Relatively simple, but relatively difficult to beat. Today's more complicated ticketing systems offer arbitrage opportunities. But the bull session suggests that the transaction costs of setting up a ride-sharing cooperative exceed the relatively small benefits to engaging in fare arbitrage.
Armed with an up-to-date fare guide, it’s simple to find out whether a particular pair of trips allows for arbitrage.A map is useful. The day service Red Line runs Millbrae - Glen Park - Embarcadero - Berkeley enroute Richmond. In principle, a pair of regular riders could discover this pattern and work out this trade although the lost time from their electronic shackles is probably worth more than $1.70.
[Twitter data analyst Asif] Haque gives the example of a commuter travelling from Millbrae Station to the south of San Francisco to the downtown station, Embarcadero, a journey that costs $4.50. Another commuter travelling from Glen Park in San Francisco to Berkeley on the other side of the Bay pays $4.20. So together they have to fork out $8.70.
But if these commuters meet and swap tickets, it’s possible for them to pay $5.10 (Millbrae to Berkeley) and $1.85 (Glen Park to Embarcadero) or a total of $6.95. That’s a saving of $1.70 or 20 per cent.
And transit authorities can tweak their prices to counter such anomalies. It does pay to be alert to them, though. Years ago, a college friend discovered that a Paisan's mushroom pizza with sausage was cheaper than a sausage pizza with mushrooms. They eventually figured it out.