I'm creating a program that generates miniature cities.

My first step was to create the streets of the city (represented with lines). In order to do so I created a street class which grows and gives birth to smaller streets recursively. The streets then stop growing as soon as they hit another street or the edge of the world. It looks like this :

As a second step I'd like to extrude on a z-axis all the polygons encapsulated by the streets, though I'm having a hard time finding the coordinates of these polygons easily.

Does anyone know of a data strcuture that I could rewrite my program with that would make accessing the polygons coordinates easily ? I've tried to implement a half-edge data structure but it really seems like overkill.