There is no universally accepted definition of traffic congestion. In reporting to the federal government, the states have in the past used peak-hour traffic volume-to-capacity (V/C) ratios, as calculated in the Transportation Research Board’s Highway Capacity Manual, as a congestion measure. Through 2009, the Federal Highway Administration (FHWA) summed up these V/C calculations to determine the state mileage in various V/C categories. Since 2009, however, these tables have not been published by FHWA. Instead, FHWA has been reporting periodic statistics based on travel delays from mobile devices, but only for selected regions and roads, not for states.
Peak Travel Time Hours Spent in Congestion Per Auto Commuter
24th Annual Highway Report
This change by FHWA has necessitated changes in this report’s state-level congestion metric. The 22nd Annual Highway Report used a congestion metric derived from the Urban Mobility Report, renamed the Urban Mobility Scorecard (UMS).5 The 2015 UMS was published jointly by the Texas A&M Transportation Institute and INRIX in August 2015, and reported data for 2014. The congestion measure selected, the average annual delay per auto commuter (in hours), captured delay in all three dimensions of congestion. It also had the advantages of being straightforward and relevant to the average citizen, was easily calculated, and was more current. Unfortunately, the UMS has not been updated and INRIX has changed the methodology for some of its internal metrics.
As a result, the past two Annual Highway Reports use data directly from the INRIX Global Traffic Scorecard. This report uses 2017 congestion data.6 The metric selected was the “peak hours spent in congestion per auto commuter annually.” This measure, straightforward and relevant to the average citizen, is taken directly from the INRIX Scorecard and uses real-time traffic data.
For 2017, INRIX defines congestion as a speed below 65 percent of the free-flow speed, which is the typical uncongested speed on that road segment, and defines peak hours locally based on the actual driving habits in each city, as opposed to the more typical fixed peak periods of 6:00 AM–9:00 AM and 4:00 PM–7:00 PM. (The INRIX data, which are computed only for selected cities, are extended to all U.S. metropolitan areas and then rolled up by state. See the Appendix for details.)
In 2017, the average annual peak hours spent in congestion in the urbanized areas across the United States was 34.77 hours (see Table 15, Peak Hours Spent in Congestion per Auto Commuter, Figure 10). Annual peak hours spent in congestion range from 7.25 in Wyoming to 70.15 in New Jersey. The congestion problem is primarily concentrated in the major cities of just a few states.
Commuters in nine states spent fewer than 10 hours sitting in peak-hour congestion in 2016. Commuters in 31 additional states spent less than 35 hours sitting in peak-hour congestion. Only the bottom 10 states exceed the U.S. congestion delay average, but their totals skew the average peak hours spent in congestion upward. Commuters in the bottom four states (New Jersey, New York, California and Georgia) spent more than 50 hours per year in traffic congestion.
Annual Peak Hours Spent in Congestion per Auto Commuter
|Rank||State||Peak Hours Spent in Congestion per Auto Commuter|
Full Study: 24th Annual Highway Report