. He later went into private practice in Auckland, latterly with his son Samuel John Harding, who after 1894 went on to work extensively on projects involving the design and construction of railways.

Coom, John

John Coom

John Coom (1844-1921), the first Chief Engineer of the New Zealand Railways, was born in Cornwall where he trained as a civil engineer. In 1870 he served as Engineer to Malling (Kent) Highway Board. In 1872 he was assistant engineer on Liskeard-Coradon Railway, Cornwall Minerals Railway, and on county bridges and drainage projects before emigrating to New Zealand. In 1876, he was appointed Surveyor to the Public Works Department in Wellington, and was involved in surveying. Nelson and Blenheim connections to Christchurch and West Coast, via Tarndale and Tophouse. In January 1879, he became Assistant Engineer, and by April 1881 was Resident Engineer engaged on construction of the Wellington to Johnsonville railway (afterwards the Wellington to Manawatu railway).

Towards the end of 1881, Coom transferred to the Railways Department as Resident Engineer Auckland, subsequently becoming Resident Maintenance and Locomotive Engineer there in 1884. In December 1891 he was the Resident Engineer in Invercargill, and after about a year as Acting Chief Engineer in Wellington, again returned to Auckland as Resident Engineer. In August 1899, he became Chief Engineer, having also served as Resident Engineer in Dunedin and Inspecting Engineer in Wellington. Coom retired from his position as Chief Engineer in 1908.

Grace, Peter

(1865-1866) register number 7585

Railway Department

No biography is currently available for this construction professional

Additional informationopen/close

Historical Narrative

Early Railways in New Zealand

The first railways in New Zealand were built in the South Island. As early as 1859 the Canterbury Provincial Council reserved strips of pastoral and agricultural land to provide for future railway development. Canterbury's railway lines carried the first steam locomotive in regular service, providing an early nucleus for the development of a nationwide rail system. The earliest steam railway linked Christchurch and Ferrymead, and opened for traffic on 1 December 1863. Further south, the Southland Provincial Council had authorised construction of a 29km (18 mile) line from Invercargill to Winton in 1863, which was completed towards the end of 1869. Another line, between Invercargill and Bluff, opened in 1867.

The Auckland and Drury Railway (1865-67)

The earliest steam railway construction project undertaken in the North Island was the Auckland to Drury line. Initiated by the Auckland Provincial Council in the early 1860s, this was intended to run from the centre of Auckland to Drury - a distance of 35km - with a branch line to Onehunga. Two factors were responsible for the project being planned. In the first instance, coal mined in Drury was urgently needed for the development of industry in the Auckland, the colonial capital, which was importing £30,000 worth of coal from New South Wales. At the same time, fear of unrest from the King Movement in the Waikato presented a military reason for building an efficient transport system for soldiers and supplies. Drury was located on the southern fringe of the land controlled by the colonial authorities and was to form a launching pad for efforts to invade the Waikato in the Second New Zealand - or Waikato - War (1863-64). The project was considered in the mid 1860s to be the largest undertaken by the Auckland Provincial Council.

In February 1862, the Auckland Provincial Council authorised £500 for a survey to be carried out by the noted surveyor Charles Heaphy, and engineers James Stewart and Samuel Harding. Two years later, a Railway Commission was appointed and authorised to construct a £100,000 railway, with a 4'8 1/2" (1435mm) wide gauge. Delays caused by landowners unwilling to gift land for the project, obtaining finance, letting of tenders and the appointment of an engineer lasted throughout 1864. At the end of that year, a contract was offered to Messrs. Higgins and Bloomfield of Melbourne, but they subsequently withdrew.

With the military conquest of the Waikato now effectively over, the Commission focused on constructing an initial line between Auckland and Onehunga, the main port for supplying the occupying military forces and future settlers in the Waikato. It was decided to let the work in small sections with the first, from Mechanics Bay to Newmarket, being granted to Peter Grace on 11 February 1865, with completion planned in sixteen months. Work on this section was to include construction of an embankment in Mechanics Bay, a long cutting across the base of the hill to Parnell and a 265m tunnel under the Auckland Domain beyond. It was considered to be the most important of the sections to complete, and the most difficult to carry out. Grace's initial tender was for nearly £20,000, although the eventual contract appears to have been worth £21,574, a very considerable sum.

Commencement of construction was welcomed for the jobs it afforded the large number of unemployed in Auckland who "clung to the town" during 1864 and 1865, being unwilling to strike out as settlers until the future of the Waikato was decided. By letting out the work in sections the Commissioners expected to save up to £5,000 on the first two legs of the project. The Daily Southern Cross cautioned, however, that the Railway Commissioners did not have the guarantee that a well-established and experienced railway construction contractor could have provided. As Grace appears to have previously been a scoria contractor, the complexity and scale of the work is likely to have exceeded anything he had previously undertaken.

