New Zealand DM class electric multiple unit
| New Zealand DM/D class | |
|---|---|
 D2778 awaiting departure from Johnsonville, the terminus of the Johnsonville Line, 17 December 2007. | |
| In service | 2 July 1938 – 25 June 2012 |
| Manufacturer | English Electric |
| Built at | Preston Works, United Kingdom |
| Constructed | 1938-1954 |
| Entered service |
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| Refurbished | 2005–2007 (Tranz Metro) |
| Scrapped |
|
| Number built | 49 |
| Number scrapped | 41 |
| Formation |
|
| Fleet numbers |
|
| Capacity |
|
| Operator | Tranz Metro |
| Lines served |
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| Specifications | |
| Car length | 19.2 metres (63 ft 0 in) |
| Width | 2.61 metres (8 ft 7 in) |
| Doors | 4 |
| Maximum speed | 97 km/h (60 mph) |
| Weight | 43.5 t (42.8 long tons; 48.0 short tons) |
| Power output | 447 kW (599 hp) |
| Electric systems | 1,500 V DC overhead |
| Braking systems | Air, handbrakes |
| Track gauge | 1,067 mm (3 ft 6 in) |
The New Zealand DM/D class electric multiple unit[a] (also known as English Electrics) are a type of electric multiple units used on the suburban rail network of Wellington, New Zealand. Formed of DM power cars and D trailer cars, the first units were ordered from English Electric in 1936 and introduced on 2 July 1938 operating the electrified Johnsonville Line service. Additional units were ordered in 1942 for the line, and in 1946 as the other Wellington suburban lines were to be electrified.
The units were relegated to peak services and the Johnsonville Line after the arrival of the "Ganz-Mavag" EM/ET units in 1982–1983, before finally being replaced by the "Matangi" FP/FT units in 2011–2012. The units operated their last revenue service on 25 June 2012, from Wellington to Melling and return. Five complete units (four two-car and one three-car) and six trailer cars have been preserved.
Introduction
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Following its decision to build the Tawa Flat deviation to replace the original Wellington and Manawatu Railway Company portion of the North Island Main Trunk (NIMT) alignment out of Wellington, the New Zealand Railways Department (NZR) decided to convert the remaining 10.49 kilometres (6.52 mi) of track between Wellington and Johnsonville into an electrified suburban branch line. Six two-car trains comprising one driving motor car and one driving trailer were ordered from English Electric in 1936 to work the future Johnsonville Line, which formally opened as a branch line on 2 July 1938 with the new electric trains inaugurating the service. The new trains were allocated as the DM class (driving motor cars) and the D class (non-motored driving trailer).[1][2] The first order became known as the "36 stock" by the year it was ordered (1936).[3]
The first sets were shipped to New Zealand in January 1938.[4] They arrived on SS Cambridge in February and were landed by the floating crane, Hikitia.[5]
Due to traffic growth both on the Johnsonville Branch and with further electrification in the Wellington suburban area, two further orders were placed with English Electric for further trains of this type; three motor cars and two trailers were ordered in 1942 and delivered in 1946 following the end of the Second World War, while forty motor cars and seventy-one trailers were ordered in 1946 and delivered from 1949 onwards to work the Paekākāriki and later Upper Hutt and Melling services. Due to the limited number of these trains, NZR was required to run additional locomotive-hauled carriage trains until the arrival of the first Ganz Mavag EM/ET units in 1982.[6]
Operation
[edit]The class operated in two principal configurations:
- Two-car unit (DM-D). Used on the steep Johnsonville Line until March 2012, as four-car trains for peak and two-car trains off-peak and weekend; 38.4 metres long with a tare weight of 69.7 t (68.6 long tons; 76.8 short tons), full seated load 79.9 t (78.6 long tons; 88.1 short tons). Two car units were also operated on the Melling line. Until March 2012 there were 11 two-car units in service.
- Three-car unit (D-DM-D). Used on the Wellington to Taita line (extended to Upper Hutt from 1955), and the Wellington to Paekākāriki line; as six carriage sets during peak periods and three carriage sets off-peak and weekends; 57.5 metres (188 ft 8 in) long with a tare weight of 99.5 t (97.9 long tons; 109.7 short tons).
Up to 1983 when electrification was extended to Paraparaumu some (D-DM-D) units were hauled from Paekākāriki by diesel locomotives, usually the DA class. They were fitted with extra storage batteries for lights and other electrics.
Renumbering
[edit]The introduction of the Traffic Monitoring System (TMS) in 1979 saw the units renumbered.
