Why doesn’t a city like Mumbai have a QR code-based bus ticket payment system or even accept One India Travel card?*

When I visited Mumbai a few years ago, I happened to see a sign for a contactless transit card for Bombay Local Train at some railway station in Mumbai. From a quick glance, it seemed identical to London Oyster card, which uses RFID technology.

I haven’t seen anybody use this card nor have I heard anyone talk about it – but I haven’t taken / talked about Bombay local trains for decades.

Assuming that there’s no such card in use now, I’m guessing the RFID-based technology didn’t work out. Having used similar contactless ticketing cards outside India, and based on my cursory knowledge of RFID contactless ticketing technology for rapid transit, I’m guessing the technology couldn’t be implemented in the Bombay local train network because of one or more of the following factors:

  1. Small as it is, the latency of RFID technology is still too big relative to the crowd in a typical Bombay local train station and called for unviably large number of turnstiles.
  2. It’s virtually impossible for the ticket collector to navigate the crowd inside a Bombay local train to check the validity of the card-based ticket.

*: This is the original question I answered. I’m repeating it to help me make sense of my answer in case it’s moved to / merged with some other question that I didn’t answer.