During the 1950s, demand began to significantly decline as competition from aeroplanes and the private car increased. Business travellers increasingly opted for other options, although the schedule was steadily improved to 13.5 hours each way. In the North Island all "Limiteds" went from steam to diesel power in 1963, and the afternoon expresses in 1964. The change, according to the railway annual report for 1965, "has eliminated smoke nuisance in tunnels and has enabled the journey time to be reduced by approximately 50 minutes". Diesel-electric motive power was typically provided by members of the DA class.