Write a news report titled “Reasoned Closure: The WSDOT’s Temporary Shut Down of SR 18” that delves into the reasons behind the Washington State Department of Transportation’s decision to close SR 18 for six days starting May 15. Highlight the construction work planned during the closure, the expected impacts on local travel, and the measures in place to guide drivers during this period. Remember to include details about the broader interchange improvements and the anticipated timeline for project completion!