Office of Operations Freight Management and Operations

Freight Facts and Figures 2012

Figure 3-15. Peak-Period Congestion on the National Highway System: 2007

Recurring congestion caused by volumes of passenger vehicles and trucks that exceed capacity on roadways during peak periods is concentrated primarily in major metropolitan areas. In 2007, peak-period congestion resulted in traffic slowing below posted speed limits on 11,700 miles of the NHS and created stop-and-go conditions on an additional 6,700 miles.


Figure 3-15. U.S. map showing recurring peak-period congestion for year 2007.

[JPEG 3.43MB, PDF 1.53MB]


Highly congested segments are stop-and-go conditions with volume/service flow ratios greater than 0.95. Congested segments have reduced traffic speeds with volume/service flow ratios between 0.75 and 0.95. The volume/service flow ratio is estimated using the procedures outlined in the HPMS Field Manual, Appendix N.


U.S. Department of Transportation, Federal Highway Administration, Office of Highway Policy Information, Highway Performance Monitoring System; and Office of Freight Management and Operations, Freight Analysis Framework, version 3.4, 2012.


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