one of the things they teach aircraft pilots is that there is rarely an accident when one thing goes wrong. when an accident occurs it's always two or more things failing at the same time. i'm sure in this case everyone on the crew thought that someone else had that turn covered. perhaps the biker thought so too, but got confused or was misdirected. was there one biker, or several ? was there an ATV or a dirt motorcycle on the course too ? was the biker a runner ? a cross country runner ? did the biker know the course ? i recall once at the Carlsbad 5K the lead biker was a gorgeous female triathlete who may or may not know cross running. fans have video and point-and-shoots and want to get their kids pictures. when one fan creeps over onto the course the others start creeping too. the main point is that this mishap should be investigated since it has happened several times recently over the years.
also, from my experience, when something goes wrong the officials clamp down on those who are not at fault, because they don't want to punish their fellow officials who they rightly see as teammates. instead usatf clamp down on the crews, media, and athletes. case in point, the hammer at hayward field. when a local oregon-base official got wrapped by the hammer cable, then sued tom jordan/pre classic, the crews and media were punished in subsequent years and were barred from the field, the media can no longer have good camera positions for the hammer. in 2005 an official in his 70's died at home depot at the usa nationals warmup friday afternoon practice after being struck in the head by a 16 pound shot. he had alzheimers, the california dmv had taken his drivers license away, yet usatf let him on the field that practice day. the next day, the crews and media were pruned to a minimum, but, usatf did not barr senile officials nor officials that are very elderly, shielding their own.