Replacement
[edit]By the late 1970s, planning began to replace the '36 and '42 stock due to their increasing unreliability.[7] In an editorial published in the New Zealand Herald the Minister of Railways Colin McLachlan stated that the government intended to purchase new suburban rolling stock.[7] In addition to mechanical issues, the units heaters and doors were often faulty, leading to passenger discomfort.[8] A tender to replace the units and all carriage-hauled suburban trains in Wellington, was announced on 6 March 1978.[9]
Technical details
[edit]As originally built, the DM class motor cars seated 56 passengers and D class trailer cars seated 72. During the renovation of these trains in the late 1970s and early 1980s, two seats located next to the driver's cabs in each car were removed and a barrier was installed level with the cab, reducing the seating in each car to 54 passengers per DM car and 70 passengers per D car. Some DM cars had the double seats in the rear section in front of the luggage compartment removed and the seats parallel with the sides extended to provide space for prams.[10]
As originally built, the DM class motor cars had a second driver's cab located in the luggage compartment at one end of the car allowing them to operate as single car units. The second cabs were progressively removed to provide spare parts giving increased luggage space. Prior to this, the all-night service on the Johnsonville Branch was operated by one of the 1942 stock DM cars, an arrangement which was considered for use on a similar service on the Melling Branch.[10]
Each car had ten 150 V electric heaters in series run off the 1500 V supply, so a 1500 V connection was required between motor cars and trailers.[10] 46 stock differed from 36/42 stock in some respects:
- 36/42 stock motor cars had a 120 V DC motor-generator set supplying power for lights, signal circuits and brake & door operation; 46 stock set were fitted with a higher-capacity motor-generator set to supply two trailers rather than one.[10]
- The bogie wheelbase on 36/42 stock was 7 ft 6 in (2.29 m); 46 stock were four feet longer at 8 ft 0 in (2.44 m).[10]
- The 36/42 stock had taller windows, delivered without ventilation louvres in the doors; 46 stock had shorter windows and were delivered with ventilation louvres in the doors.[3]
- The 36/42 stock had one coach-mounted brake cylinder only; 46 stock had Westinghouse electro-pneumatic air brakes and automatic brake equipment.[11][10]
Because of their shorter wheelbase and the smaller motor-generator set designed for one trailer only, 36/42 stock units were kept for the Johnsonville line as much as possible.[10] Similarly, the three-car sets of 1946 stock were kept for use on the Paekākāriki, Melling and Upper Hutt services due to their greater passenger-carrying capacity and reduced brake capacity on steep lines.
Refurbishment
[edit]The introduction of the EM/ET "Ganz-Mavag" class units from 1982 onwards saw a large number of the class become redundant, namely all of the '36 and '42 stock.[12] Ten two-car units of '46 stock were refurbished at the now closed East Town Railway Workshops in Wanganui between 1984 and 1986,[13] for continued operation on the Johnsonville Branch, where EMs did not have running rights due to their being over-gauge and having insufficient braking capacity, and for peak-hour running on the Hutt Valley and Melling lines.
In the early 2000s, the remaining members of the class underwent a moderate refurbishment to extend their operational lives to 2012. The refurbishment largely involved a cosmetic upgrade of the exterior and interior of the cars, with new seating and a major mechanical overhaul. As part of this the cars received the new two-tone Tranz Metro blue livery with the exception of DM556 and its trailer cars D 2130 and D 2411 which were repainted into the old Midland Red livery with silver roof and black running gear in 2006. Trailer unit D 2660 was sent to Hillside Workshops for an overhaul in 2002.
In February 2007, overcrowding on Wellington trains resulted in the recommendation by the Greater Wellington Regional Council to re-introduce two DM/D units, one former Tranz Metro unit stored at Hutt Workshops as a source of spare parts and another from the Ferrymead Railway. These units entered service from October 2008.[14] With no further DM/D sets available, the two overhauled sets were joined as a short-term measure by six ex-British Rail carriages rebuilt at Hillside Workshops as the SE class and worked in push-pull service by two Toshiba EO class locomotives.[15]
Withdrawal
[edit]First withdrawals
[edit]Due to the arrival of the Ganz-Mavag electric multiple units in the early 1980s withdrawals of the D/DM class began in November 1981 with the scrapping of set DM55 and trailer D2007 (DM 1 and D 101).[16] Further withdrawals of earlier sets occurred until July 1983 when the last two sets of 1942 stock were withdrawn for scrapping, while the 1936 stock had all been withdrawn and scrapped by April of that year. Only one of the 1946 sets had been withdrawn - motor coach DM 13 had been withdrawn and scrapped in April 1978 after being involved in an accident.
At the time of their withdrawal, the D/DM sets were among the oldest rolling stock operated by KiwiRail. By this time all remaining D/DM class sets were composed of 1946 stock, the '36 and '42 stock having been withdrawn from service in the early 1980s.
Final withdrawal
[edit]Following the arrival of the new FP/FT Matangi units into service from January 2011 onwards, Metlink began to progressively withdraw the DM/D sets from regular service, starting with the Hutt Valley services. All but three of the three-car D/DM/D sets were withdrawn with the exceptions of DM 251, DM 504, and DM 556 "Cyclops". These sets continued in regular service until DM 556 was reduced to a two-car set for Johnsonville Branch use in December 2011; both DM 251 and DM 504 continued relatively trouble free in service until 27 March 2012, when both were withdrawn from service after the evening peak services that day.
Due to the nature of operations on the Johnsonville Branch and the need to increase the nominal catenary voltage for full Matangi operation, operation of the Johnsonville Branch needed to be cut over immediately rather than phased in as elsewhere on the network. This caused issues due to delays in the introduction of further Matangi units and the voltage increase which led to a number of electrical failures on the older DM/D sets. As the sets deteriorated in condition they were withdrawn from service, allowing cars with little or no problems to be combined in place of failed cars in order to maintain service.
By October 2011, former Hutt Valley sets DM 27 "Robin", DM 216 "Phoenix" and the now shortened DM 556 were pressed into service due to a lack of available Johnsonville DM/D sets. Following the failure of DM 216 in December, DM 556 was pressed into service with one trailer removed and coupled to the uphill end of DM 27 due to the loss of the second driving cab in DM 556. Three further sets comprising DM 182, DM 441 and DM 510 were later repaired to maintain service with buses supplementing trains at peak times.[17]