Angie Schmitt reports on a new study [PDF] that upends common assumptions about the relationship between density and congestion. The study analyzed the relationships between land use patterns and traffic conditions in four Phoenix travel corridors, including three older, high-density, mixed-used urban areas and a more contemporary, lower density suburban area.
"Comparing one suburban corridor to two of the streets in the more dense neighborhoods, the study found that on the more urban streets, traffic congestion was 'much lower,' or about half as high (measured by the ratio of the capacity of the roadway to the actual volume of cars on it)."
"How did more compact neighborhoods manage to have less congestion? It's not just because residents there drive less overall. Two design characteristics also ease traffic, according to AZ DOT. Fine-grained street networks distributed traffic evenly across the higher-density neighborhoods, while every driver in the suburban neighborhoods was funneled onto the same big arterials. At the same time, improved pedestrian conditions in commercial centers made it easier for some drivers to park once and walk from destination to destination, taking cars off the road precisely in the areas that attract the most people."
Thanks to Todd Litman