New Zealand DA class locomotive

New Zealand DA class locomotive

Company type	Diesel-electric locomotive
Industry	Rail transport
Founded	1955
Founder	New Zealand Railways (NZR)
Defunct	1989 (retirement of most units)
Headquarters	New Zealand
Area served	New Zealand North Island rail network
Products	Diesel-electric locomotives
Parent	New Zealand Railways (NZR)

The New Zealand DA class locomotive represents a diesel-electric mainline engine that operated across New Zealand's rail system from 1955 until 1989. With a total production of 146 units, it stands as the most numerous locomotive class in the country, surpassing even the steam-powered NZR AB class in quantity.

Derived from the Electro-Motive Diesel G12 model, the DA class was specifically modified to accommodate New Zealand's track gauge and limited loading clearance. Introduced in three stages between 1955 and 1967, these locomotives played a crucial role in phasing out steam-powered engines.

From 1978 to 1983, 85 of these locomotives underwent rebuilding into the New Zealand DC class locomotive, with some still active today. The majority of the remaining units were retired by 1989, while six have been preserved for heritage purposes. Additionally, one locomotive was converted for shunting duties and designated as DAR 517.

Introduction

The D^A class emerged during the post-World War II period when New Zealand Railways (NZR) aimed to transition from steam to diesel-electric power. General Manager Frank Aickin initially promoted electrifying the entire North Island Main Trunk (NIMT) line to minimize reliance on coal and reduce diesel fuel imports. However, after his departure in 1951, government plans for electrification were abandoned. Following operational difficulties and capacity limitations encountered with the D^F class, NZR commissioned General Motors to supply 30 G12 locomotives, designated as the D^A class, notable for their guaranteed delivery within five months. These were the first American-built locomotives delivered to NZR since 1914 and were manufactured swiftly at two North American facilities. At their introduction, they represented the largest locomotives ever operated in New Zealand.

Phase I

The first group of 30 D^A locomotives (numbers 1400–1429), classified as Phase I, was produced by EMD—half constructed at General Motors Diesel in London, Ontario and half at La Grange, Illinois—and entered service between August 1955 and January 1956.

Phase II

The second series comprised ten units (D^A numbers 1430–1439), built by Clyde Engineering in Sydney during 1957 and referred to as Phase II. These featured design enhancements such as a shunter’s refuge at the No. 2 end and were extended by 1 foot 6 inches between bogies with a slight increase in weight. Both initial phases utilized cast-steel bogies supplied by Canadian firm Dofasco, replacing the fabricated bogies originally fitted on Phase I locomotives.

On 26 June 1956, the New Zealand government approved a £NZ674,560 contract for Clyde Engineering’s ten locomotives following a ministerial inspection in Sydney. Despite costing approximately 6.6% more than their Canadian counterparts, this pricing was justified under reciprocal trade agreements with Australia, even though it attracted parliamentary scrutiny over the price differential.

Phase III

Three further orders were placed with General Motors Diesel in London, Ontario. The first of these additional batches consisted of twelve units (D^A numbers 1440–1451), designated Phase III, which commenced service in 1961. These units matched Phase I in length but incorporated a revised headlight configuration.

Overall, 106 Phase III locomotives were introduced between 1961–64 (52 units) and 1966–67 (54 units), culminating in a total DA class fleet of 146 units. Only Phase III models were selected for conversion into DC class locomotives starting in 1978. This final procurement effectively marked the conclusion of steam locomotive use on the North Island.

Concurrently, an order was placed with EMD for smaller and lighter D^B class locomotives intended for operation on secondary lines with lighter track infrastructure unsuitable for the heavier D^A class engines.

In service

The D^A class locomotives were predominantly utilized across the North Island. To accelerate their deployment, a larger loading gauge was accepted, initially restricting their operation to the North Island Main Trunk (NIMT) between Auckland and Paekakariki, as well as certain branch lines such as Rotorua and Kinleith. Due to weight limitations, these locomotives were barred from many branch routes and had limited presence on the East Coast Main Trunk beyond Paeroa, where lighter classes like the D^F and D^B were preferred. These constraints were gradually lifted following bridge strengthening projects and the inauguration of the Kaimai Tunnel in 1978.

Early models featured an axle load of 14.8 tonnes and were equipped with fabricated bogies, confining them to freight duties. Subsequent units, starting with D^A 1440, incorporated Dofasco cast steel bogies alongside enhanced spring systems, allowing them to perform express passenger services.

