In some subway systems like that in Seoul, South Korea 4G and wireless broadband is available everywhere, including on a fast moving train in a tunnel. In the New York subway system cell phone coverage is intermittent, slow and not available underground. Hence a Miami Ad School Student Project that is very similar to the Spanish QR Code Book Train but uses Near Field Communications (NFC) technology rather than QR Codes.
The video below explains how commuters would use NFC to download the first ten pages of a range of popular books while riding the New York subway. When they have finished the reader would be informed of the closest library location from which they can pick up and read the rest of the book. There are a couple of problems. iPhone users are excluded (no NFC) and 10 pages of a book is about 34kB and the largest NFC tag I have seen so far 8kB. It’s great to see students being creative but don’t expect to see this idea implemented anytime soon.