... little Jimmy is all set to settle in for a good night's sleep out in the office building courtyard. Notice this design of shelter has an 'L' shaped entrance. Radiation travels in straight lines and cannot turn a corner. But like a lot of American Civil Defense planning it never seems to take into account radioactive fallout dust. I guess they assume that since this shelter is designed to be built inside a basement; the house structure above will act a suitable barrier and filter for the fallout dust.