A while ago I posted a simple airgate for free here but since then I've improved it by reducing it's poly count and realism. They were made for a B&M hyper but you can try using them on other rides....but they must be a single row. I do have a double gate in the works for you as well so you can use the same style gate on an intamin or something.
If you have sketchup I highly recommend that you use that file because they're easier to edit than the 3DS import.
Sketchup file: (Contains full set of gates [8 rows] that are easily removed) http://dl.dropbox.com/u/67178604/Airgat ... mplate.skp
3DS: (just one gate that you can import and position manually) http://dl.dropbox.com/u/67178604/Airgat ... mplate.3ds