Passenger services Not long after the completion of the
Wellington–Manawatu Line by the
Wellington and Manawatu Railway Company (WMR) on 3 November 1886, the
New Plymouth Express was introduced, jointly operated by the WMR and NZR. Upon its introduction in December, its timetable was the subject of protests. The service stopped at only the larger towns, prompting indignation from residents of smaller towns who felt that the line's wayside traffic was being sacrificed so that through passengers could save an hour's travel time. Local traffic was primarily catered for by slow
mixed trains. The Express initially operated twice weekly, with connections to
Onehunga in
Auckland by steamer. In 1901 the express began operating daily; in 1908, with the incorporation of the WMR into the NZR, the service was run by a single government operator; and from 1909, the steamer connections ceased as direct expresses between Wellington and Auckland began operating on the newly opened NIMT. In 1926, the
Taranaki Flyer passenger train was introduced between Wanganui and New Plymouth, replacing one mixed train. Two additional mixed trains ran south from New Plymouth daily. The opening of the
SOL in 1933 saw the introduction of the
New Plymouth Night Express between Auckland and New Plymouth, using the MNPL between New Plymouth and Stratford. It ran thrice weekly, with extra trains at peak periods. In 1938, the
RM class Standard railcars entered service and they operated an evening service between Wellington and New Plymouth to complement the Express. In a test run, one of these railcars completed the journey in 6.5 hours. Difficulties on the 1 in 35 grades of the original Turakina route and Westmere Bank meant that the railcars had to have different gears installed, reducing their top speed from 120 km/h to 105 km/h. Increasing competition from road and air services led to a decline in passengers after World War II. The New Plymouth Express and Taranaki Flyer ran for the last time on 31 October 1955 and were replaced by Standard and
88-seater railcars. The New Plymouth Night Express was similarly replaced by 88-seater railcars the next year. The railcar substitute for the Taranaki Flyer ran for the last time on 7 February 1959, but the other services survived into the 1970s. From 1968, the sole services operated by the Standard railcars were those on the MNPL and SOL; they were finally displaced from these services in late 1972. The 88-seaters were ageing and plagued by reliability problems, and on 30 July 1977 all passenger trains between Wellington and New Plymouth were cancelled, thus ending passenger service between Marton and Stratford. The railcars replacing the New Plymouth Night Express had ceased to operate the Auckland-
Taumarunui section since 1971, and when they were withdrawn after 11 February 1978, a
diesel-hauled carriage train was introduced on the New Plymouth to Stratford and Taumarunui run. It ran for the last time on 21 January 1983 and was the last regular passenger train to operate on any part of the MNPL. Since this time, the only passenger services have been excursions.
Freight In the early years of the line, freight was primarily local and the railway served as a link between ports and their hinterland. Long-distance freight progressively developed over the course of the 20th century, aided by the decline of coastal shipping and the need to carry freight to ports in other regions. Freight services using the full length of the line fell as low as a single service each weekday, with services to and from the north routed via the SOL and then the NIMT. Three daily services transported products along the Hāwera–New Plymouth section from the
Fonterra factory at Whareroa until Fonterra elected to shift its container traffic to the Ports of Auckland and Tauranga. Nowadays the line sees two-weekday freight services between Palmerston North (departing 2350 and 0355) and New Plymouth (departing 1530 and 1815) and up to three daily return services between Palmerston North and Whareroa, carrying milk from the Manawatu and Hawkes Bay (via a facility at Oringi and rail from there) to the Fonterra plant and empty milk tankers and containerised products on the return trip through most of the year. Other services include regular services along the
Kapuni Branch for urea, and with the opening of an inland port facility in Wanganui in 2010 by Open Dairy a daily service exists to/from Palmerston North via the
Wanganui Branch and the reopened
Castlecliff Branch.
Passing loops are at Ruatangata (near
Turakina),
Whanganui,
Kai Iwi,
Waitotara and
Pātea. The mothballing of the SOL in 2010 now means all northbound freight must transition through Marton.
Motive power Steam locomotives were the primary motive power on the MNPL until the early 1960s.
Tank locomotives were prevalent until the 1920s. At the start of the 20th century,
WB class locomotives were based in Wanganui,
WA and
WF locomotives from Palmerston North were used on the line, and
M and
double Fairlie E class locomotives were based in New Plymouth.
Tender locomotives only gained precedence in the 1920s with the introduction of the
AB class, though WF locomotives continued to assist over the difficult grades out of Aramoho.
WW class tanks were also used on the MNPL in this era. After World War II,
K and
KA locomotives were introduced, the most powerful steam power used on the line. and from the mid-1950s a variety of railcars were introduced for the passenger services. In the early 1960s
DA class diesel locomotives began taking over most freight duties, with steam locomotive workings ceasing in 1966. When introduced in 1972, the
DX class were not common on the MNPL largely owing to the need to strengthen bridges to accommodate their weight. As the DA class were phased out in the 1980s, DX class locomotives became frequently used on the line. During the 1990s and early 2000s, the dominant locomotive classes at the time (
DC,
DFT, DX) operated on the line, usually in multiple and with a DX class unit usually present on all services due to the power advantage they have when climbing the Westmere Bank. The peak season milk trains, for instance, were usually hauled by a pair of DX units owing to the weight of these services. The
DL class locomotives have been used on MNPL services following their introduction to the lower North Island in 2011. With the withdrawal of the DC class and the relocation of the DX and relevant subclasses to the South Island, the DL class is the dominant locomotive class on the MNPL. Motive power on the line regularly consists of pairs of DLs or DFs or mixed with other motive power subject to availability. ==Former stations==