Maharashtra approves Mumbai Metro Line 12A, a ₹13,856-crore corridor linking Kalyan-Dombivli with Navi Mumbai, with a 3.5-year completion target. The Maharashtra Cabinet Infrastructure Committee on Tuesday approved the 18.40-km-long Mumbai Metro Line 12A, which is expected to improve connectivity between Kalyan -Dombivli in Thane district and Navi Mumbai.