Originally Posted by
decosse
And I see how the Tour could never could be fenced in, its openness is a big part of its identity.
Some of the automobile road/offroad races are largely fenced, or have specified viewpoints because they present too much danger to the fans otherwise.
And, I believe that France reviews every inch of the course before the race.
But, it would take a Herculain effort to fence a 2,200 mile course that changes every year, two sides, end to end. Nonetheless, they still do put up urban barriers.
They could lay a chalk line, but it would be a lot of chalk, and wouldn't necessarily prevent fans from crossing the line or holding signs in front of the riders.
I think there have been crashes in the past due to photographers crossing urban barriers, and not getting out of the way quickly enough.
The best thing to do is try to educate the fans what is and is not acceptable, and part of that may be to hold fans accountable when they violate the rules, prudence, or injure cyclists.