 The highway is maintained by the Washington State Department of Transportation (WSDOT), which conducts an annual survey on the state's highways to measure traffic volume in terms of average annual daily traffic.In 2016, WSDOT calculated that the busiest section of the highway, near I-405 in Renton, carried an average of 43,000 vehicles per day.The least traveled section of SR 169, located at its southern terminus in Enumclaw, carried only 7,700 vehicles.