This is such a clever way for making on the spot random cities.
I really like the idea of the dice deciding which places join up too. Although it is obviously meant for this perticular setting. With a few changes to the tables this could be used for any setting.
Each dice represents a different borough. Their position doesn’t necessarily show the physical layout of the city, just how the boroughs relate to one another. You take the points of the shape on the top of each dice (well, just the points for the d4, and for the d10’s pretend they have a triangle on top), and if that leads to another dice, those boroughs are accessible to each other