We are off the railroad topic, but I can shed just a bit of light on the "Q." It is true that nuclear weapons were stored there on their way to and from Europe. Shipments were by air via Sampson AFB both to and from Europe. Domestic shipments to and from the production agency began as rail, soon switched to air, and then secure over-the-road transportation when air was deemed too unsafe.
The army received full up weapons from the production agency. Most of the work at "Q" could be categorized as surveillance not involving nuclear components, although some replacement of limited life components did occur there as well as at forward deployment sites. Anything beyond that was sent back to the production agency for re-work or repair.
Since control of the nuclear weapons remained with the production agency for their duration, this agency also proscribed the security requirements for the "Q" area. And they ran frequent unannounced black hat exercises against the "Q" security force, including insider scenarios. I can say with some degree of confidence that the security at "Q" was always at least as good as Fort Knox.
And now back to our regularly scheduled programming.
Poppyl