Commuting in the city of Mumbai is set to change. Work on the 33-km Colaba-Bandra-Seepz Line 3 is in full swing. The overall tunnel length for the corridor is 53 km. Phase 1 is to be completed by December 2021. The project will reduce travel time by half. Line 3 would take 4.5 lakh vehicles off the roads. Take a closer look at Mumbai's first underground Metro. BTVI Correspondent Karishma Asoodani is 80 feet below the ground to witness the buzzing construction activity.