began in the 1960s and 1970s. The network was initially protected from road transport competition under the Transport Licensing Act 1931, but this protection was gradually eased until its total abolition in 1983, along with the deregulation of the land transport industry. The networks of the North and South Islands were independent of one another until the introduction of the inter-island roll-on roll-off rail ferry service in 1962 by the Railways Department, now branded The Interislander. Corporatised ownership (1982–1993) In 1982, the Railways Department was corporatised into a new entity at the same time land transport was deregulated. The Railways Department became the New Zealand Railways Corporation. The Corporation embarked on a major restructuring, laying off thousands of staff and cutting unprofitable services. After the 1983 land transport deregulation, there was a substantial rationalisation of freight facilities; many stations and smaller yards were closed and freight train services were sped up, increased in length and made heavier, with the removal of guard's vans in 1987 and the gradual elimination of older rolling stock, particularly four-wheeled wagons. In 1987, the Railways Corporation became a state-owned enterprise, required to make a profit. In 1990, the core rail operations of the Corporation were transferred to New Zealand Rail Limited, another state-owned enterprise, with the Corporation retaining non-core assets which were gradually disposed of, including a significant land portfolio. In many cases, the Corporation did not dispose of land due to Treaty of Waitangi claims and has continued to manage land. Private ownership (1993–2004) New Zealand Rail Limited was privatised in 1993. The company was sold for $328.3 million to a consortium named Pylorus Investments Limited. In 1995 the new owners adopted the name Tranz Rail and listed the company on the New Zealand stock market and NASDAQ. Rail freight volumes increased between 1993 and 2000 from 8.5m net tonnes to 14.99m net tonnes carried annually, and then gradually fell until 2003 to 13.7m tonnes. Freight volumes then increased again to 16.1m tonnes carried annually in 2012. Tranz Rail was accused of deliberately running down some lines through lack of maintenance. The Midland Line for example, which mostly carries coal from the West Coast to Lyttelton, was assessed to be in a safe but poor state by the LTSA government safety body in 2003, and has needed major repairs. Tranz Rail was accused of forcing freight onto the roads, and in 2002 introduced a