This is interesting, I look forward to reading more. But I think it’s wrong, if you want to represent reality.

Real cities were all built in the past, for older vehicles, which moved at different speeds, and were controlled by drivers with different goals from today’s drivers.

So, if your game has bad and unsafe road designs, which have been partly retrofitted to reduce the worst problems, then that is accurate.

A game with optimal roads is not an accurate simulation of reality.

A professional modern road designer will simulate the expected movement of vehicles through a new or redesigned road, to try to discover major problems.

They look for problems with turning radius, visibility, stopping distances, and interactions with other road users.

I believe that a game designer could offer to do the same.

The game could draw a good algorithmic road shape first. But next offer the player an option to run a simulation of individual traffic movements, to discover serious issues, and let the player know about problems.

To the OP, I suggest this simulation approach, not trying to discover flawless algorithms. That’s not how it happens in the real world.

Several comments have suggested similar issues.