Traffic Lab is a Seattle Times project that digs into the region’s transportation issues to explore the policies and politics that determine how we get around and how billions of dollars in public money are spent.

Seattle-area drivers face a double-shot of delays this weekend as the Washington State Department of Transportation closes northbound Interstate 5 and both directions of Highway 18 simultaneously.

The I-5 disruption wraps up this summer’s repaving of the Ship Canal Bridge, where crews are refurbishing a 900-foot-long, two-lane segment on schedule.

Meanwhile, Highway 18, the main corridor between South King County and Snoqualmie Pass, will be blocked by maintenance and construction just south of its connection with Interstate 90.

“There’s just not enough weekends in a summer t

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