Urban road classification is hard. OSM’s highway=* classification scheme is defined nebulously using “importance to the road network”, and the examples given to illustrate importance are often more suited for rural roads. Generally, road classification seeks to identify the important destinations in an area, find the routes that best link adjacent destinations, and rank these routes based on the importance of the destinations. But this is difficult in urban areas, where there are often many closely packed destinations, and many parallel possible routes. Since the distances covered are often short, a local may choose a different route between two destinations based on the time of day, expectations of traffic, or simply on a whim, without great time differences. However, a hierarchical road network certainly exists in all cities, though it may not be entirely apparent to a non-local, or even a transplant until they’ve lived somewhere for many years.

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