The NZR Da Class was one of NZ's early diesels.
The New Zealand DA class diesel-electric mainline locomotives operated on the New Zealand railway system between 1955 and 1989. With 146 locomotives, it was the most numerous class to ever operate in New Zealand, with five more than the AB class steam locomotive.
The class were A1A-A1A versions of the Electro-Motive Diesel G12 model, with the design altered slightly to run on New Zealand's 3 ft 6 in (1,067 mm) rail system, and fit the small loading gauge. They were introduced between 1955 and 1967, and were the first class of diesel locomotives to seriously displace steam traction.
Between 1978 and 1983, 85 were rebuilt as the DC class, of which many are still in use. All but one of the remainder were withdrawn by 1989, with six preserved. The last locomotive was refitted for shunting duties, becoming DAR 517.
The DA class have their origins in the post-World War II period. Like most nations New Zealand’s dominant form of traction was steam, with electrification being used in Wellington, the Christchurch - Lyttleton Line and through the Otira Tunnel. The General Manager of the Railways Department, Frank Aickin, was an advocate for electrifying the entire North Island Main Trunk (NIMT) to alleviate the shortage of coal and the cost of importing diesel fuel; though he also recognised that steam and diesel traction would be required on other lines.
Aickin went as far as negotiating a tentative contract for construction, but fell out with the Government in 1951 and retired. His successor, H.C. Lusty, terminated the contract. After a disappointing experience with the DF class  and facing significant capacity issues on the North Island Main Trunk (NIMT) NZR entered into an agreement with General Motors for the supply of 30 G12 model locomotives following a tender process. Designated by the Railways Department as the DA class one of the major appeals was the guarantee of delivery within five months. With two production lines at London, Ontario and La Grange, Illinois two locomotives were completed every three days.
This first batch (DA 1400-1429) entered service between August 1955 and January 1956. The next batch (DA 1430-1439) were built at Clyde Engineering in Australia and entered service during 1957.
Three further batches were ordered, all supplied by General Motors Canada from their Montreal plant. The first 12 units (DA 1440-1451) were dubbed as 'Phase II' and entered service in 1961, with the 94 'Phase III' units entering service from 1962-64 (40) and 1966-67 (54), taking the total number to 146.
The class operated in the North Island. To facilitate their fast delivery a 'looser' loading gauge was accepted meaning that initially they could only serve on the NIMT from Auckland to Paekakariki, and the Rotorua and Kinleith branches. They were excluded from operating on many branch lines on account of their weight, and were restricted in their operations on the East Coast Main Trunk beyond Paeroa due to the line through the Karangahake and Athenree gorges with NZR using the lighter DF and DB class to handle traffic on this line. These restrictions were reduced as bridges were progressively strengthened, and in the case of the ECMT the opening of the Kaimai Tunnel in 1978.
The class were also unable initially to access Wellington via the NIMT, as the tunnels south of Paekakariki built in the 1880s by the WMR were not large enough for them. The operational practice remained the same as it had in the steam age with an exchange with ED and EW electric locomotives taking place at Paekakariki, until the tunnel floors were lowered in 1967 and they could operate through to Wellington. Access to Wellington before this time could only be achieved via the Wairarapa line and the Rimutaka Tunnel.
Eventually DAs were employed on all the major lines in the North Island – the NIMT, Marton-New Plymouth, Palmerston North-Gisborne and North Auckland lines. The success of the DA in its reliability and performance meant that it was the major factor allowing the withdrawal of North Island steam locomotives by 1967. The class were successful in raising the freight capacity of the NIMT. The main limitation was the Raurimu Spiral, where a pair of DA's could haul 650 tonnes up the grade compared to 595 tonnes for their KA steam predecessors.
The class hauled all manner of freight and passenger services, including the "Scenic Daylight" service on the NIMT. The prestigious "Silver Star" overnight sleeper train was initially hauled by a pair of DA locomotives when it was introduced in 1971. A dedicated pool of locomotives - DAs 1520-1527 and later joined by 1528 - were used for this service.
