introduction to the volume of traffic on the Primary Road System

The Office of Systems Planning, in cooperation with the Federal Highway Administration, prepares this biennial 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 general 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.

The traffic volumes depicted in this report are derived form data obtained at 8,000 count locations during -3,  -2,  -1 and . The -3, -2 and -1 count data has been updated to reflect annual average daily traffic volumes. All primary roads were considered open to normal traffic flow, that is, roads that were under construction or carried detour routes have been estimated to reflect normal conditions. An asterisk has been placed at the right in the "Section Description" to identify where the traffic was estimated from previous years count data.

Each primary route is subdivided into sections that are listed in order from west to east or from south to north. The length of each section is governed by county lines, corporation lines, junctions, and high volume intersections. Section lengths are shown to the nearest 1000th of a mile. The route number and length of each section reflect the official road conditions as of Jan. 1, 1. Annual average daily traffic volumes shown at the end of each route tabulation represent the weighted values for that route.

Innerlegs, ramps, loops and connections at interchanges or grade level intersections are not shown in this report. Traffic volumes for these road segments may be obtained from the Office of Systems Planning, at 515-239-1323 or by emailing Ron Bunting.