The Indian locomotive class WDM-3D is a class of diesel–electric locomotive that was developed in 2003 by Banaras Locomotive Works (BLW), Varanasi for Indian Railways. The model name stands for broad gauge (W), Diesel (D), Mixed traffic (M) engine with 3300 horsepower (3D). The engine is classified WDM-3D though it outputs only 3300 hp and not 3400 hp as the name should suggest. They entered service in 2003. A total of 590+ WDM-3D were built at Banaras Locomotive Works (BLW), Varanasi between 2003 and 2016.
The WDM-3D is one of the most successful locomotives of Indian Railways serving both passenger and freight trains. A few WDM-3D units were exported or gifted to neighboring countries like Sri Lanka and Bangladesh. A significant number of these locomotives are still in use, both on mainline and departmental duties. As of October 2021, most of the locomotives still retain "operational status" on the mainline as WDM-3D, with further examples having been converted from WDM-3B.
