Many roads look similar, but in fact, every road is under a different amount of stress based on the vehicle traffic it transports. The amount of traffic that travels a road is a vital factor in determining how much maintenance the road requires from year to year. On way to measure this volume is using design hourly volume --- the 30th highest hourly volume for the design year, usually 20 years from the end of the road's construction.
Survey the road for one year using a vehicle traffic counter to determine how many cars travel the road in total.
Divide the total number of cars by 365 to compute the average daily traffic, also called ADT.
Multiply the ADT by the percentage of the ADT that occurred during the design hour (the 30th highest-trafficked hour in the year 20 years after the end of construction).
