( My English is bad , but still wanna share my great idea )
1) I strongly suggest to add a "P****enger Loss Rate" to the game.
The formulation of "P****enger Loss Rate" should base on, the number of full load trains have p****ed the certain station to p****enger's destination.
So after a certain period those unhappy p****enger will leave the platfrom, and increase the number of "P****enger Loss Rate" .
According to real world no one might wait in a station for couple weeks for bus or train , and that is nonsense.
Also "Avoiding Crowded" is neither realistic nor good enough ,instead, it might crash our transport system one by one too.
I think that is a bug that, while we satisfy our p****enger better; cities grow faster, and this make impossible to play the game
2) The "P****enger Loss Rate" could be using for reduce cities develope rate.
If the number of the Rate higher, the developing of the cities will slower. I suggest the number reach 75%, cities stop growing anymore.
(http://i269.photobucket.com/albums/jj59/ar3man/1939006.jpg)
(http://i269.photobucket.com/albums/jj59/ar3man/show.jpg)
This my Route map of my Rail System, is just 30% of map coverage and it has extend a lot of time, and still crowded...
Simutrans is a balance between simulation and game.
Meanwhile, you might want to check out Simutrans Experimental, which is... well.. a version of Simutrans with some differences that, if I recall correctly, include p****engers giving up and leaving.
http://forum.simutrans.com/index.php?board=53.0
Indeed - and the "unhappy" graph in Simutrans-Expeirmental is used in a very similar way to the way in which you describe the "p****enger loss rate" in your suggestions :-) The "avoid overcrowding" is also rather different in Simutrans-Experimental.