I think it just came to me. Out of one of the tunnels you come out of, the airport is on your left. If you make a left into the airport and then another left, you take the road and up the stairs. That's one of them. Now say you were coming out of that tunnel again but kept going straight. About 3 big streets up you have to make a left and you'll find it.
I haven't played this game in about 3 months but I'm pretty sure that is accurate.