Indian locomotive class WDM-3D

The Indian locomotive class WDM-3D is a diesel-electric locomotive that Banaras Locomotive Works at Varanasi developed in 2003, together with the Research Design and Standards Organisation, for Indian Railways. The name stands for broad gauge, diesel and mixed traffic engine, with 3D marking its 3,300 horsepower rating, although the name would suggest 3,400. It is the higher powered sibling of the WDM-3A, built around an enhanced 16-cylinder Alco 251C engine with improved fabricated high-adhesion bogies and a stated maximum speed of 160 km/h. The first unit was built in July 2003 and serial production began in late 2005; the article gives the run as more than 490 units to 2016 in its lead and over 590 in its history section. Nine went to Sri Lanka Railways in 2012 as the M10 class, and Bangladesh received gifted units from 2020. As of September 2026, 369 remained in mainline service.