Railway signalling in New Zealand

[6] Other manufacturers used were Siemens, AEI-GRS, GPT Plessey, GRS Syncrostep, and British Power Railway Signalling Co (B.P.R.S.)

[7] Power-operated points were generally electrically driven with 110V ac Westinghouse Brake and Signal (WBS), M2, M3 and M5 style equipment.

At Auckland, Dunedin and the Te Rapa marshalling yard were air operated (pneumatic).

They were marked with the serial number and the names of the station at each end of the section; and had a range of notches and types of centre hole to match them to pairs of machines.

Later (safer) mechanical exchangers were used, although some stock (DX locomotives and Silver Fern railcars) did not have tablet forks, and slings had to be used unless the train stopped there.

Some places had a weekly "jigger" trip to return a tablet; e.g. Mangaroa (between Upper Hutt and Kaitoke) and Canterbury (Rakaia to Bankside).

[13][14] Each tablet-station required three (tablet) porters and a station-master, often at isolated locations in the country, with each having a NZR staff house.

The sections were:[2] Centralized traffic control (CTC) was installed on 2 October 1938 between Okahukura and Taumarunui (10.8 km), then in December 1939 between Te Kuiti to Puketutu (13.9 km); so enabling new intermediate crossing loops at Taringamotu and Waiteti.

[17] The 1925 Fay-Raven Commission recommended the full introduction of the "Train Control" system throughout New Zealand, .

In 1957 it was announced that the remaining outdated sections (354 km) would be converted to CTC; with control centres at Ohakune, Taihape and Palmerston North.

It was estimated that this would save 74 staff on traffic duties required for the Taumarunui to Otaki section.

The rural settlements of the King Country have been depopulated, and few trains now stop at Kune, which had been the operations centre for the Taumarunui-Waioru section.

[19] Light railcars (Midland and Wairarapa classes) were a problem on both the Midland and Wairarapa lines, as after non-use of the line e.g. overnight the wheel-to-rail resistance was too high to detect them by "shunting" the track relays until a loco had been over the track; this also happened from heavy sanding by locos and with the heavier Standard (Aotea) class railcars on the Palmerston North - Gisborne Line.

[20] In June 2022 signalling equipment failures at Auckland and Wellington disrupted life for many commuters on busy suburban lines for several days.

It was eventually traced to a loose card remote from the signal box which was installed ten years ago; the manufacturer could not identify the error code.