Building Alternate Berlin

I'm a little confused by the roadways. Why do you have 2 roadways parallel to each other, when they're not one-way?

Well, there are a few things I would suggest to fix the development problems and the commuter problems you're having.

The first is there are no major thruways. You have small roads that can only handle a certain capacity. You need to upgrade these to one ways and avenues to increase the capacity of commuters on the streets and this will ultimately increase the capacity of commerce and population your region can hold. In addition to this, are the roads connecting your residential areas to your commercial areas adequately? Most cities have highways connecting the suburbs from the central business districts. You don't appear to have any of that. What seems to be going on is you have your roads placed at random. You can really see this in your second to last picture--roads are dead ending and turning all over the place, its not conducive to a smooth flowing traffic pattern for your region.

PM me and I can give you some more tips, I love planning roads for my cities. I am a regional planner in real life, so its one of my specialties.

The doubled streets were originally to allow in-street mass transit. I've since added the road top transit mode so I don't need them for that (well, not often- RTM stops do have a few quirks with road access) but I'm not ripping up the ones I have and sometimes I still build more as I has a variety of things to do with the medians.

Generally my roads are fine for my current density. I actually have little trouble with traffic. Actually, I could probably use more traffic for commercial development. The mess of roads in the last picture was an attempt to stop the commuters from another town from crossing the tile to exit other routes out which actually didn't lead anywhere. It was not adequate - the thousands of commuters cheerfully plowed right through the mess to get on an avenida going out.