How do you identify a return trip of the second address is different? You didn't mention it, but do you also have a RiderID or something along those lines? Otherwise, let's say two riders come along. RiderA goes from LocationA to LocationB. RiderB goes from LocationC to LocationB. Now, RiderA goes home, LocationB to LocationA. RiderB follows RiderA home, LocationB to LocationA. How would we differentiate those two? It would look like a single outbound with two inbound trips and the other outbound would have no inbound.