The proposed Rs 2,619-crore 16.75 km metro expansion project in Kolkata has cleared a big hurdle with the defence ministry granting primary approval for the project.
 
 Specifically, the ministry allowed Indian Railways to go underground on the Maidan stretch of the Joka-BBD Bag Metro route. 
 
 Railways secured the primary approvalafter a series of meeting at ministry level over the last one year. The project, envisaged in 2010, hit a roadblock as Defence ministry opposed construction in its territory citing security and environment-related reasons. 
 
 Nearly 8 km of the journey through the defence land will be underground. The rail ministry has been in discussion with the Defence Ministry to get permission to begin the commissioning process on that stretch.
 
 The route map for the project was finalised in January 2010, which was followed by the announcement of the expansion plan in the 2010-11 railway budget presented by then Railway Minister Mamata Banerjee.