On the Hokuriku main line, a steep tunnel of the same name made it necessary to develop a powerful AC electric locomotive. Its tasks included the haulage of 1,300 tonne freight trains on a one percent incline or of passenger trains with 100 km/h. The solution was the EF70 that had three two-axle bogies and of which 81 were built between 1961 an 1965. In 1968, seven were modified for use on sleeper trains. By 1985, most locomotives had been removed from active service. The official retirement of the last one was in March 1987. 