The back end of a pavement grinder on southbound I-5 in downtown Seattle on Feb. 24, 2009. The grinding process removes about a half inch off of the pavement surface to provide a smoother ride with enhanced friction. The grinding machine features diamond-tipped circular blades that are stacked together on a roller that cuts a four-foot wide section of pavement. For more project information, visit www.wsdot.wa.gov/projects/i5/seattlepavementrepair. Learn about WSDOT's busy 2009 construction season at www.wsdot.wa.gov/construction/2009.