I've got to agree with speedfreak, sand traps are in a similar vein to catch-fencing, an admirable idea but one that works out not to work very well in many situations, for example if you're heading straight-on across a gravel trap, the chances are that the wheels and underside of the car will simply skip over the surface rather like skimming stones at the sea-side, go in sideways and you'll dig in and stop very quickly, so as far as LFS goes it's faily realistic to assume that if you come off at speed it'll be the wall that stops you, where LFS falls down is the sideways issue, i'm not sure it makes
that much of a difference if you're sideways or not,
A lot of modern circuits are taking the philosophy that it's better to have a solid runoff so at least you stand a chance of stopping under control, and besides you don't get gravel all over the place when is all goes wrong
Hay bales work quite well tho'