How is traffic count data collected?
Vehicles are counted by the Tennessee Department of Transportation (TDOT) in all 95 counties in Tennessee, each year. Mechanical traffic counting devices are deployed along the roadside (usually secured to a utility pole) and a rubber road tube is placed across each traffic lane. Pressure from vehicles crossing the rubber tube is detected by the mechanical counter (a small box comparable in size to a car battery) and electronically stored by the counter. The road tube counters are placed on a section of highway for a minimal 24-hour period then moved to another location. The collected data is then sent to TDOT central offices in Nashville for processing. The raw counts are then adjusted using a formula to calculate the Average Daily Traffic. This adjustment takes into consideration weekday and time of year variations.