The first sod was turned at a ceremony at Mr Dilworth's field opposite the Junction Hotel, Newmarket on 16 February 1865. Work on Grace's section began immediately, and the digging of the Domain tunnel was going well until rain set in turning the whole area into an unmanageable sea of mud. Plans were revised. It was decided that a viaduct should be built in Mechanics Bay rather than an embankment in order to avoid rendering waterfront land less valuable by preventing access to the foreshore. There is a possibility that this decision was made in response to complaints from local businessmen whose industries were concentrated in the Mechanics Bay area.

Construction of the Mechanics Bay Bridge and Viaduct

From the earliest period of Auckland's colonial history, Mechanics Bay was a major commercial and industrial suburb. Known as Waipapa by Maori, the locality was renamed Mechanics Bay at the foundation of Auckland in 1840, when it was the designated area for occupation by workmen and artisans. Huts, or whare, made of raupo were erected to provide temporary accommodation for the first influx of Pakeha settlers, while in September 1841, suburban sections of land were on the market. Subsequently, substantial industrial enterprises developed, including the sawpits of Messrs Carson and Clark, James Robertson's ropeworks - which produced rope of all kinds for export to Australia - and the business of Henry Nicol and William Sharpe, shipwrights, which remained on the foreshore until 1872. The main thoroughfare between Auckland and Parnell ran along the foreshore, crossing the tidal inlet at the eastern end of the bay via a small timber bridge.

Industrial activity co-existed with Waipapa's function as the main landing reserve for Maori who were importing and exporting goods to the colonial capital by waka, particularly after Tamaki had been sold. In 1848, 20,000 tons of potatoes, apples, peaches and wheat passed through the reserve. Two years later, Ngati Whatua built the Waipapa hostel to house Maori visitors to the town. The reserve upon which the hostel stood was the only piece of Ngati Whatua land in Auckland.

The railway line in Mechanics Bay was surveyed for construction between the Swan Inn on the Parnell Road and Henry Nichol's shipyard. Plans for a bridge and viaduct were in existence by May 1865, produced by James Stewart and Samuel Harding, who had by now been appointed engineers to the Auckland and Drury Railway Board. Stewart appears to have had the main responsibility for the Mechanics Bay to Newmarket section, possibly including the design of the associated works. Changes to the bridge design before its construction included raising its height by 1.3m (4 feet) and widening its arches for foot traffic by 0.6m (2 feet). The design evidently involved a triple-span bridge with scoria piers and a bowstring truss, with further scoria piers forming a viaduct immediately to the south. The structure was erected early in the railway project to allow spoil from the Domain tunnel to be used for an embankment across Mechanics Bay towards the proposed terminus in central Auckland. The proposed embankment would have considerably affected waka transport to Waipapa, and can be seen as reflecting Pakeha attitudes towards Maori at the time of the Waikato War. It can also be perceived as heralding the domination of new transport networks, with less reliance on Maori modes of transportation.

The viaduct piers were due to be laid out in August 1865 but were delayed because Fraser and Tinne, a local engineering concern, failed to remove a large set of rollers from the site. The site of the works may have previously been taken up by sawpits, while a door sill of the adjacent Swan Inn was to be used as the bench mark for the levels. Parts of the piers were built by January 1866, when they were inspected by a Commission of Enquiry, and evidently consisted of ashlar with rubble backing. The Commissioners found fault with the piers, believing the mortar to be of inferior quality, although Stewart responded that the mortar was of slow-drying type and that the masonry 'would bear comparison with any in the Province of its class.' Later engineers noted that the foundations of the piers nearest the foreshore had not been built on top of solid rock.

The Commissioners of Enquiry had been appointed to investigate progress on the line as considerable delays and additional costs had accrued. The overruns on the Mechanics Bay to Newmarket section alone totalled £9,000 by the beginning of 1866. Having taken over the direct running of the project, the Auckland Provincial Council put a stop to as much of the work as possible, although in May 1866 the Provincial Superintendent specifically authorised completion of the bridge and viaduct. Auckland was experiencing a severe economic slump after the removal of the colonial capital to Wellington in 1865, and cutbacks were required. In October 1866, Thomas Cheeseman, Chairman of the Railway Commissioners, reported that the Mechanics Bay bridge and viaduct constructed by Grace were in a 'very forward state' and would be finished the following month. With work on the embankment across Mechanics Bay towards central Auckland not having been started, the structure stood stranded on the foreshore, "a railway to nowhere" until work resumed on the railway line in late 1871 or early 1872.

