NCDOT uses what are called traffic count stations to collect data for
annual average daily traffic volume maps.
In compliance with standards outlined in the
Federal Highway Administration Traffic Monitoring Guide, annual average daily traffic volume maps and reports are published annually, once NCDOT has collected data for the entire state and analyzed and processed the entire set.
With more than 44,000 portable traffic count stations throughout the state, the Traffic Survey Group usually collects data for interstate, U.S. and N.C. routes every year.
Secondary road volumes are collected every two years with approximately half being counted each year. Not all secondary roads having low volume, however, are counted.
Traffic volume data in North Carolina's 18 major urbanized areas, however, is collected on a two-year cycle:
Urban areas counted during even years are Asheville, Charlotte, Concord-Kannapolis, Fayetteville, Gastonia, Goldsboro, Greenville and Jacksonville.
Urban areas counted during odd years are Burlington, Chapel Hill, Durham, Greensboro, Hickory, High Point, Raleigh, Rocky Mount, Wilmington and Winston-Salem.