[hamburglar]

I must not understand his methodology, because if you're willing to meet at an interim stop (as in the examples above), then it's easy to save quite a bit more than $2.05 just by swapping with someone who is taking almost exactly the opposite route as you.

For example, if you're making the long trip from San Bruno to North Concord / Martinez, that'll cost you $6.95. If someone is traveling from Pittsburg to South San Francisco (almost exactly the opposite route), then that would normally cost them $6.70. But if you notice that their destination is one stop from your starting point, and vice versa, then you can meet up at any station in between and swap tickets, so the ticket you started with travels from San Bruno to South SF ($3.10) and their ticket travels from Pittsburg to North Concord / Martinez ($1.85). Instead of paying a combined $13.65, you pay a combined $4.95.

What am I missing? Are those twitter data scientists just not that bright? ;)

[Aloisius]

Orinda => Pittsburg is going the same way and on the same line as Walnut-Creek => Pleasant-Hill, Walnut-Creek => Concord and Pleasant-Hill => Concord (the East-bound Pittsburg Bay Point train). There is no need to get off the train in order to swap tickets.

You are of course right though that you can save far more money if you do get off and swap with someone going the opposite way, but then you have to wait for another train. If you already get off the train in order to transfer (say you commute from Pittsburg to Fremont), then swapping cards with someone going the opposite direction is easy.