Divalent wrote:Those sharp angles focus the energy on any body part that hits them to a very small area, and so result in much higher forces than would occur if the impact energy were distributed over a larger area.
You are exactly correct, Divalent.
Without expanding the overall size of the box (so that existing boxes can be retrofit), I think there's still room for a solid-material insert on each wing of the box - to flare it (round the edge) so that it's not such a sharp edge. This could be done by simply making the angles of the side panels less obtuse (so that the dimensions of the slide plate don't change much at all). I don't think this would be much more difficult to plant the pole into at all, but of course this would require extensive testing and verification.
I would NOT flare the edges around the bend cavity of the box in this same way though - because the potential for interfering with the normal action of the pole - both in planting the tip onto the strikeplate, and in bending the pole - are too great. But that's a very small area (albeit the most critical area) compared to the sharp edges along the "wings" of the box.
I think a combination of flared edges (using a solid material) along the wings of the box, combined with a box collar meeting the ASTM standard would be optimal. This can be staged over time - the new box collar now (for 4-8 more years), then the flared box inserts later. And it can all be done as a retrofit of existing boxes - without narrowing the box much at all. But for now, the ASTM standard box collar is a GREAT improvement!
I don't think the area OUTSIDE of today's box dimensions should be flared. Besides being impossible on a retrofit, this would effectively make the hard surface area WIDER (on each side of the box), which would give vaulters less flat space to land on during an aborted vault. Whether they're landing feet-first or back/head-first, it's important to keep the overall size of the box as small as possible. Flaring each side would effectively enlarge the box. The new box collar does a very good job of REDUCING the size of the box!