This reminds me of a rather disturbing realization I had a few years ago. In places like the Bay Area, it would take only a small handful of non-violent protesters to completely shut down the major transit systems (aka the roads). All they'd need to do is to slow, stop and then park 3-5 cars in strategic places on 880, 80, 85, 101 and 280 and walk away. It would be mayhem.