I have noticed quite weird behavior on the Stephenson-Siemens game.
Suddenly "Peache Quay" became overcrowded by over 1000 passengers, all wanting to go to (or via) "All pettingstone". I was not able to cope with that amount, but at the turn of next month passengers dissapeared, and moved to nearby "Peach Central Dock" of another player. Both players have docks in All pettingstone, also quite near of each other, and the line capacity between Peache and All pettingstone is also similar for both players. I thought it was just a temporary glitch due to connect/disconnect or loading the game local, but the graphs on both docks show it is long time situation. See the scrrenshot:

Maybe it is because the waiting time gets very high due to overcrowding and low capacity of the line, so the passengers move to the other stop, causing overcrowding there. Then the waiting time average gets better on one stop and worse on the other, and when the meet, passengers will change stations again. Added screenshot with travel+wait times on both stops. Compare mail and passengers, both should be the same, but mail is unaffected by overcrowding (as there is not so much mail):
