GSP - There are signs prohibiting motorcycle parking, but the airport authorities do not enforce the prohibitions. It's probably just a liability thing: if your bike is damaged or stolen, we told you not to park here.

IAD is one of those airports where parking in a regular car space is permitted, but the automated gates will not open for a motorcycle (and there is not enough space to maneuver around). I tried and failed at daily garage 1, then tried and failed again at daily garage 2, but the exit gate at garage 2 was a attended and the attendant saw me and ran over to give me a ticket (at regular car rates, of course).

TRI - There are signs prohibiting motorcycle parking, but the airport authorities do not enforce the prohibitions. It's probably just a liability thing: if your bike is damaged or stolen, we told you not to park here.