[Sir_Cmpwn]

Carefully placed raspberry pi + OCR?

[vinnycoyne]

I'd imagine that placing a "homemade" electronic device in a densely-populated, public space is going to attract a lot of unwanted attention.

[Sir_Cmpwn]

With the right 3D printed case you can make a raspberry pi look pretty benine.

[laylomo2]

From all those military guards that parade up and down the station

[InitialLastName]

You joke, but Penn Station and Port Authority are effectively occupied territory. There are at least four different law enforcement agencies present and patrolling, stopping and frisking anybody who "looks out of place", hassling homeless people, and generally making you feel "safer".

[kogepathic]

Just add the ability in the app to take a photo of the screen and use OCR to identify the train/platform.

All he'd need is one or two users to take a photo of the screen and he'd have his source of historical platform data.