I am late to this because I have been at a funeral. Fortunately, I did not need to go near a motorway, but DD, who lives north of the river was caught in the logjam trying to get to an important meeting in Dartford. ironically the meeting was about getting roads flowing more smoothly, whch would, of course, help reduce fuel consumption in all petrol/diesel fuelled vehicles.
Left to myself, I would just leave the protestors where they are until they are prepared to come down. keep the roads running beneath them, just have policemen ready to arrest them when they do come down.
They are where they are as a result of their conscious choice knowing the dangers, a bit like people climbing Mount Everest. You know before you start that your project is dangerous and you might not return alive.