Noncasus posted...you need to increase mass transit like bus terminal and bus shuttles. That way you don't have as many cars on the road at once.
Mass transit can help, but some people have been able to get 400k pop without any. You have to increase the density though by satisfying needs like shopping, police, fire, reasonable taxes. Eventually the buildings will get bigger so more people will live in them. Parks will increase the wealth level of people living there which will demand medium and high wealth shopping. I do think that parks help increase density also by satisfying them.
---
Brushes with death are like snowflakes; each one is unique, and if you have enough of them you can make a snowman.