I think this is the end part of the "Emergency Egress System" which included a slide-wire basket from the top of the vehicle support structure/gantry. Some of

I think this is the end part of the "Emergency Egress System" which included a slide-wire basket from the top of the vehicle support structure/gantry. Some of the images at http://history.nasa.gov/ap10fj/as10-image-library.htm http://history.nasa.gov/ap10fj/as10-image-library.htm do look a lot like the arched solid concrete room entrances, and there are a few of the wire system as well. I recall (on HN I think) a while back there was an article about the slide part of the system and the crazy specifications required to attain some level of plausible survivability. Edit: some more images at http://www.collectspace.com/ubb/Forum40/HTML/000164.html http://www.collectspace.com/ubb/Forum40/HTML/000164.html including the armoured personnel carrier as a last hope contingency. Edit 2: Found it! http://americandigest.org/mt-archives/american_studies/how_to_get_out.php http://americandigest.org/mt-archives/american_studies/how_t...