Julius Vogel and the Waikato Railway

In 1870 the Colonial Treasurer, Julius Vogel (1835-1899), announced a policy of public works that would open up the whole country for settlement with a network of railways. Under the Railways Act 1872, lines were authorised in some fourteen centres, many of which were the forerunners of trunk lines completed later. One of these was the Waikato Railway from Auckland to Mercer, at the new national gauge of 3'6". Work on part of this line, between Auckland and Onehunga, began in the summer of 1871-1872, at which time the Auckland and Drury works were in a state of disrepair. Portions of the line between the Mechanics Bay bridge and the Domain tunnel were buried in clay, with much of the woodwork decayed. Equipment had also been sold to the Bay of Islands Coal Mining Company at Kawakawa, which operated the earliest functioning steam railway in the North Island from 1870.

It appears that by January 1872, rails had been laid down along the Mechanics Bay section to run ballast wagons so that trucks of material could be shot over the end of the bridge, allowing the creation of the embankment that had initially been planned in the 1860s. This occurred as part of an ambitious 7.5 hectare reclamation scheme undertaken between 1872 and 1877, which also involved the quarrying of Fort Britomart Hill, between Mechanics Bay and central Auckland. Modifications to the bridge and viaduct appear to have been carried out, probably during 1872-1873. From photographic evidence, these included raising the outward-facing parts of the bridge piers to create a more imposing-looking structure. The identity of the designer and contractors for the modifications are unknown, although by 1870 James Stewart was employed by the General Government to resurvey the Auckland to Drury line, and by 1874 was in charge of all railway works in the Auckland Province.

The Auckland to Onehunga line - 13km long - opened for use on 24 December 1873, with the Auckland terminus being a simple timber structure near the present intersection of Anzac Avenue and Beach Road. The Auckland to Onehunga line was the first of the 'Vogel Railways' and the first section of railway line to be operated by the General Government. This line, connecting the Waitamata and Manukau Harbours on the east and west coasts, facilitated the linkage of local and international trade operating from Auckland. By May 1875 the line had opened for traffic as far as Mercer, and by 1880 extended south to Te Awamutu. In February 1882 instructions were given for full surveys to determine the best route for connecting Marton with the northern railhead, in anticipation of an uninterrupted trunk line between Auckland and Wellington.

Later alterations

By the 1890s growth in rail traffic increased demand for heavier locomotives and greater bridge strength. In 1896 some timber girders of the viaduct were renewed with iron plate girders imported from the United Kingdom. The remaining kauri beams were renewed in iron bark, while some of the piers were also raised.

By 1907 the main trunk line between Auckland and Wellington was nearing completion, and construction work began on widening the Mechanics Bay bridge and viaduct to accommodate double tracks on this section of the line. Planning for the alterations was already underway in September 1899 when John Coom, the Chief Railways Engineer in Wellington, requested that the District Engineer supply all information required for the design of a new superstructure with 10m spans. This was to replace the pre-existing bowstring bridge, while reusing the existing basalt piers and abutments. Coom's signature, dated 3 August 1907, appears on the first of twelve sheets of plans prepared for the modification of the viaduct and bridge, suggesting that he at least approved the plans if not designed them himself.

Alterations included the replacement of the bow truss by a 39m double-intersection Warren truss. The two secondary-sized piers supporting the bridge over Parnell Rise were consequently removed, enabling the road to be broadened to its current width. The viaduct, now comprising riveted plate girders, carried the track on to the southern abutment. The masonry piers were doubled in width and increased in height to accommodate the new structure. The stone for the new portions of the piers was quarried locally at the Newmarket quarry, and the tops of the piers were finished with concrete. Notwithstanding the increased cost, additions to the wing walls of the abutments were completed to a curved design in keeping with the original stonework. Coom rejected the suggestion of the District Engineer that straight wing walls should be constructed. This construction work was carried out by Railways Department staff.

The eastern side of the structure was ready to take rail traffic on 14 April 1909, with the bridge being fully complete by the end of the financial year (31 March 1910). This coincided with the completion of the Auckland to Wellington Trunk Line in 1909, which was ready in time for crews of a visiting American Fleet to travel the North Island. Completion of the Main Trunk has been considered the most important single event in the history of railways in New Zealand, bringing tremendous improvements in communication, social growth and increased prosperity as a result of the economic boom linked to export of agricultural produce. The North Island line had taken 23 years to build at a capital cost of over £2.5m, more than twice the original estimate.