Initially, tunnel clearances south of Paekakariki prevented D^A locomotives from reaching Wellington via the NIMT; this section was serviced by electric locomotives. However, after the tunnel floors were lowered in 1967, D^A units gained full access to operate along the entire NIMT route to Wellington.

The D^A class was deployed across all principal North Island lines, including the NIMT, Marton–New Plymouth, Palmerston North–Gisborne, and North Auckland routes. Their dependable performance contributed to phasing out steam engines by 1967 and enhanced freight capacity on the NIMT—for instance, hauling loads of up to 650 tonnes over the Raurimu Spiral compared to 595 tonnes managed by their K^A steam predecessors.

These locomotives managed a variety of freight and passenger services such as the Scenic Daylight on the NIMT. The Silver Star overnight sleeper train initially operated with pairs of D^A units (numbers 1520–1527, later joined by 1528).

To meet the demand for more powerful traction on the NIMT, NZR introduced fifteen D^X class locomotives in 1972. While a single D^X produced slightly less power than two combined D^As, its reduced weight and improved adhesion resulted in superior overall performance.

Eventually, the Silver Star shifted to using D^X locomotives, while the Scenic Daylight service was replaced by Blue Streak railcars. Additional D^X units delivered during 1975–76 ended the dominance of the D^A class on the NIMT. Some D^As also operated suburban Auckland services hauling 56-foot passenger carriages.

Throughout most of the 1980s, forty unmodified D^A locomotives remained active. However, declining rail freight volumes, deregulation in land transport sectors, reduced passenger patronage, and electrification of the NIMT rendered many units redundant. Due to clearance restrictions within Northland’s Makarau Tunnel preventing DC class use, twelve D^As underwent "A grade" overhauls in 1980 that included enhancements for crew comfort and a repaint into International Orange livery.

Numbering

The numbering scheme for NZR diesel locomotives was established with the introduction of the D^A class, assigning sequential numbers beginning near the rated horsepower figure of each unit. Although these engines were rated at 1425 hp, numbering commenced at 1400 and extended up to 1545.

With the launch of the computerised Traffic Monitoring System (TMS) in 1979, remaining units were renumbered sequentially under capitalized class designations. During the DC rebuild programme, some locomotives received temporary DA series numbers prior to conversion and subsequently new DC class identifiers. For example, D^A 1400 became DA11 before conversion and was later redesignated DC4830; similarly, D^A 1516 was renumbered DA996 before its rebuild.

Livery

Originally, the class sported a solid deep red color known as New Zealand Government Railways red, accented with white or silver stripes running along the sides and culminating in wing-shaped designs.

To differentiate the D^AA locomotives from the D^A and D^B classes, gold striping was applied. Following the introduction of the Traffic Monitoring System (TMS), updated road numbers were placed on the long hood.

During the 1980s, a number of units were repainted in the International Orange scheme—characterized by red side panels, grey on both upper and lower surfaces, and yellow safety ends—featuring large white road numbers on the long hood. Many locomotives remained in their original NZR red livery upon retirement.

D^AA class

In 1970, mainline service for locomotives D^A 1400 through 1404 and 1406 ended as they were reassigned to heavy shunting duties at the newly established Te Rapa hump yard. These units were reclassified as D^AA class and upgraded with low-speed controls, specialized in-cab signaling linked via VHF radio to the yard control tower, alongside a dedicated VHF channel for voice communication.

Yellow stripes on the hood identified these locomotives’ specialized shunting function.

Eventually superseded by purpose-built DSG and DSJ shunters, D^AA 1400 was retired in November 1983 due to generator failure; DA28 ceased operation in February 1986; the last four units were withdrawn by February 1988.

Two examples of the D^AA class have been preserved. After withdrawal in 1983, D^AA 1400 underwent cosmetic restoration to its original D^A 1400 appearance and was donated to Auckland's Museum of Transport & Technology (MOTAT), notable as the first locomotive built in the D^A series.

D^AA 1401 (TMS DA28) was retired in 1986 and scrapped before being acquired by enthusiast Tony Bachelor in 1988 for his Pacific Rail Trust. It was leased to Tranz Rail in 1999 but saw limited use, subsequently stored until reactivated in 2005. Loaned to the Feilding and District Steam Rail Society in 2007, it was gifted to them in 2008 for restoration work. Although nominally operational, it requires repairs before returning to mainline service.

DC class

Starting in 1977, NZR undertook a program to rebuild thirty Phase III GM Canada-built D^A class locomotives into EMD G22AR models, resulting in the creation of the D^C class. Over a seven-year period, Clyde Engineering at Adelaide refurbished eighty units, while an additional five were rebuilt at Hutt Workshops using parts sourced from both facilities. Initially transported via Port Adelaide, most later arrived through Melbourne’s Appleton Dock, moving over Victorian and South Australian rail networks due to discontinuation of roll-on/roll-off shipping services.

