Singh, a civil engineer, worked with Sreedharan on the Kolkata metro project and has been associated with Delhi metro since its inception. He is in charge of Delhi metro's Phase-III expansion programme which will add another 103km to the existing 189.6km network. Singh is also responsible for DMRC's consultancy activities for planning metro projects in Ahmedabad, Chennai, Hyderabad, Kochi, Kolkata and Mumbai.

The first section of metro opened in Delhi on December 24 2002 between Shahdara and Tis Hazari. Currently the network comprises six lines plus the Airport Express Line, which Singh oversaw the construction of.