 This is expressed in terms of average annual daily traffic (AADT), a measure of traffic volume for any average day of the year.In 2012, UDOT calculated that as many 22,955 vehicles used the highway on an average day near its junction with 500 South, and as few as 20,240 vehicles used the highway at its southern terminus at I-215.The Federal Highway Administration classifies Legacy Parkway as a MAP-21 Principal Arterial, and as such is part of the National Highway System.