<br/>Well, there's only one way to be sure no one is in the room. Keeping my ear to the door, I knock three times - not loudly enough for it to be heard at any distance, but clear enough for anyone in the room itself to hear. I wait a few minutes, listening for any sign of movement or voices. If nothing happens, I look to see how the hinges on the door are set up. If I think I can unscrew the hinges and slide the door out that way in 45 minutes or under, I'm going to try for it. If not, I'm going to go look for a candle or some other light source and check out the elevator shaft a second time.