Just in case you may ask : what it is you are worried about when you are in a city. People are around you all the time.

Well, a few years ago, when I was younger and dumber, I did spend time supervising our first home being built. I was alone inside the construction area, but had a "batman belt" carrying a cell phone, a multitool ..etc. with whistle around my neck. Something did collapse on me and I was pinned under for about 15 minutes. Wasn't too serious and I had the cell phone to call if I needed , but I freed myself.

Now, I am many years older, with poor knees and much less fitness level. I have to rely more on tools to save the day. And the most important would be a knife.