Volume of traffic on the Primary Road System

The Iowa Department of Transportation's Systems Planning Bureau, in cooperation with the Federal Highway Administration, prepares this annual traffic report. This report is used by federal, state, and local governmental agencies in determining highway needs, construction priorities, route location, and environmental impact studies; and the application of appropriate design standards. The public uses this information in determining the amount of traffic that passes a given area as they make their development plans and propose land use changes. The above reflects only a few of the many technical uses for this data.

Starting in the 2010 report, traffic-volume segments include the mainline, ramps, loops, and connections at interchanges while inner legs or at-grade level intersections are not shown in the annual report.  Prior to 2010, ramps (all types of arrangements and sizes of turning roadways connecting two or more "legs") at interchanges or at-grade intersections are not shown in these reports. Traffic volumes for these road segments may be obtained from the Systems Planning Bureau by calling 515-239-1323 or emailing Jorge Zamora at


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