It's a conventional data channel. No encryption. As far as I knew, it was legal for me to monitor any channel without encryption.
But since you asked...
It is one of the two data channels used by my local transit authority. I know that it at least gets signpost information as each coach passes it. It might have more data, that's part of what I want to find out. If it turns out its feasable to get location information for each coach, I'd write a program that parses this info and spits it out in a usable format so that it can be mapped. This application
already exists, but with a very clunky interface. I've already written my own program that will display all coaches on a particular route, but its limited to one route at a time (due to speed). Also, it does not track buses headed towards a base, and has limited support for "to terminal" (AKA "not in service") coaches.
So there you go. Mostly it's because of curiosity of what's on the data stream, but if I can turn it into an interesting project--cool.