The New Zealand DA class locomotive is a class of diesel-electric mainline locomotives operated on the New Zealand railway system between 1955 and 1989. Consisting of 146 locomotives, it is the most numerous class to ever operate in New Zealand, with five more locomotives in service than the AB class steam locomotive.
The class is an A1A-A1A version of the Electro-Motive Diesel (EMD) G12 model, with the design altered slightly to run on New Zealand's 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 All but one of the remaining locomotives were withdrawn by 1989, with six preserved. The last locomotive was refitted for shunting duties and was rebuilt as DAR517.
Introduction 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, Horace Lusty, terminated the contract. After a disappointing experience with the DF class locomotives,Alecock, G.J., 'The Development of NIMT Motive Power Part 2' Rails March 1993 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.
Phase I
This first batch of 30 locomotives were built by EMD, with 15 built at their Canadian subsidiary General Motors Diesel in London, Ontario,New Zealand Order New York Times 27 October 1955Off-the-Hook Diesels for NZR Railway Transportation August 1956 pages 33, 42 and 15 built at their La Grange, Illinois plant.
Known as Phase I, (DA 1400–1429) entered service between August 1955 and January 1956.
Phase II A second batch of ten locomotives (DA 1430–1439) were built by Clyde Engineering in Sydney and entered service during 1957."Locomotives that have Crossed the Tasman" Australian Railway Historical Society Bulletin issue 396 October 1970 page 232 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.Archives New Zealand file reference R20480896
Phase III Three further batches were ordered, all supplied by General Motors Diesel, London, Ontario. The first 12 locomotives (DA 1440–1451) were dubbed as Phase III and entered service in August 1961. The Phase III locomotives were the same length as Phase I, but with different headlight arrangement. This order saw the end of steam traction in the North Island. The 52 Phase III locomotives entered service from 1961 to 1964.
Phase IV In 1966, NZR again reviewed its motive power needs and went to tender, again selecting the G12 as the best option. Between 1966 and 1967, 54 DA class locomotives entered service, known as Phase IV. The main difference between the Phase III and Phase IV locomotives was the use of the EMD 567E engine. This order took the total number in the DA class to 146. Only Phase III and Phase IV locomotives were selected for rebuilding into the DC class locomotives from 1978 onwards.
At the same time the final DA class order was made, an order for smaller and lighter DB class locomotives was also placed with EMD. The DB class were used on lightly laid secondary lines where the DA class were unable to be used.
In service The class operated in the North Island. To facilitate their fast delivery a greater loading gauge was accepted meaning that initially they could only operate on the NIMT from Auckland to Paekakariki, and the Rotorua, Kinleith and Tokoroa 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 (ECMT) beyond Paeroa due to the lightly laid line through the Karangahake and Athenree gorges. Instead the lighter DF and DB class locomotives handled traffic on this line. These restrictions were reduced as bridges were progressively strengthened, and in the case of the ECMT with the opening of the Kaimai Tunnel in 1978.
Their axle loading was . The first (1955) locomotives had fabricated bogies welded from steel pressings and because of the roll on curves were restricted to goods service. Later batches (from DA 1440) had Dofasco cast steel bogies with an improved spring layout and were suitable for express working.
The class were also unable initially to reach Wellington via the NIMT, as the tunnels south of Paekākāriki built in the 1880s by the Wellington and Manawatu Railway Company did not have enough clearance under the 1500V DC Wellington suburban electrification overhead wires. The operational practice remained the same as it had in the steam age, with an exchange with ED and EW class electric locomotives taking place at Paekakariki. The tunnel floors were lowered south of Paekakariki in 1967 and the DA class could then operate all the way through to Wellington. Access to Wellington before this time for the DA class could only be achieved via the Wairarapa line and the Rimutaka Tunnel.
The DA class 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 class 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 class locomotives could haul 650 tonnes up the grade compared to 595 tonnes for their KA class 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 class 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.Class Da Diesel-Electric Locomotives New Zealand Railway Observer issue 133 Autumn 1973 page 35
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. Locomotives 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.
Numbering The DA class established the initial numbering practice for NZR diesel locomotives, numbering the locomotives 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 locomotives 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.
Livery 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 locomotives were retired still wearing the original NZR red.
Conversions and rebuilds DAA class
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.