They were initially hauled by members of the first J class steam locomotives and limited to a speed of 60 km/h (37 mph), resulting in a journey time of eleven hours.
The restrictions were removed by the late 1940s when the express, at its zenith, reached sustained higher speeds on the Canterbury Plains and became the South Island Limited from 1 August 1949.
[4] From 1956, the consolidation of the daylight schedule into one express each way increased to 21 stops, but only 20 minutes were added to the overall running table, with departure from Christchurch at 8.40 am and arrival at Invercargill at 8.20 pm.
By this time, officials generally conceded that much faster running than the 100 km/h (62 mph) authorised was often required to meet the tight timetable,[5] on a single-track railway over the Canterbury and Southland plains.
The northbound South Island Limited, train 144 to connect with the Inter-Island Ferry, left Invercargill at 7.40 am to arrive at Christchurch at 7.20 pm for a 17-minute break, before 144 moved on to Lyttelton with adequate time to connect with the inter-island ferry leaving Lyttelton at 20.30, required the performance of the JA class hauled expresses if 20 minutes or later out of Timaru with the 100 miles to Christchurch and 5 scheduled stops, largely to pick up mail at Temuka, Orari, Ashburton, Rakaia and Burnham.
Am optional sixth stop at Rolleston for northbound 144 on Fridays was timetabled in 1967-1970, due to politicians pressure to provide a connection with an evening railcar to Arhurs Pass and Greymoutn with recovery speeds, sometimes exceeding 120 km/h (75 mph).
[8][better source needed] The original consist of the South Island Limited was three first and four second-class carriages providing 330 seats overall[9] with a capacity of over 500 in the school holidays.
[9] The main traffic for the South Island Limited was as a long-distance service to connect with the inter-island Union Steamship Company Steamer Express ferry at Lyttelton and to carry mail, with up to six ZP class wagons for maximum revenue.