Well you're at a college. If you want people to follow rules, be more specific, or don't get pissed when they follow the stated rules but you feel like the rules should include something else.

If the concern is liability, then don't just say "don't skateboard" and get mad when people bike through the area. You said no skateboards. This is not a skateboard. Rules=followed.

If anyone feels like chirping in with "you know what they meant" that really doesn't matter. Not to me, not to people who don't understand that sort of thing, not to courts.

Besides, I feel like clarity is some thing you should strive for at a facility for higher education.