I say for the first one, Smith doesnt have enough grounds for a case. Depending on what type of rail traffic (passenger,frieght) goes through the station it should stay operational.
And for the second queston. X would do best by suing Y, and thenhaving Y sue Z, or X suing Z directly for a ddefective product. Trying to sue both Y and Z would not be in X'x best intrests because the court would most likely rule for X only against on or the other (Y or Z),not both.