A light that waits

Nothing happens in the corridor for exactly as long as nothing needs to, and then, at the scrape of a wheel or the shift of weight on the concrete, the light overhead snaps from a dim standby glow to full brightness in under a second, covering whoever entered its arc within a radius of roughly thirty feet. It holds that brightness for somewhere between forty-five seconds and two minutes, the timing set by a technician years ago and never revisited, and then it begins to dim, gradually enough that a person standing still to read a lock combination or check a phone will trigger it again before it goes fully dark. Someone moving slowly, someone who stops often, someone unloading a car alone at ten p.m. and pausing between trips, will keep the whole corridor lit the entire time without ever noticing they are the reason for it. Someone who leaves quickly is dropped back into standby dimness within a minute of the last footstep, the corridor reverting to its low amber hum as if the visit had been edited back out of it. Storage corridors are lit only for the people currently standing in them; every other unit along that stretch sits in whatever brightness the last passerby left behind, and the light has no way of knowing which doors, behind it, have not been opened in years.

H. G. Plimsoll