Graph Simplification Solutions to the Street Intersection Miscount Problem

Street intersection counts and densities are ubiquitous measures in transport geography and planning. However, typical street network data and typical street network analysis tools can substantially overcount them. This paper explains why this happens and introduces solutions to this problem. It presents the OSMnx package's algorithms to automatically simplify graph models of urban street networks – via edge simplification and node consolidation – resulting in faster, parsimonious models and more accurate network measures like intersection counts/densities, street segment lengths, and node degrees. Then it validates these algorithms and conducts a worldwide empirical assessment of count bias to quantify the motivating problem's prevalence. A full accounting of this bias and better methods to attenuate misrepresentations of intersections are necessary for data-driven, evidence-informed transport planning.