However the need for a more powerful locomotive that could haul longer and heavier trains on the NIMT had been identified and in 1972 the first 15 DX class locomotives were introduced. While a single DX produced 70 kW less than a pair of DAs, it weighed 97.5 tonnes compared to the combined DAs 162 tonnes, which combined with more powered axles gave better traction and higher power to weight.
The Silver Star service was later transferred to the DXs, while the Scenic Daylight service had earlier been replaced by the "Blue Streak" railcars. The introduction of further DX class locomotives in 1975-76 ended the dominance of the DAs on the NIMT.
Units were also employed on the Auckland suburban network, hauling 56-foot carriages. These services terminated at the Auckland Railway Station, forerunning the services run by many of the DC class today.
Those locomotives that were not converted to the DC class continued in service throughout most of the 1980s. However the combination of the deregulation of land transport and decline in rail freight volumes, reduced inter-regional passenger numbers, and the electrification of the NIMT saw them become surplus to requirements. Due to tunnel clearance problems on the Makarau Tunnel which prevented DC locomotives working in Northland twelve DAs were given an 'A Grade' overhaul in 1980 with some modifications to improve crew comfort. They were painted in 'fruit salad' colours at the same time.
The DA class established the initial numbering practice for NZR diesel locomotives, numbering the units sequentially with the class leader numbered in reference to the locomotives horsepower. While the locomotives were actually rated at 1425 hp, numbering started at 1400, and continued up to 1545.
In 1980 the computerised Traffic Management System (TMS) was introduced, with the remaining members of the class renumbered in sequence and the classification capitalised. Because this took place during the DC rebuild programme some units received a new 'DA' series number before being withdrawn for conversion, upon which they received a new 'DC' number. Under the numbering DA 1400 became DA 11 and DA 1516 became DA 996, prior to it being rebuilt into DC 4830.
From introduction the class were painted in an overall deep red colour christened as New Zealand Government Railways red. White or silver stripes were added along much of the length of the body, culminating in 'wings' on each end. The units redesignated as DAA received gold stripes to differentiate them from other DAs and the DB units. Following the introduction of TMS many had their new road numbers applied to the long hood.
During the 1980s some units were repainted in the 'International Orange' livery (red sides, grey upper and lower surfaces and yellow safety ends) then being applied to other NZR locomotives, with the road number applied in large white type on the long hood. However, many units were retired still wearing the original NZGR red.
In 1970, locomotives DA 1400-04 and 1406 were withdrawn from mainline duties and reassigned as heavy shunters to work in the new Te Rapa hump yard. They received additional low speed controls to assist in these operations and were reclassified as the DAA class. These locomotives were identifiable by their yellow hood stripes, which were treated so to denote them as being used in special service apart from the DA class. The locomotives were later superseded by the DSG and DSJ class shunting locomotives, which were purpose-built for shunting as opposed to the DAA class being converted for that purpose, and were withdrawn progressively in the 1980s.
Two DAA class locomotives have been preserved. On its withdrawal in 1983, DAA 1400 (TMS DA 11) was cosmetically restored as DA 1400 and donated to the Museum of Transport and Technology in Auckland. Placed on static display at MOTAT's Great North Road site, it was moved in late 2014 to MOTAT's Meola Road site to make way for an upgraded pavilion surrounding steam locomotive K 900. It is significant as the first of the DA class to have been built.
The other, DAA 1401 (TMS DA 28) was withdrawn in 1986 and forwarded to Sims-PMI scrap yard at Otahuhu. In 1988, the locomotive was purchased by enthusiast Tony Bachelor, who moved it around various homes in the Auckland area as part of his Pacific Rail Trust. In 1999 it was leased to Tranz Rail, but received little use and was stored at Hutt Workshops. In 2005, the locomotive was re-activated, and in 2007 was loaned to Feilding District Steam & Rail at the conclusion of the lease agreement with Tranz Rail and Toll Rail. DA 1401 was gifted to the FDS&R in 2008, who are now planning for its eventual restoration.
Between 1977 and 1983, NZR decided to rebuild many of the later 'Phase III' GM Canada-built DA class locomotives into the EMD G22AR model to become the DC class. During the seven-year rebuilding period, 80 locomotives were shipped to Adelaide and railed to Clyde Engineering in Australia for rebuilding, while a further five locomotives were rebuilt at Hutt Workshops using a mixture of componentry built at Hutt and Clyde.
