the only thing i see with the concrete barriers is they do move. IE NOPI 2004 when a 240 smacked one at about 4-50mph and it knocked it quite a few feet. It was a "smaller" berrier, nothing like a divider wall... but appearantly they thought it was safe enough. Yeah, getting a "bigger" barrier would be correct, but then theres the cost of renting them, moving them, renting equipment to move them, renting the lot for an extra day to come up with a course and place barriers (dont think theres enough time to do it in the morning of the event). It would be easier to regulate photographer areas in the end...