The 1930s time period that this discusses would have been very oddly early to begin construction of deep shelters, globally. I don't know a lot about Soviet Col

The 1930s time period that this discusses would have been very oddly early to begin construction of deep shelters, globally. I don't know a lot about Soviet Cold War civil defense history but Wikipedia at least confirms that dual-use construction as bomb shelters occurred during system expansions in the early 1950s, much later (and, most importantly, after the introduction of nuclear weapons). Deep shelters were not common prior to the introduction of nuclear weapons as there were cheaper and more practical defenses against conventional bombing, particularly before radionavigation (appx. early '40s). This puts the Moscow Metro bomb shelter efforts solidly a decade later than London's conversion of Tube stations into dual-use bomb shelters, which started shortly pre-nuclear as a response to the unique challenges of defending London from the Blitz (London was highly dense and radionavigation was coming into use, largely defeating blackouts as a damage control measure). The United States made various runs at similar projects from the '50s to the '80s but they never got particularly far (which is a statement that goes generally for US civil defense efforts), probably in large part because the US never actually faced bombing like Great Britain had.