The bridge at Mechanics Bay formed part of the Main Trunk line until the opening of the 14 km Orakei-Westfield deviation in 1930. Thereafter only commuter trains and rolling stock on the North Auckland line climbed Parnell Bank's steep grade to the Remuera/Newmarket Junction. Minor alterations since then have included the replacement of rails in the 1930s and 1940s, and repairs on the structure in 1945. By 1974, overhead ties were added to the truss.41 Recent work on the Grafton Motorway extension project has resulted in the removal of much of the earlier embankment immediately to the north of the bridge, which has been replaced a new rail bridge. The bridge and viaduct at Mechanics Bay continue in use, and form part of the regional rail network.

Physical Description

Context

The bridge and viaduct lie to the east of the Auckland city centre, at the foot of Parnell Rise. Located in a traditionally industrial suburb adjacent to the Ports of Auckland, the structure marks an important threshold between city, suburb, port and heartland. It retains aspects of its earlier context, with the former Swan (now the Strand) Hotel still located immediately to its west. The main road between central Auckland and Parnell also continues to run beneath the bridge at the northern end of the structure. The viaduct spans an asphalted parking area, terminating at the abutment on the eastern side of Carlaw Park Avenue.

Immediately to the north of the bridge, the recent Grafton Gully motorway to port link has cut through part of the railway embankment, resulting in its replacement by a concrete bridge. To the south of the viaduct, the railway is carried on an embankment and cutting through to the Parnell Tunnel under the Auckland Domain, and then towards Newmarket.

Construction

The structure is orientated approximately north-south. Its base comprises of six stone piers and two stone abutments, supporting a metal superstructure. Most of the piers are rectangular in plan, although two larger ones - at the southern end of each of the bridge and viaduct elements respectively - are approximately triangular. The abutments have a similarly angled groundplan to the larger piers.

The piers and abutments are made up of coursed basalt blocks, slightly rusticated in appearance, either bonded or repointed with a cement mortar. Early references note that the 1860s structure contained rubble backing and was bonded with a mortar incorporating soft sand. Some of the piers retain a projecting string course, which is evident just above the seventh course of masonry. The tops of each pier also contain plain projecting cornices.

The western section of each pier and abutment is considered to incorporate 1860s masonry, although this is not easily distinguished from the later stonework. The new portion of the piers was built independently of the old and connected after the mortar joints had settled sufficiently to prevent any risk of cracks. Visual inspection and archival sources suggest that the stonework from the 1860s and 1870s coincides with the first seven or so visible courses in the western half of the piers. In at least one place there is evidence that stone employed as part of the earlier work has been re-used towards the top of the eastern section of a pier in 1907-1909. A plan, compiled in 1950, clearly shows the extent of the footprint of the earlier stonework found on the western side of the piers and abutments. Additions to the wing walls of the abutments are curved, in keeping with the original stonework.

The bridge section is a 39m, double-intersection Warren truss with overhead ties. Apart from the southernmost girder (which is 10.6m long) the plate girders of the viaduct are 10m long and just over 1m deep. The truss and girders are of riveted construction. The materials and methods of construction used in the superstructure of the bridge and viaduct are of a type commonly employed for railway structures prior to the turn of the twentieth century. The Warren truss, developed by British engineer Captain James Warren in association with Theobold Monzani, has diagonal members to carry both compression and tension forces. As in the USA, where the truss was used until the early twentieth century (mainly in iron and later in steel), the Warren truss was favoured for railway bridges in New Zealand.

The proposed registration also includes a 10m length of embankment immediately to the north of the bridge. This is steep-sided, and forms a remnant of the railway embankment constructed across Mechanics Bay in the 1870s.

Comparisons

Comparatively few surviving bridges in New Zealand date to the 1860s in their entirety, or contain elements from this period. Most of these remnants are road bridges, with one of the earliest being a stone bridge possibly dating from the 1860s over a small tributary of the Clutha River, 16 km south of Balclutha. Its central stone pier has rounded ends, and its stone abutments have curved wing walls like those at Mechanics Bay.

Other early bridges include the Thames Street Bridge, over the Oamaru Creek, Oamaru, part of which dates from 1861 and which is the oldest stone traffic bridge in New Zealand (NZHPT # 2305, Category I); the Helmore's Lane Bridge, Christchurch, a timber structure crossing the Avon River that dates from the mid 1860s (NZHPT #1798, Category II); and the stone and iron Victoria Street Bridge, also in Christchurch, the earliest parts of which were constructed in 1864 (#1832, Category II). The 1860s stone arch bridge spanning the south branch of the Waianakarua River in North Otago (NZHPT #2436, Category II) now has a reinforced concrete deck cantilevered over the sides of the piers and arches.

