Agreed. Also on the personal level, while it could save you some money, you're not only offsetting mass transit funds to the taxpayers (or other passengers), but also taking a risk that the card you are trading for is from where they say it was from and that it contains the amount of money the other person claimed.

You're also potentially (haven't thought through all of the details yet) losing out on the convenience to tie your Clipper card with your credit card, take advantage of BART high value cards ($64 value for $60), and being able to take advantage of paying for transit in pre-tax dollars.

And unless this could be made very simple, you're going through a lot of daily stress just to save a very small amount of money which can distract you from doing things that give you more value.

>Also on the personal level, while it could save you some money, you're not only offsetting mass transit funds to the taxpayers (or other passengers)

I know people felt personally slighted with the Google Bus protests, but with stuff like this it's too easy to criticize "valley behaviour".

There isn't even much technical ingenuity here. I'm not sure how this is even noteworthy. You save $1 between two people? So you split it for a lousy $0.50 or maybe $100 per year? Just stop drinking lattes and you'll save that in a month.

Not to mention if you live further away, you deserve to pay more to make up for the extra resources needed to move you around, as nchuhoai said.

The best route appears to save $2.05 each direction according to https://github.com/asifhaque/transit-arbitrage/blob/master/d...:

  [orinda => pittsburg] + [walnut-creek => pleasant-hill]: 2.05 (35.6522%)
  [orinda => pittsburg] + [walnut-creek => concord]: 2.05 (35.6522%)
  [orinda => pittsburg] + [pleasant-hill => concord]: 2.05 (35.6522%)

Though who knows if anyone actually takes these routes. And remember many of the places BART goes aren't exactly filled with people with large disposable incomes who can stop drinking "lattes" to make up the difference.

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? ;)

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.

It assumes that everyone has the same starting balance also, so the most efficient would be a crosspairing of commuters within the turnstiles at each destination. Way too complicated but maybe a fun thought experiment.