Maybe urban truck traffic isn’t rising after all

By Bill Holloway
One of my posts from last year, which raised the possibility that we may be in the midst of a major increase in urban truck traffic—and the analysis by the Brookings Institution on which it was based—was recently called out as flawed in a blog post by Joe Cortright of City Observatory. Cortright’s criticism is rooted in what he believes is a faulty analysis of FHWA data due to two factors:

  1. Changing boundaries of urbanized areas, which inflates urban area vehicle-miles traveled (VMT) and deflates rural VMT as rural roads are reclassified to urban. Tony Dutzik explains the issue here.
  2. A change in the data sources and vehicle definitions used by U.S. DOT to calculate truck VMT. This change resulted in the data reflecting a 50 percent jump in urban truck VMT between 2006 and 2007.

Cortright’s comparison of U.S. DOT truck VMT data between 2007 and 2013 with the total growth in Amazon’s North American online sales shows that while online sales skyrocketed during this period, urban truck traffic remained flat. Booming online sales fail to lead to booming urban truck traffic due to increasing delivery density, which allows each truck to perform many more deliveries.
As I mentioned in my original post, online sales and home delivery are also generally believed to lower passenger VMT and total traffic levels by alleviating the need for individuals to use a car for shopping trips.
Bottom line: online commerce does not appear to be driving an explosion in urban truck traffic, and may, in fact, be driving a trend in the opposite direction.
Bill Holloway is a Transportation Policy Analyst at SSTI.