Advertisement for Aqua Line at Bandra-Kurla Complex.
I recently spent several days in Mumbai, where I rode the new Aqua Line (Metro Line 3) several times. The Aqua Line is Mumbai’s first subway line, and, because its route takes it through many of the city’s most important destinations, it’s a particularly important facility. The line was opened in full just a few months ago, in October 2025, and, when I was in Mumbai, the city was plastered with signs like the one shown above: the authorities believe that the Aqua Line is the key to Mumbai’s becoming a modern city.
Some background, as usual, is in order.
Mumbai has in common with many other cities that date from the colonial era—among them, New York, Hong Kong, Boston, and Dakar—a rather awkward geography. The colonizers of these cities wanted a good port that could easily be defended. Thus, in New York and Hong Kong, they chose a small part of a modest island, and, in Boston and Dakar, they chose the end of a long peninsula. The original site of Mumbai was on a small island, but, thanks to extensive landfill, it’s become the end of a peninsula. The locations of all these colonial-era cities became a problem as the cities grew into enormous places. There was a need to move a huge number of people and goods every day to a location surrounded on three sides by water and with only so much room for transportation facilities to the interior.
Mumbai’s solution to the problem was the development of several multi-track suburban railroad lines that ended up at two stations near the end of its peninsula: Churchgate and Chhatrapati Shivaji (formerly Victoria) Terminals. These rail lines have been transporting more than seven million passengers a day. It’s likely that, among the world’s suburban railroads, only Tokyo’s far larger number of lines carries more passengers.1
Mumbai’s suburban lines have been famously overcrowded for decades.2 Because very little of the rolling stock even today is air-conditioned, passengers must often hang onto the sides of the trains’ open doors, and some fall off every day.
Mumbai also has a 20-km-long monorail line, the first segment of which opened in 2014. The line was built at the behest of the company, Scomi Engineering Berhad, that built Kuala Lumpur’s monorail. It runs through industrial and medium-density residential areas in east-central Mumbai that are mostly served poorly by the suburban railway system. The Mumbai Monorail has never had a large ridership, in part because its route is not very useful and in part because it’s rather slow. The line has often been closed because of mechanical difficulties. The construction of the Mumbai Monorail seems to have been an experiment that just didn’t pan out. While there have been plans to add new lines, no one’s moved to implement these for many years.
Passengers getting off a train at the terminus of the Mumbai Monorail. Photograph made in 2014.
Like other Indian cities, Mumbai, thanks in part to national-government support, has started to build a system of more conventional metro lines in recent years, but, because (like Kolkata) it already had an urban rail system, it’s tended to go about the process in a different way than, say, Delhi, which has traditionally had only a modest number of suburban rail lines. Mumbai’s first metro line, the Blue Line (Metro Line 1), which opened in 2014 (after the Monorail), cuts east-west across the suburban rail lines, connecting stations on these lines with a couple of important commercial areas.
Map of part of the Mumbai area emphasizing rail transit lines and pedestrian facilities. The nominal scale of the map is 1:110,000. That’s the scale it would have if printed on a 17-x-11-inch sheet of paper. GIS data are mostly derived from the Geofabrik version of OpenStreetMap. I’ve edited all the data. The map is clickable and downloadable, but note that this site’s host server does not allow images to be stored at their original resolution, and, if you zoom in too far, the image will be blurred.
The Blue Line is entirely elevated. Its stations are huge.
The Airport Road station on the Mumbai Metro’s Bl;ue Line. Note the train up the track. The air quality index was over 300 when I took this photo.
It mostly runs along a busy road that carries massive amounts of traffic.
Andheri-Ghatkopar Link Road, under the Blue Line. The traffic jam-up is more or less typical.
The line runs trains frequently—every three-and-a-half minutes for much of the day—and it carries an enormous number of passengers—something like half a million a day. This is a very high number for a line only 12 km long.
Passengers waiting as a train arrives at the Blue Line’s Airport Road station.
Mumbai’s next metro lines were sections of the Red and Yellow Lines (Line 2 and Line 7). They are being operated for the moment as a single service that follows an upside-down U-shaped itinerary. The line runs through economically heterogeneous northern outer-city neighborhoods that are served to some extent by the Western suburban line, but the routes of the metro lines generally operate much closer to dense housing areas than the Western line. Like the Blue Line, these lines are entirely elevated. Unlike on the Blue Line, the stations have waste-high platform doors that prevent passengers from falling onto the tracks. An elaborate elevated corridor allows transfer to the Blue Line.
Blue Line train from a bridge connecting the Yellow Line’s Andheri West station to the Blue Line’s D.N. Nagar station.
The Aqua Line (Metro Line 3) is far more ambitious. Its 33.5 kilometers (20.8 miles) run between Cuffe Parade, near the southern end of Mumbai’s peninsula, and Aarvey, in northern Mumbai. Because it’s almost all in subway and mostly runs under major streets, the Aqua Line is able to get closer to many more important places than either the suburban rail lines or the elevated Metro lines. It has stops, for example, at several clusters of business skyscrapers near the end of Mumbai’s peninsula. It also has stations at both major suburban rail terminals as well as at Mumbai Central, where many long-distance trains terminate. There are additional stops at the two Airport terminals; the new Bandra-Kurla Complex, a major commercial center; and other significant places on Mumbai’s densely populated peninsula. It complements the main suburban train lines and is being widely advertised as the “backbone” or “lifeline” of public transport in Mumbai. See the photo at the beginning of this post.
