I decided to install an improved traffic model (the NAM Z) although without anything else from the NAM. I wanted to get a simulator that would consider travel times, not basically just distance like the default model, because one of my goals is a functioning region. To me, that means logical traffic setups should get used. The rest of the NAM I left out because, for now at least, I'd like to stay as vanilla as possible. I also added the roadtop transit mod, based on suggestions from the comments. This isn't a necessary mod, but it does mean I can introduce mass transit to existing streets without major reconstruction. In this case I can be freer with village layouts as I don't have to think as much about what I'll do when I get to high density. Armed with my transit improvements, I decided to upzone the denser areas on the east and see how they worked.
I started with Schonwalde-Glien. This is a city I plan to eventually put to high density. It's laid out with an avenida grid. The city is mixed-use, unlike Konradshohe, which has residential, industrial, and commercial zones largely separate from each other. At the start, the east bank had denser development. Dirty industry is mostly in the north, and consequently the less-desirable residential development.
Regionally I've had a high demand for R$ so I upzoned northern areas. However, although there was some development, the population didn't increase. After running the sim for a while, I went to the southern area to upgrade that. It still didn't have much of an increase. Finally I added some parks and a private school and that got the population up from about 55,000 to about 65,000. I upzoned the commercial areas to get some matching jobs; most of the response was along the southern bridge, which has high traffic.
I didn't want to make the west bank too heavily developed as I have not yet put in cities to the west and north and so I need Schonwalde-Glien lightly developed on those sides to look reasonable on the region map.
Next I moved to Konradshohe. Unlike Shonwalde-Glien, upzoning the residental areas produced respectable pop growth, from about 75,000 to about 95,000. I was surprised by this, since the traffic in Konradshohe is actually quite a bit worse due to the large single-use blocks inherited from the city in the region start.
I put in a commercial zone along a bridge in the south which goes from the residential area in the west to a commercial/industrial zone in the southeast.
With my finances and demands looking better than the last time I was here, I extended the rail from Brieselang to the east through the industrial area. The demolished industry did not redevelop as it's too polluted for high-tech and my other industrial demands are negative here. I filled in the area between the original industrial area and the original residential area with greenspace, commercial, and solar plant buffers.
Finally the extra development in Konradshohe was making the border with Spandau start to look a little odd since Spandau isn't developed there. I put in a small low-density neighborhood in Spandau for a transition.
And finally here's the region shot. The increased density is noticeable in Konradshohe and Schonwalde-Glien.