On Sun, 08 Jan 2012 13:26:26 -0800, Jeff Liebermann
wrote:


There are motion detector lighting systems that work this way. For
example, a local eco-friendly business saves electricity by not having
the parking lights on unless it first detects motion. The lights are
timed to stay on for approximately twice the time it takes to walk
across the parking lot. I think that's about 4 minutes.

I have to say, this sounds like the opening scene from a murder
mystery. Only cars are big enough to start the lights. The woman
parks the car, away from the entrance so other cars won't ding hers.
She walks to the store, is almost there, remembers sometihing in the
car and has to go back, and on her second trip to the store, the
parking lot lights go off, and she hears footsteps behind her. We
only see her legs and his legs, and soon they are both running.

In the next scene, there are a lot of police standing around.