I came across this interesting article in Railway Age (Yes they do publish articles other than moaning about Amtrak and its food service) https://www.railwayage.com/passenger/the-best-ticket-is-no-ticket/ Interesting article on the evolution of fare collection systems towards off the shelf systems that are easy to integrate with other systems and yet can be deployed and operated with less expense than legacy systems. Some early examples in the US include Portland MAX, Denver RTD and even Chicago CTA among others. A very large example in the process of being deployed is New York's MTA which is in the process of deploying a system that comes with all the features that London's Oyster system has packaged in it. NY MTA can choose to use whichever of those features it wants to use and not use the ones it does not want to use. But they can now easily accept payment through contactless cards, AFC enabled Smartphones and such, essentially out of the box, instead of doing their own custom development. Thought some might find it interesting... Incidentally, Amtrak uses a ticketing system with some similar features, but developed in house, and less capable of integrating with other related Apps that is described in the article. Incidentally I have actually used an early deployment of the NY system at Union Square. Used my Apple Watch and the payment at the turnstile was pretty much instantaneous. Not surprisingly the experience was exactly the same as in London using their Oyster system with my iPhone. Afterall both are based on the same platform. London does some really nifty stuff like collecting fare only upto the Day Pass fare and then cease collecting any additional fare for the rest of the day. That is particularly complex in London with its 7 zones and different fares before 9am and after, together with all the possible inter-zone fare combinations.