After creating the road system, now the traffic system has to be programmed.
First conceptual drawings for the traffic system:

The goal was to create a self-connecting traffic network, which should work for left- and right-hand traffic.
Everything went fine until the cars had to drive around corners.
But a little bit later (and with some vector calculation) this also works very well.
A view of the transport system in the editor. The red squares and red lines represent the center lines of the street.
A first animated video
When creating the city map system for the new game I decided to use a block size of 10 meters x 10 meters.
First conceptual drawings for the road system:
I have set The level of detail of the pedestrian-map to 50 cm x 50 cm. Both together should allow a fairly high degree of flexibility when auto-generating the maps without too much memory or processing power needed.
For tests of the pedestrian system a simple road forming a closed loop should be optimal:

For debugging purposes it is useful to draw logical information (e.g. places a pedestrian is allowed to walk) on the screen. In Unity3d this is very simple to handle using the OnDrawGizmos functionality.
On the green areas, the pedestrian are allowed to walk:
The next step will be to design the traffic system.