[simtel20]

Comparing an underground rail system to a surface bus system is apples and oranges.

What lets the transit app do this is a that the MTA just enable Wi-Fi and cell signals in all underground stations after a long build-out so that the data can actually be collected system wide from riders using their app.

[breeny592]

Sydney Australia has had this for several years, including through it's various tunnels. Whilst the majority of the network is above ground, the inner-city is underground. The telcos here spent a lot of money/time in getting 100% coverage through the tunnels in ~2011 though, which definitely enabled something like this.

Glad to hear that cell signal is finally reaching across the subway network - when I was last in NYC it drove me nuts not being able to just browse on my phone whilst waiting for a train.