Among the final fifty-four Phase III D^A locomotives, only one—D^A 1517—was not rebuilt, having been scrapped after an accident in 1974. Despite suffering severe accident damage involving fatal derailments caused by excessive speed, two others—D^As 1533 and 1470—were rebuilt. Ten Phase III units never underwent rebuilding.

Numerous DC class locomotives remain active within KiwiRail’s fleet, with several leased to Auckland Transport. One unit, DC 4588, was exported to Tasmania in 1999 but withdrawn from service in 2002 due to motor problems. Following an incomplete rebuild attempt, it was ultimately scrapped by TasRail in 2011.

DAR class

In 1989, Tasman Pulp & Paper aimed to replace its Kawerau-based shunting locomotive, the Bagnall 0-6-0DM No. 3079, which, despite an engine upgrade in the late 1970s, was no longer capable of managing the increased workload.

Initially, NZR proposed a DH class as a replacement, but Tasman deemed it unsuitable. With the DA class locomotives being phased out by NZR, DA512 was offered as a heavy-duty shunter substitute. After modifications including removal of the front dynamic brake hood and enhancements to cab visibility, it received Tasman’s orange-brown paint scheme and commenced operations at Kawerau. This allowed the retirement and scrapping of the Bagnall unit.

In 1998, Tasman sold DA512 back to Tranz Rail, which upgraded it at Hutt Workshops by adding shunter's refuges and lengthening the drawgear for more demanding shunting tasks. Renumbered as DAR 517 and repainted in "Cato Blue," it was deployed at Kiwi Dairies’ Whareroa milk processing plant near Hāwera, taking over from Bagnall DSA 414. In 2005, DAR 517 received Toll Rail’s "Corn Cob" livery before being withdrawn for refurbishment in 2008 and eventually scrapped in December 2017.

Withdrawal

Throughout the 1980s, the DA class fleet was progressively reduced due to diminishing operational requirements and the deteriorating condition of units that had not undergone rebuilding. The majority of first-series locomotives were retired by late 1986. By December 1987, only eighteen DA units remained active, with twelve primarily operating on the North Auckland Line.

In March 1988, Railways Corporation introduced single-person train operation; however, the DA and DJ classes were considered unsuitable owing to their cab designs. By April 1989, just one DA locomotive (DA512) continued in service. Most withdrawn locomotives were dismantled at Hutt Workshops during the early 1990s, with a small number scrapped at other locations.

Preservation

A total of six DA class locomotives have been preserved:

• DA 1400/DAA 1400 (TMS DA11): As the class leader, it was donated to Auckland’s Museum of Transport & Technology (MOTAT) in 1983. Following static restoration, it was relocated indoors to MOTAT’s Meola Road facility in 2014 to ensure preservation.
• DA 1401/DAA 1401 (TMS DA28): Initially sold for scrap in 1986 but acquired by Tony Bachelor in 1988 for the Pacific Rail Trust. Briefly leased to Tranz Rail in 1997 with limited use before storage at Hutt Workshops. Reactivated by Toll Rail in 2005 for Feilding and District Steam Rail Society (F&DSR), which received it as a donation in 2008.
• DA 1410 (TMS DA126): Purchased from NZ Rail in 1988 by Steam Incorporated. It underwent overhaul in 1999 and was loaned to Railway Enthusiasts Society at Glenbrook Vintage Railway. Returned to Steam Inc. in 2015 and is certified for heritage passenger operations on the National Rail Network.
• DA 1429 (TMS DA322): Acquired by Tony Bachelor in 1987; leased to Tranz Rail between 1997 and 2003. Sold in 2010 to Auckland enthusiast Dean McQuoid and transferred to Glenbrook Vintage Railway. Its national network registration has expired and it requires significant refurbishment.
• DA 1431 (TMS DA345): Obtained by Steam Incorporated in 1989 and loaned to Railway Enthusiasts Society in 1998. Restored alongside guards' van F345 at Paekākāriki and returned to service in 2009.
• DA 1471 (TMS DA725): Preserved as a heritage locomotive by Palmerston North depot staff in 1988. Leased to Steam Incorporated in 2002, recalled by Toll Rail in 2007, then purchased outright by Steam Inc. for preservation in 2012; currently undergoing restoration.

At present, only DA1410 and DA1431 hold registration for operation on the National Rail Network, with plans underway to register DA1471 and DA1401 in due course.