>Didn't they manage to put a runaway GG-1 (brake failure) into the concourse and then fall into the basement of Washington, DC Union station? Wasn't there an upcoming inauguration, holiday or some special event that meant they station was going to be at maximum capacity, and they just built a new floor within hours over the wreck and recovered it later?

That was the PRR, and it was just a few days before Ike's inauguration, his first one as I recall. "Brake failure" doesn't mean the apparatus itself failed, meaning the control valves, but that something prevented them from operating (a self-closing angle cock).