The foundation stone of the project was laid by Indira Gandhi, the Prime Minister of India, on 29 December 1972, and construction work started in 1973–74. Initially, cut and cover along with slurry wall construction to handle soft ground, was recommended by the Soviet Union Consultants. Later, in 1977, it was decided to adopt both shield tunneling and cut and cover methods for construction under populated areas, sewer lines, water mains, electrical cables, telephone cables, tram lines, canals etc. The technology was provided by M/s NIKEX Hungarian Co., Budapest. In the early days, the project was led by the Union Railway Minister from West Bengal, A. B. A. Ghani Khan Choudhury, often against the prevailing socio-political stance of his contemporaries in the West Bengal government. From the start of construction, the project had to contend with several problems including insufficient funds (until 1977–1978), a shifting of underground utilities, court injunctions, and an irregular supply of vital materials. In 1977, an injunction for the allocation of new funding was passed by the newly elected Jyoti Basu government.