principles, i.e. signals tell the driver what speed they should proceed, but not necessarily the route they will take. The Auckland suburban network is also equipped with European Train Control System (ETCS) Level 1 signalling and train protection. Signalboxes and signalling were supplied by McKenzie & Holland from their factory in Melbourne. The largest mechanical box in New Zealand was Frankton Junction, 85 miles south of Auckland, with 70 levers. Motive power Steam From its inception until the 1950s, steam locomotives were the main motive power on New Zealand's railways. Initially, steam locomotives were mostly imported from the United Kingdom from various manufacturers. The first major class was the F class tank locomotives, of which 88 were imported. From the 1870s, locomotives were imported from the United States, and generally found to be better suited to New Zealand's conditions, although the pro-British public and politicians preferred locomotives from the United Kingdom. In 1889, NZR began manufacturing its own locomotives, starting with the NZR W class. Local engineering firm A & G Price also manufactured a significant number of steam locomotives for NZR. Diesel Dieselisation of rail transport began in the late 1940s with small shunting locomotives. The first mainline diesel locomotives, the English Electric DF class, were introduced in 1954, but it was not until the introduction of the DA class locomotives the following year that steam began to be seriously displaced in the North Island. The last steam locomotive to be built by NZR, JA 1274, was introduced into service in December 1956, and by 1967, steam had all but disappeared from the North Island. Steam remained in the South Island until November 1971, when the last seven JA locomotives that worked the Main South Line were withdrawn from revenue service, steam in the South Island having been displaced by the DJ class locomotive. Starting from the mid-1970s, the first generation diesel locomotives were withdrawn, being replaced by new locomotives, predominantly designs from North America. The General Electric manufactured DX class were introduced from 1972 to 1975, and the original DF class were withdrawn and the General Motors DF class introduced from 1979. NZR also rebuilt some of the DG class locomotives. At the same time, the newest locomotives of the DA class were rebuilt as DC class locomotives in Australia and New Zealand. The last of the first-generation diesel locomotives were withdrawn in the late 1980s and early