Forget, you can't seriously expect the first requirement of designing and building a run-up area enclosure is to handle a runaway plane? I think the most important requirement is sound proofing. Let's be real! It is not such a likely occurence that it should be priority 1. Do you get fed up that when you drive your car, there is a concrete low wall (pavement) right next to you almost as if it is designed to take your tyres out should you strike it? This is a well designed run-up pan, such events do not happen regularly.