Late-summer construction projects will force motorists to detour in Bellevue, South Seattle, Monroe and across Highway 520 at various times this weekend — and that’s only a warmup for worse congestion likely the following weekend when northbound I-5 constricts to just two lanes passing Lake Union.
- The westbound Highway 520 floating bridge will close from 11 p.m. Friday to 5 p.m. Saturday while concrete is poured near the west shore of Lake Washington. The foundations are being set for a connection that will link the new floating bridge in 2016 to the old highway near Montlake. Eventually, these temporary lanes will be incorporated into the permanent west connection, as shown in blue below. About 40 trucks delivering the concrete need to use the old 520 bridge to reach the pour site, said spokeswoman Debera Carlton Harrell. The bridge will reopen westbound late Saturday afternoon, helping Sounders FC fans to drive or bus into Seattle.
- The northbound ramps from I-5 to the West Seattle Bridge, lower Spokane Street, and to Beacon Hill via Columbian Way South will close from 7 p.m. Friday until 5 a.m. Monday for repair of expansion joints between bridge spans.
- In Monroe, the onramp from Main Street to westbound Highway 522 is closed so a new ramp can be built en route to a future roundabout, at 164th Street Southeast. The closure runs until 5 a.m. Monday.
- And in Bellevue, the state will close up to three lanes of northbound I-405 from 8 p.m. Saturday until 10 a.m. Sunday so that concrete road panels can be repaired.
Besides the urban detours, the North Cascades Highway and Chinook Pass are closed by mudslides, as is Icicle Road near Leavenworth.
Friday the 13th will bring much harsher congestion when the state closes two lanes of northbound I-5, from Olive Way to Lakeview Boulevard East, to repair expansion joints and broken concrete. That closure will start Friday night, Sept. 13, at 9 p.m. and continue until 5 a.m. Monday, Sept. 16. At the same time, Highway 520 will close in both directions from Montlake to I-405 while workers set more concrete foundations and shift the road lanes from 11 p.m. Friday, Sept. 13, until 9 a.m. Sunday, Sept. 15.
Below is a state Department of Transportation diagram showing the work phases on western Highway 520.