I have often took it on my self to close a lane if I felt the threat of doing damage or hurting some one is to great. I use plenty of cones, and signs(men in trees). I sometimes park a truck in the cones to protect the groundmens doing their job from a drunk driver or some one texting. I have never had to get a permit, though I think your suppose to.
On some jobs I have used flagmen too if the need to stop traffic is there.
One thing I have learned, people are idiots, and if you don't look after them they'll get confused. Don't leave any thing to chance. keep the cones close together or they'll drive throw them, Give them plenty of time and distance to figure out whats going on. It's easy to cause an accident, and I bet the liability would fall on whoever block offs the street or lane.