If there was a serious emergency the police would be there, like they always manage to be there, right on the spot, whenever there is a serious traffic accident with massive traffic backup.
If there is a traffic accident it usually only blocks traffic in one direction. So if protesters only block traffic in one direction, at least for the next few weeks, what is the problem? They can dodge and weave between blocking traffic in one direction, and in both directions till the media can’t keep up and everyone gets sick of hearing the media whining about it. Fight a guerilla info war - just keep saying you always do the right thing and vassilate in practice.
ER should get cynical.