I just had the same problem with DoC 1.15. Railway was connected from Ajan to Moscow, then St Petersberg, but nothing triggered it. I then used World Builder to build three other Siberian port cities including two in Kamchatka, connected them with their own line through the arctic, and still nothing. My only other thoughts about this are that maybe I confused the algorithm by building a road first, then building the railway mostly going west from Ajan back to Moscow. Should I have started in Moscow?
Including 1914 Auto save if anyone wants to take a crack at this...