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Highway Traffic Statistics 1998

Indiana Department of Transportation
Highway Traffic Statistics
1998 Publication

Annual Average Daily Traffic
(AADT) County Flow Maps
(1991 Thru 1996

Prepared By:
Division of Roadway Management
Room N808, Indiana Government Center North
100 N. Senate Ave., Indianapolis, Indiana 46204-2249
Phone (317)232-5134

The Traffic Statistics Unit conducts forty-eight (48) hour counts on all state roads in each of the ninety-two counties. In addition to state roads, this unit also counts non-state rural and non-state small urban Highway Performance Monitoring System (HPMS) road sections, and a few non-state city streets and county roads. Each county is counted on a rotating schedule of approximately three (3) to four (4) years.

Each of the maps that follow shows a county, the state roads contained in that county and a number-letter code which has been assigned to various segments of the state roads. A listing is provided to the right of each map. This listing shows the state road number, the number-letter code that corresponds to the map, the traffic volume estimated as AADT, and termini points to which the estimated AADT apply

To arrive at the estimated AADT, a forty-eight (48) hour traffic count is averaged to a twenty-four (24) hour daily traffic figure. Since 1988, an axle adjustment factor has also been applied to correct the axle counts to vehicle counts. This vehicle count figure is then adjusted by multiplying it by a monthly seasonal variation factor to annualize the vehicle count into a 24-hour Annual Average Daily Traffic (AADT) estimate. All AADT counts on a specific state road are then compared, and termini points are established when the AADT counts on a section of road vary by more than ten (10) percent.

These flow maps provide a clear, concise way to disseminate traffic information on the State Road System. The maps in this publication also represent our latest counts which are through 1996.