Only one of the final batch of 54 'Phase III' DA class locomotives was not rebuilt - DA 1517 had been scrapped in 1974 due to damage sustained when it ran into a landslip at the entrance to the Fordell tunnel in 1973. Two locomotives - DAs 1533 and 1470 were both rebuilt from heavily damaged conditions sustained in accidents running light engine. 1533 was damaged in an accident while returning from National Park on banking duty in 1975; due to rivalry between loco drivers at Taumarunui depot, the locomotive entered a curve too fast and overturned, killing the locomotive engineer. 1470 derailed on the steep Pukerua Bay section in 1978 returning to Wellington due to overspeeding on a curve, and nearly ended up on State Highway 1 below the line; both crew were killed.
Ten of the initial 'Phase III' batch were also not rebuilt. Two of the 'Phase II' locomotives - DAs 1441 & 1446 - were amongst those rebuilt.
Many of the DC class remain in service today with ownership held by KiwiRail, and several leased to Auckland Transport. One, DC 4588, was exported to Tasmania in 1999, but found to be unsuccessful and was withdrawn in October 2002 with serious motor problems. After a long period of inactivity, the locomotive, which had been partway through a rebuild to make it more suitable for Tasmanian conditions, was sold for scrap by TasRail in mid-2011.[
In 1989, Tasman Pulp and Paper was looking to replace their resident Kawerau shunting locomotive, Bagnall 0-6-0DM NO 3079. This locomotive had been rebuilt in the late 1970s with a new Caterpillar D343T diesel engine and torque converter to make it more effective as a heavy shunter, but due to increases in traffic, was no longer able to keep up.
New Zealand Rail initially offered a DH class locomotive as a replacement, however, Tasman did not feel the locomotive would be up to the task. At the time, NZ Rail was withdrawing the last DA class locomotives, and the decision was made to offer DA 512 as a new heavy shunter.
The locomotive was altered by 'chopping' the front hood containing the dynamic brake components and altering the cab for better forward visibility. It was then renumbered as DA 822 and was painted in Tasman's orange-brown colours before it entered service at Kawerau. This allowed the Bagnall to be withdrawn, and later scrapped after briefly being offered to the Bay of Islands Vintage Railway.
In 1998, Tasman decided to sell its locomotive back to Tranz Rail, who would then take over the duties of shunting the Kawerau yard with more conventional shunting locomotives. As a result, DA 512 was sold to Tranz Rail, who immediately moved it to Hutt Workshops for further alterations to make it more suitable as a heavy shunting locomotive. This included fitting shunter's refuges at either end of the locomotive, and extended drawgear to accommodate the extra length of the refuges, as well as a repaint in the then-current 'Cato Blue' livery.
Renumbered as DAR 517, the locomotive was released from Hutt in 1999 and allocated after much speculation to the Kiwi Dairies milk factory at Whareroa, near Hawera. Here, it replaced ex-NZR Bagnall DSA 414 (DSA 240, the sub-class leader) as the resident shunting locomotive. It was repainted in the Toll Rail 'Corn Cob' colours in 2005, but was withdrawn from service in 2009 and placed in storage at Hutt Workshops. Currently, there are no plans for its return to service.
With the lack of ongoing operational requirements and the age of the units that were not rebuilt themselves the number of units was reduced throughout the 1980s. Most of the first batch delivered were withdrawn by the end of 1986. Following withdrawal most units were taken to Hutt for scrapping during the early 1990s, though a few were scrapped elsewhere.
Da1400 at MOTAT 2 Auckland
Da1401 at Feilding and District Steam Rail Society
Da1410 at Steam Incorporated Paekakariki
Da1429 at Glenbrook Vintage Railway
Da1431 at Steam Incorporated Paekakariki
Da1448 is now DAR 512 / At Hutt Workshops
Da1471 at Steam Incorporated Paekakariki
Only two of the locomotives, DAs 1429 and 1431 are currently mainline certified although there are plans for DA 1401 to be so.