There was an article in the Star a couple of years back , where Tony Briggs was developing a new type of barrier. It was very interesting and i'm sure he test it by riding into it. The thing is, air fences and the poly foam fences are great if you hit them right, a lot of the injuries are by the incoming bikes hitting the guys, and a great deal of injuries are result from hitting the ground at speed. Just looking at youtube footage of crashes proves there is a need for air fences in a lot of situations and they definatly have saved lives in my opinion, but I have also seen pretty tame looking crashes where nobody has been any where near the fence end up very bad.