New Zealand DA class locomotive

The New Zealand DA class locomotive were a class of diesel electric mainline locomotives operated on the New Zealand railway system between 1955 and 1989. Consisting of 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 (EMD) G12 model, with the design altered slightly to run on New Zealand's 3ft6in rail system, and fit the small loading gauge. They were introduced between 1955 and 1967 in three phases and were the first class of diesel locomotives to seriously displace steam traction. Between 1978 and 1983, 85 locomotives were rebuilt as the DC class, of which some 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 All but one of the remainder were withdrawn by 1989, with six preserved.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 and was rebuilt as DAR 517.

The DA class have their origins in the post World War II period. Like most nations New Zealand's dominant form of railway traction was steam, with electrification being used in Wellington, the Christchurch Lyttleton Line and through the Otira Tunnel. The General Manager of the New Zealand Railways (NZR), 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 or diesel traction would be required on other lines. Aickin went as far as negotiating a supply contract in 1946, 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 locomotives and facing significant capacity issues on the NIMT, NZR entered into an agreement with General Motors for the supply of 30 G12 model locomotives following a tender process. Designated by NZR as the DA class one of the major appeals was the guarantee of delivery within five months. They were the first locomotives supplied from the United States of America since the AA class of 1914. With two production lines at London, Ontario and La Grange, Illinois two locomotives were completed every three days. At the time, they were the highest and widest locomotives ever used in New Zealand.

This first batch of 30 locomotives were built by EMD, with 15 built at their Canadian subsidiary General Motors Diesel in London, Ontario, and 15 built at their La Grange, Illinois plant. Known as Phase I, (DA 1400–1429) entered service between August 1955 and January 1956.

A second batch of ten locomotives (DA 1430–1439) were built by Clyde Engineering in Sydney and entered service during 1957. The Australian built locomotives, which became known as Phase II, differed from the Phase I locomotives in having a shunter's refuge at the No. 2 end, and were 1’ 6’’ (0.46 m) longer between bogie centres, with slight additional weight. The locomotives featured cast steel bogies manufactured by Dofasco in Canada. The phase I locomotives were delivered with fabricated bogies, these were later replaced with Dofasco bogies as well. The order was approved by Cabinet on 26 June 1956 on Clyde Engineering for ten DA class locomotives, to cost £NZ674,560. This followed a visit to Clyde in Sydney on 13 June 1956 by the Minister of Railways John McAlpine and the NZR General Manager Alan Gandell. The price was assessed as 6.6% above the Canadian price, but reference was made to the reciprocal trade agreement with Australia. Phil Holloway (Labour) asked a question in Parliament on 22 August 1956 about the extra cost.

Three further batches were ordered, all supplied by General Motors Diesel, London, Ontario. The first 12 units (DA 1440–1451) were dubbed as Phase III and entered service in 1961. The Phase III locomotives were the same length as Phase I, but with different headlight arrangement. The 106 Phase III units entering service from 1961 to 1964 (52) and 1966–67 (54), taking the total number in the DA class to 146. Only Phase III units were selected for rebuilding into the DC class locomotives from 1978 onwards. This final order saw the end of steam traction in the North Island. At the same time the final DA order was made, an order for smaller and lighter DB class locomotives was also placed with EMD. 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 DA class locomotives, it weighed 97.5 tonnes compared to the combined weight of two DA class at 162 tonnes, which combined with more powered axles gave better traction and higher power to weight ratio. The Silver Star service was later transferred to the DX class, 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 DA class on the NIMT. Units were also employed on the Auckland suburban network, hauling 56 foot carriages. The 40 locomotives that were not converted to the DC class continued in service throughout most of the 1980s. The combination of the deregulation of land transport and the 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 North Auckland Line through the Makarau Tunnel which prevented DC locomotives working in Northland, twelve DA class locomotives were given an "A grade" overhaul in 1980 with some modifications to improve crew comfort. They were painted in International Orange 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 1979 the computerised Traffic Monitoring 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 class number. Under the numbering DA 1400 became DA11 and DA 1516 became DA996, prior to it being rebuilt into DC4830.

From their introduction, the class were painted in an overall deep red colour described 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 locomotives redesignated as DAA received gold stripes to differentiate them from other DA and DB class locomotives. Following the introduction of TMS many had their new road numbers applied to the long hood. During the 1980s some locomotives 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. Many units were retired still wearing the original NZR 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. The locomotives were reclassified as the DAA class. They received additional low speed controls to assist in these operations, special in cab Signals to indicate "faster", "slower", "maintain power" and "stop" for drivers linked back to the grid control tower by VHF radio, and a separate VHF radio channel for voice communication to the control tower. These locomotives were identifiable by their yellow hood stripes, which were treated 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. DAA 1400 (formerly DA 1400) was written off in November 1983 due to generator damage, being replaced by DA68, DA28 was out of service from February 1986 and the remaining four locomotives were withdrawn in February 1988. Over seven years, 80 were rebuilt by Clyde Engineering in Adelaide, while a further five were rebuilt at Hutt Workshops using a mixture of components built at Hutt and Clyde. The first few were shipped directly to Port Adelaide, but after the Union Company withdrew its roll on/roll off services, most were shipped to Melbourne's Appleton Dock and hauled to Adelaide via the 1600 Victorian and South Australian lines. 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 a rivalry between locomotive 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 speeding on a curve, and nearly ended up on State Highway 1 below the line; both of the crew were killed. Ten of the Phase III locomotives were not rebuilt. Many of the DC class remain in service today with ownership held by KiwiRail. Several were leased to Auckland Transport. One, DC4588, 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 & 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. NZR initially offered a DH class locomotive as a replacement. Tasman did not feel the locomotive would be up to the task. At the time, NZR was withdrawing the last DA class locomotives, and the decision was made to offer DA512 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 painted in Tasman's orange brown colours before it entered service at Kawerau. This allowed the Bagnall to be withdrawn, and later scrapped after 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. DA512 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 DAR517, the locomotive was released from Hutt in 1999 and allocated to the Kiwi Dairies milk factory at Whareroa, near Hāwera. Here, it replaced ex NZR Bagnall DSA414 (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 September 2008 for an overhaul and was placed in storage at Hutt Workshops. The locomotive was scrapped in December 2017.

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. By 19 December 1987 18 DA class locomotives were still in service, with the majority (12) being in service for use on the North Auckland Line. By April 1989 only one DA class locomotive, DA512, remained. Following their withdrawal, most units were taken to Hutt for scrapping during the early 1990s, though a few were scrapped elsewhere.