Remember one thing: when you start a map with a certain ruleset, if you change the ruleset it will change in game too. For example you make a ruleset name "MyFirstRuleset", with metro capacity doubled. Then you start a map with that ruleset, play a bit and save. If you will change "MyFirstRuleset" for example with bus capacity halved, when you load that save you will see that bus capacity will be halved there, too. Even if when you started the map that rule wasn't there.