> So how many exits are needed for extremely rare circumstances? Keep in mind that the bread and butter of engineering is "extremely rare circumstances". In c

> So how many exits are needed for extremely rare circumstances? Keep in mind that the bread and butter of engineering is "extremely rare circumstances". In civil engineering, infrastructure is designed with 100 year floods and 50 year seismic events in mind. Blocking the only exit does not come even close to be a rare event.