Crowd Sourcing and Visualizing Prayers
There's nothing like visual communication to capture the thoughts of the masses and spread the word. These bright prayer flags were actually used in the context of a Methodist church congregation, but you don't have to be religious to have prayers. Being able to see these messages of hope, especially for women's safety, allows those who feel unsafe or alone in their worries to create a sense of hope and community among each other, regardless of whether they ever meet anyone else who posted a prayer. Urban areas are great for these kinds of things that require a small input from many to make it effective in telling a story. It's also easy to do (you can make it from any kind of scrap material), so it's a powerful, yet cheap billboard!
Raising awareness about all the stories where women feel unsafe in their local environment may be the first step to creating an intervention. Collecting these stories can also be a laborious task, so why not crowd source them and create an public advertisement for the issue so that it creates a conversation starter in the local places where people congregate to be social? Public manifestations can be useful because they make the act of tallking abou these issues more accepted. You can view a description of the orignal application