Fairly simple one that will probably be notoriously hard to track down...
Under some conditions some passenger links between stops will not be created making it function as if no passenger link exists between the stops despite there being a fully functional passenger line. The conditions to cause this either involve save/load cycling or modifying unrelated lines involving one of the stops. Symptoms are basically that the link will sometimes appear and other times not.
On the server I am frequently observing this with my aircraft routes. For example...
"(1731) Line" : Yerington International <-> Cagbury International Airport
This is a premium passenger service running high speed aircraft connecting a remote island chain with the main land. That has been operating for several months. In both airports under Details there should be a passenger link with each other reflecting that passengers can route via the premium air service. However at the time of writing this post no such link is listed for either airport.
This is not the only passenger air line that seems effected by this. It also happens sporadically for others.
It appears to be limited to passengers only. Mail is correctly listed and appears to function reliably.
EDIT:
This is a lot worse than first thought. Changing the schedule for any passenger line will delete all routing information from all airports, including those for lines of other players. This makes operating passenger aircraft lines reliably impossible as seldom will passengers even try to use the lines.
To recreate...
- Load server game. Online or offline does not matter as the issue is completely re-creatable.
- Look at routing information for an airport. I recommend Yerington International @3576,2755 as it has both internal and external destination passenger air lines operating from it.
- Confirm passenger routing entries exist using the Details view of Yerington International for both Cagbury International Airport and Millstead Airport and leave the Details window open to watch for changes.
- Can also confirm inverse entries on the related airports exist if desired.
- Select Royal Western company and open the line manager.
- Modify any passenger line. For example change the line frequency of the only tram line from 40 to 41. This line is not directly connected to any airport.
- Almost immediatly should both the above mentioned passenger routing entries disappear from details view. Passengers will no longer accumulate at any airport for any air passenger route. Any passengers that have already accumulated will still wait for their intended aircraft, however no more will come.
- All airports can be checked and all airports will be missing their passenger routing entries for air lines.
The results will not happen if paused, but one can change the schedule while paused and they will happen once unpaused.
Save/load cycling rebuilds the air line passenger routing information. This is likely why this bug has gone undetected for weeks since this happens fairly frequently on the server.