The only scenario that seems obvious is if the police overreact and shoot some of the protesters.
That's a really strange thing to say. There are lots of examples of disruptive protests that have helped bring about change. As an example, take a look at:
That's a really strange thing to say. There are lots of examples of disruptive protests that have helped bring about change. As an example, take a look at:
http://www.sfgate.com/news/article/A-Decade-of-AIDS-Activism...
Includes some bridge-blocking.