WAP - 4 is a common electric locomotive used in India. The locomotive was developed after a previous class WAP-1 was found inadequate to haul the longer, heavier express trains (24-26 coaches) that were becoming the mainstay of the Indian Railways network. It was introduced in 1994, with a similar bodyshell to the WAP-1 class, but with Hitachi traction motors developing 5,350 hp (3,990 kW) (5,000 hp or 3,700 kW Continuous. The locomotive can be seen in service across the electrified network of Indian Railways and is homed at 14 sheds (depots).