On a weekday evening last month, Mumbai's southbound Aqua Line metro train nearly emptied out a couple of stops before the final one. On de-boarding, the last station bore the look of a desolate Soviet-era structure rather than a bustling train terminal in a city where crowds typically jostle for space. Aqua Line is the city's new fully underground metro train connecting the old business district of Cuffe Parade to newer commercial hubs like BKC and the airport terminals in the northern suburbs.