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 2011, wsdot calculated that the busiest section of sr 513 was within the university of washington campus, serving 41,000 vehicles, while the least busiest section was its northern terminus at magnuson park, serving 14,000 vehicles. the entire route of sr 513 is part of the national highway system, identifying it as important to the national economy, defense, and mobility.