 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 2009 , WSDOT calculated that as few as 2 @,@ 000 cars traveled through the central part of the highway , and as many as 2 @,@ 500 cars at the interchange with SR 22 . 
 Every year the Washington State Department of Transportation ( WSDOT ) <a href='uninflect' title='1'><mark>conducts</mark></a> 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 <a href='drop_aux' title='2'><mark>is</mark></a>a measure of traffic volume for any average day of the year . In 2009 , WSDOT calculated that as few as 2 @,@ 000 cars traveled through the central part of the highway , and as many as 2 @,@ 500 cars at the interchange with SR 22 . 
Every year the Washington State Department of Transportation ( WSDOT ) conduct 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 a measure of traffic volume for any average day of the year . In 2009 , WSDOT calculated that as few as 2 @,@ 000 cars traveled thru the central part of the highway , and as many as 2 @,@ 500 cars at da interchange w SR 22 .