In the laboratory/manufacturing world we use this thing called the heirarchy of hazards control. It defines the steps you should go through when trying to make a process safer. The heirarchy is Elimination - Substitution - engineering controls - administrative controls - ppe.
What most safety campaigns focus on is the administrative controls, or the 2nd to last step. Slogans and driving laws and things that can easily be ignored. Here, Hoboken has applied engineering controls - physical barriers that separate the person from the hazard. I guess in this case it's removing an obstructing barrier.