That's not a Metrobus route number. . .

Ah. An MTA bus.

The timetables are interesting. It's conceived as a commuter bus, so I'd expect it to run a little more frequently at rush hour and a little less frequently otherwise, but apparently not. And the way it's staggered--five hours in the morning where there's buses to BWI but not from, and four hours in the evening vice versa--makes me wonder where in their fleet they're pulling the buses from. They can't be planning to just run them empty one way.