SimCity style roads?

I want to create a SimCity style game, found a video for SimCity Glassbox and want to create something similar … Sim City, Glassbox Engine - YouTube

The main question is how should I create a pathfinding system for vehicles and people to get to where they want to go (eg home to work), also I’ve looked but can’t find a good way to create junctions. One other thing I think a big part of a road system is the detection of non-attached roads to warn / disable destruction.

Really interested to hear peoples thoughts on this.