The Houston Chronicle notes that METRO’s buses are only on time 61% of the time, and asks why. That’s easy. Yes, there are some avoidable reasons why buses can be late. Once, on my commute, the bus driver actually got lost. But there are two major reasons why buses times are unpredictable: traffic and passengers. The traffic is the same traffic everyone else is stuck in. The passengers come into play when there are more of them than usual or when it’s raining and they have to pause to fold their umbrellas, or if someone has to fumble for change, and a 10-second stop turns into a 60-second stop. And there’s nothing you can do about either of those things that doesn’t involve major investments like dedicated lanes or ticket machines. Local buses in mixed traffic run late. That’s what local buses in mixed traffic do, especially on long routes like many of METRO’s.

There is something else worth noting, though: cars run late all the time, too. The only way to make sure you’ll be on time to an appointment you’re driving to is to leave early. But we’re used to that. It’s also a socially acceptable excuse: I can’t begin to count how many times I’ve seen someone walk into a meeting late and say “traffic was really bad” and everyone nods.