A map of every intersection and dead-end inside the Beltway, color-coded by type. Image by the author.
Recently, Bloomberg Citylab featured my maps of intersections in US metro areas. Their article didn’t include maps of the Washington region, so here’s a comparison of intersections in different parts of our area.
Why intersection types matter
Street networks are an important part of urban form, both for pedestrians and for public transit. In traditionally gridded cities, like New York, a regular pattern of long, straight roads provides natural routes for buses and good connectivity for pedestrians to get where they’re going without taking indirect routes. When three-way intersections predominate, buses often have to follow winding, indirect routings to serve communities — for example the A22 in Prince George’s County — or many routes overlap on the small number of straight through streets, such as Rte 7 and US-1 in Northern Virginia.