I've been the guy in uniform who turned up to negotiate a peaceful settlement to a transport dispute. I'm not sure why the inspector picked me to go inside the picket with him, but once there we both ended up dealing with the union. My starting points were "you want an outcome, some of this is private property, some is a road under the traffic act, but irrespective, nobody wants an injury" (trucks driving over people in the picket seemed distinctly possible) and "I'm a union guy"- which an inspector is not really (they have a separate commissioned officer union which .. is. .not like a union )
We didn't move anybody in the picket. Management acknowledged the petition. Business resumed later that day and no-one got runover. Over the next 18 months there were investigations, in various states including ours, that identified breaches of transport acts, OHS etc, by some of the contracting companies- and a couple of directors got fined. And going on, general issues with trucking law enforcement , fatigue management etc had an impact on normalising the laws across the states. (ie the transport unions had a valid point about problems in the industry)
So I'd say, don't expect police to go heavy against unions, you may be disappointed. 15 years exp.
YMMD outside Australia