One of the oldest extant railway bridges in New Zealand is the Ladle Bend Bridge on the Rimutaka Hill line, which is now used by Rimutaka Forest Park vehicles and as part of a public walkway. This was constructed in 1876 on the southern approach to the Rimutaka Incline. It has masonry abutments with a single pier, also masonry. Unlike the Mechanics Bay structure, its superstructure remains as originally designed. The earliest registered railway bridge appears to be one constructed in 1878 at Balclutha (NZHPT #5207, Category II).

Parallels for the double-intersection Warren truss superstructure of the Mechanics Bay bridge are less unusual. Other rail structures in New Zealand that use trusses of this design include the Waiteti viaduct on the North Island Main Trunk, 8km south of Te Kuiti (NZHPT #4175, Category I); the Wingatui viaduct at Taioma on the Taieri Gorge railway line (both of these were completed in 1887); the bridge on the Buller River near Lyell and the Christmas Creek viaduct in the Taieri Gorge (both date from 1890); and the Little Mount Allan viaduct and the bridge over the Sutton Stream where it intersects with the Taieri River (both structures constructed c1890 on the Taieri Gorge line). Like the Mechanics Bay structure, the Lyell Bridge and the Christmas Creek viaduct also feature masonry piers or abutments.

Early bridges featuring basalt as a construction material appear to be unusual. In Auckland, other public works using this material included Mt Eden Prison (NZHPT #88, Category I), which similarly sought to convey a sense of permanence and solidity. Basalt structures in Auckland are frequently early colonial in date, such as the 1859 Melanesian Mission House in Mission Bay (NZHPT # 111, Category I), the Kinder House in Parnell, dating to 1857 (NZHPT #110, Category I), and the c.1861 Bluestone Store (NZHPT #2647, Category I).

Construction Dates

Designed
1865 -

Original Construction
1865 - 1866

Modification
1872 - 1873
Outer face of stone piers carrying superstructure over Parnell Rise raised in height.

Modification
1895 - 1896
Bridge and viaduct superstructure partly renewed in iron. Some, masonry piers raised in height.

Modification
1907 - 1909
Bowstring bridge superstructure replaced by Warren truss, and viaduct superstructure also replaced. Two masonry piers removed from Parnell Rise roadway and others widened to accommodate the support of a double-track railway

Other
1945 -
Repairs

Addition
1957 - 1971
Overhead ties added to truss

Construction Details

Basalt piers, capped with concrete. Wrought iron bridge truss, with steel-plate viaduct superstructure.

Completion Date

21st October 2004

Information Sources

Archives New Zealand (Auck)

Archives New Zealand (Auckland)

Bridge No.1, Main Trunk Line Parnell 1893-1906, BANM 14406 A714 520b 496 pt 1; Bridge No.1, Main Trunk Line Parnell 1906-1909, BANM A714 520c 496 pt 2; Bridge Number 1, Main Trunk Line, Parnell 1929-1956, BANM A714 520d 496 pt 3; Parnell - Bridge Contract 1906, BABJ 14406 A681/F393 1359; New Zealand Rail Limited - Railnet Auckland, BABJ 14406 A681/F39 25588; Minutes of Meetings of Railway Commissioners, AP11/2.

Daily Southern Cross

Daily Southern Cross

17 February 1865, p.4

Furkert, 1953

Frederick William Furkert, Early New Zealand Engineers, Wellington, 1953

Journals of the Auckland Provincial Council

Journals of the Auckland Provincial Council

Session XVIII 1864-1865 & Session XIX 1865-1866

Leitch, 1972

David B. Leitch, Railways of New Zealand, Auckland, 1972

Lowe, 1974

David Lowe, Tracks Across the Isthmus, Henderson, [1974]

Simmons, 1987

David Simmons, Maori Auckland, including Maori Place Names of Auckland. Collected by George Graham, Auckland, 1987

Thornton, 2001

Geoffrey Thornton, Bridging the Gap, Early Bridges in New Zealand 1830-1939, Auckland, 2001

Weekly News

Weekly News

Christmas and New Year's Supplement, 25 December 1880, p.6

Other Information

A fully referenced version of this report is available from the NZHPT Northern Region Office

Please note that entry on the New Zealand Heritage List/Rarangi Korero identifies only the heritage values of the property concerned, and should not be construed as advice on the state of the property, or as a comment of its soundness or safety, including in regard to earthquake risk, safety in the event of fire, or insanitary conditions.