Collapsing platforms

I'm doing some stuff with the airboat, but I haven't been able to get the supports under the platforms to disintegrate correctly when I drive through them...I tried setting them to be func_breakables that broke on pressure, but they seem pretty solid to me...ouch. Anyway, any ideas and/or concepts as to what to try that would be realistic? Thanks.

I don't know why it isn't working but you could just give the
func_breakable a name and then create a trigger_once around it, targetting
it.

Edit: On second thoughts, this isn't really optimal as the player is
sitting back a bit in the boat. I'll see if it works when I do it.

Yeah, uh, nevermind I was doing something retarded I guess. Don't recall exactly what I changed, but it's working fine now. Just normal breakables...hmm, actually, now that I think about it, I think it was because I had "Break on Pressure" enabled it wasn't working. I think that would be, say, the player stepping on it. So, yeah, it's working now. Thanks for the comment.

On a side note...if you break the supports up into a func_physbox (motion disabled) for the top half and a func_breakable in the bottom half, you can't parent the breakable to the phys_box...makes it unbreakable to the vehicle >.< ask me how I know. So I think I'll just have to have the broken breakable to parent the other breakables to their corresponding physboxes an instant before enabling motion on the physboxes...