Does walkable development really lead to worse traffic congestion? Opponents of urbanism often say so, citing impending traffic disaster to rally people against, say, a new mixed-use project proposed in their backyards. But new research provides some excellent evidence to counter those claims.
A recent study by the Arizona Department of Transportation [PDF] found that neighborhoods where houses are closer together actually have freer-flowing traffic.
Researchers compared some of greater Phoenix’s denser neighborhoods – South Scottsdale, Tempe, and East Phoenix — with a few of its more sprawling ones – Glendale, Gilbert, and North Scottsdale. Some interesting patterns emerged.
In the more compact neighborhoods, the average household owned 1.55 cars, compared to 1.92 in more suburban areas. Residents of higher-density neighborhoods also traveled shorter distances both to get to work and to run errands, the study found.
The average work trip was a little longer than seven miles for higher-density neighborhoods; in the more suburban neighborhoods, it was almost 11 miles. Residents of the three compact neighborhoods traveled just less than three miles to shop, while residents of sprawling locations traveled an average of more than four miles. All of this led the more urban dwellers to travel an average of nearly five fewer miles per day than their suburban counterparts.
The density divide also played an important role in transit use. Rates varied from as high as eight percent transit ridership in high-density neighborhoods to as low as one percent in the more sprawling areas.
All of this translated into a reduced strain on roadways in the places that had more people — running counter to one of the strongest objections to mixed-use development. 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).