Here is more about the Launch Complex 39 “rubber room” bunker to which as many as 20 flight crew and pad technicians could retreat in case of an imminent explosion on the launch pad. The reinforced concrete bunker, buried in the launch pad structure, was designed to protect those inside from a 1370° C fireball, blast pressure of 34 atmospheres, and shock acceleration of 75 gravities. Survival equipment and supplies could support 20 people for up to 24 hours, presumed sufficient for the danger to dissipate and the bunker dug out to rescue those inside if all of the redundant escape paths were blocked.
At the conclusion of the Apollo program, the bunkers were “abandoned in place” in favour of the “slidewire” [PDF, see page 47] zip-line system used by the Space Shuttle and Crew Dragon launch facilities.