The Aqua Line is a much more modern rail line than the elevated lines. Like several other new Asian subways, it puts older metros in cities like New York and Chicago to shame. All the stations are air-conditioned and have full-height platform doors.
Boarding an Aqua Line train.
Stations are impressively elaborate. Some are quite deep. All the stations have mezzanine floors. Many stations have numerous exits; sometimes it’s possible to walk a substantial distance through tunnels that lead to particular destinations. The intricate pedestrian tunnels are important given that sidewalks in Mumbai, as almost everywhere in urban India, are often in appalling shape. They also mitigate to some extent the extreme difficulty that pedestrians experience whenever they want to cross a major road.
There are escalators and elevators in all the stations, although not at every exit. Wheelchair users are accommodated in the trains and at the elevators—although not, of course, on Mumbai’s sidewalks (which must limit the usefulness of the metro’s features for the handicapped). Also appreciated: There are (as on most new Asian metros) clean bathrooms in every station.
Escalators at the Marol Naka station.
There are elaborate electronic signs and prerecorded announcements in Marathi, Hindi, and English both in the trains and on the platforms. Trains can run driverless, although they’re apparently not yet doing so. The cars (as on the elevated lines) have open gangways. Designers have clearly been at work. Light blue (that is, aqua) is a common color on the trains.
Despite the use of driverless technology, the operation of the Aqua Line is rather labor-intensive. Many, maybe most, people buy tickets at the staffed ticket offices. You have to pass through an elaborate security system to get to a station’s entrance gates. There are separate lines for men and women; everyone is scanned by same-sex guards. Besides the guards at the gates, there are security personnel on the platforms. Every station also has cleaning staff.
The paper tickets use QR codes to open the gates. There can be backups at the gates when a train arrives and disgorges a substantial number of passengers.
Trains run frequently, something like every five minutes or so for part of the day and otherwise (I believe) at least every ten minutes.
Half of one car in every train is reserved for women. The women’s sections seem to be rather empty. Much more than in Delhi (or on new Gulf metros), women apparently feel safe enough in the main cars of the train—a good sign, I think.
The Aqua Line has been carrying something like 180,000 passengers a day.3
Inside a semi-crowded Aqua Line train.
This is fewer passengers than on the much shorter Blue Line and is actually many fewer passengers than the authorities were expecting. Outside of rush hours, trains did not seem especially crowded to me. It was always easy to get a seat.
Relatively empty Aqua Line train at midday.
Fares seem quite reasonable by world standards. The price of tickets depends on distance. It costs 80 rupees (approximately 0.88 USD) to ride the whole line. It needs to be said that this is much more than it costs to go a similar distance on the suburban rail lines.4 The fare difference may account for the fact that there has been a smaller shift in passenger loads from the suburban trains to the Aqua Line than the authorities anticipated. Many Indians have incomes that, by world standards, are quite low, and what seem like small differences in price can have a major effect on what people choose to do. One consequence of the difference in fares is that passengers on the Metro are much more likely to be professionals or white-collar employees than the passengers on the suburban trains. Or so it seemed to me.
The Aqua Line connects with several other rail lines as well as with hundreds of bus lines. Several new metro lines are under construction, and, as these open, the Aqua Line will have even better connections. One problem here though is that there is, as yet, no fare integration in Mumbai. Even when you’re changing from one metro line to another, you have to buy a new ticket. Thus, long trips that require several lines can end up being, in local terms, rather costly. There is now a phone app (Mumbai One) that, in theory, allows ticket purchase on the Metro, the monorail, suburban rail, and some bus lines, but I don’t believe that users get a discount if they transfer.5 Perhaps this will change in future years.
Despite this caveat, I was quite impressed by the Aqua Line. It provides state-of-the-art, comfortable, and speedy service in an urban area where high-quality public transportation has been in short supply. It’s the product of a new, modern India.
- It’s very hard to compare passenger loads on the world’s suburban railroads, since you encounter definitional problems of several different sorts. It’s typically impossible to be absolutely sure where suburbs begin and end, and it’s often hard to distinguish suburban lines from long-distance and purely urban ones. If the table of suburban and commuter rail lines in Wikipedia is to be trusted, it seems that Tokyo’s lines carry something like twice as many passengers as Mumbai’s. Kolkata’s suburban lines rank third, well behind Mumbai’s. Suburban lines in Paris, London, Moscow, New York, Buenos Aires, and Osaka carry many fewer passengers.
- See the famous photo of Churchgate Station by Sebastião Salgado—and also: Craig Moore’s comments at the bottom of the Mumbai page on the Urbanrail website.
- See, for example, Richa Pinto and Manthan, K. Mehta, “1/3 of Metro 3 users on CSMT-Cuffe Parade stretch, traffic eases on SoBo roads,“ The Times of India (11 December 2025).
- The suburban lines do have a First Class, for which tickets are much more expensive than on the Aqua Line. There are also extra fares for the few air-conditioned trains.
- The software is apparently quite buggy. I didn’t have an eSIM in my phone when I was in India and couldn’t test it.