Until its nationalization in 1956, the physical limitations of the Canal had greatly influenced world shipowners with regard to the sizes of ships built, particularly oil tankers. Following nationalization, in an era of cheap oil and transport costs, shipowners took the initiative and began to build large tankers. Mindful of the effect that such changes would have on the tonnage of oil transported through the Canal, the Suez Canal Authority began a programme of expansion in 1958 which was to be executed in two stages. The first stage was completed by February 1964 and consisted of widening and deepening the Canal so that ships with draughts of 38 ft could be accommodated, thus allowing vessels of 60,000 d.w.t. to transit fully loaded. The second stage of development was intended to deepen the Canal to accept vessels of draughts up to 40 ft, corresponding to ships of 70,000 d.w.t. This work was scheduled to be completed by the end of 1967, but the project was not finished due to the start of the Arab–Israeli war.