HM walkers

I'll offer a little different perspective of the walkers issue.
Last year I rode on a press truck at the front of the men's half marathon, which has been the U.S. Men's Half Marathon championships the last couple years.
Walkers who had made their way out on the course early were apparently not aware there would be lead vehicles and press trucks coming through. Nor did they seem to care on a couple of occasions. We came really close a couple times to clipping a couple runners. And we also got slowed down a couple times by walkers who would not move over to let us through, therefore causing the vehicles with the cameras to come close to hitting us. In turn that caused the lead runners to get too close to the vehicles. Those runners deserve not to have their races interrupted by people walking the course.
It is not a safe situation for walkers to be on the course early.
I have no probelm with people wanting to walk a marathon. But they should not get an early start time.