The best way to describe the structure is to think of it as the basement of an apartment building. Each apartment has a parking spot. The owner of my parking spot built a garage box on it and rents it out.
The lighting outside of the box (in the underground corridor let's say) is on a 30s timer, and is either switch-activated or activated when the underground garage door opens. Inside my box there is no electricity, and no lighting. The only sources of light are this timed outside light or the daylight coming in from the underground garage door if I lock it open.