I have some more clarification too about this issue and what it’s affecting, in terms of out side city traffic spawning like planes (I recently unlocked it and tried it), it seems there’s a cap or a limit to how much specialized vehicles can enter.
Ex. I had about 12 tourist train stations running, all bringing in about 10 to 30 trains every 3 to 4 mins (again no traffic issues in my city in terms of train traffic) it’s seems to be there’s a limit to how many trains/planes/ships (idk about ships because I’m not close to connecting my map to a shore line yet) but just with those 2 sources of transportation it seems most likely there’s a cap to how many times a vehicle can enter and a cap to how many can leave in a certain period of time.
Another thing to note: I had so many trains coming in to my city that soon the trains started only transporting 1 to 15 tourist out of the max capacity of a train (which is like 150 or 200 off the top of my head) basically the more trains imports out side the city the less tourist riding per train.(—— I need some answers why on that.