The train. How did I arrive here?
In my theory; You arrived here via just a normal rail train. Old modern trains were recycled and made into citizen transportation trains. Not for daily use but for transferring citizens between cities or perhaps districts. I believe they were also used for transferring units but I'm unsure. Hl2 did not give us enough information on that subject; But it was clearly used for transport. As for razor trains. Razor trains carry pods and other combine equipment. Razortrains often only went to or came from a prison with a load of pods. They were seen in the citadel. But, there were also alot of stalkers in the citadel. I never once saw a Civil Protection unit come in contact with a stalker. However; Overwatch acted as if they were used to it. Thus creating my theory. But this can be twisted for Civil Protection roleplay.