yes, but again, once one single person stops, everyone on the highway is SOL, as sooner or later that blockage will just keep growing.
If a crowd wants to swarm a highway, all it really takes is just one driver to do it. One lane comes to a standstill, the adjacent lanes are slowed by various means, people push past the first lane into the next, and in a matter of minutes, the highway is closed.
I don't know about the rest of you guys, but if i'm running down a highway and there's a solid stoppage on either side and I don't know why, it's just an automatic response to slow down in anticipation of whatever stopped that lane. Then, all it takes is some bonehead jumping out in front of my slowed vehicle and another lane is closed.