By Matthew Kopas
Matthew Kopas of the University of Washington wrote a thesis on Gender Neutral toilets back in 2012.
In the United States, gender separation is the norm for public bathrooms. As one of the few remaining public spaces that are regularly explicitly segregated by gender, bathrooms are often experienced as sites of symbolic and physical exclusion by transgender and gender non-conforming people.
While the context is American, the underlying logic applies wherever you are.