Every year, the Washington State Department of Transportation (WSDOT) conducts a series of surveys on its highways in the state to measure traffic volume. This is expressed in terms of average annual daily traffic (AADT), which is a measure of traffic volume for any average day of the year. In 2014, WSDOT calculated that the busiest section of SR 900 was at its bridge over the Cedar River in downtown Renton, carrying 48,000 vehicles, while the least busiest section was on the eastbound lanes of the one-way pair in Renton, carrying 6,300 vehicles.