Outside gates

I notice a few outside gates are left open during the day and I even saw one left open at nighttime. I know the repairmen are using the gates, but I wonder if they always close them when they are finished work? I think their supervisor should be responsible for closing the gates at night. I saw one gate open an nighttime and I didn't know whether to close it or not.

I was coming home from Northern Blvd. and noticed that the side gate to my building was wide open. It was about 7 PM and I don't know who left it open (maybe repairmen), but I closed it. Those open gates are an invitation to some people to enter the courtyard and possibly get into someone's apartment through an open window, etc. I think plastic signs should be put on the gates telling people to make sure they close the gate when they enter/leave the courtyard area. Anybody agree?