But there should still be some override that would allow for a bunch of taxis to converge at one spot. Say a sporting event just got out, there's going to be a lot of people looking to catch a ride home. If you don't want all of those customers finding another ride, the system should have no problem dispatching drivers from other zones to pickup. Having a bunch of fares popup at the same location shouldn't be a major concern and it sounds like there were no safeguards preventing every driver from being dispatched. Without just adding a limit, like no more than 50% of taxis can be dispatched to a single zone, I'm not really sure how you could prevent this from happening again. I don't know exactly how the hack happened but if someone was just able to manually spam the dispatch queue directly, the only thing you could do going forward would be to place an automated check on every addition to the queue that it's from a real user with a valid credit card and that no other requests from that user exist in the queue.