edelamm

I've been noticing for a while that every time that any of my cities exceeds maybe 400k citizens, the usage in public transportation significantly drops (for example, at some point I have 10k users in the subway system and then in goes down to less than 5k). Does anybody know why is that? I've been trying to encourage the use of public transport by increasing the budget to 150% and setting the free public transport policy for the whole town, but it won't help. I always try to design a multi-modal public transportation scheme, and it works really well (increasing number of users, reduced traffic congestion, etc), but then this happens. I have also noticed that traffic congestion is very well controlled, even with the low public transport usage. I've been looking for an answer for this like crazy, but it seems that anybody in the internet ever has had this issue before, and it's driving me nuts.