Safety is dynamic and hyper local
Parts of urban environments can feel unsafe at some times and safe at others. This boils down to myriad factors such as where the lights are working, who is hanging around in a certain cafe that day/week/month, which combinations of people have started knocking around together, which part of the day/year it is. The point being that tracking things that are 'unsafe' needs to be a dynamic exercise driven by the people on the ground.
Not research specifically but an observation from our work with adolescent girls in Rwanda.