City streets can be represented as graphs with crossings as vertices and roads as edges. And, naturally, that's the representation traffic routing services (like Google Maps) are based on.
These graphs can be recovered from the road layers available on OpenStreetMap or elsewhere. For example, see https://gis.stackexchange.com/questions/104452/how-to-build-a-graph-from-a-map.
Are there any repositories of the ready-made graphs for cities that would let me to avoid going through this conversion process?