Old Benson Road overpass in Renton gone by 10 a.m.; freeway still closed through Sunday morning

Demolition of the old Benson Road bridge over Interstate 405 was completed by 10 a.m. today, although the freeway will remain closed as planned through Sunday morning to haul away debris and for more freeway work.

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Demolition of the old Benson Road bridge over Interstate 405 in Renton was completed by 10 a.m. today, although the freeway will remain closed as planned through Sunday morning to haul away debris and for more freeway work.

Mid morning, traffic was still flowing fairly routinely on I-5 and I-90, the regional detours around the freeway closure. But parts of the detours through Renton, including Grady Way, were moving at a snail’s pace.

The state is expecting the heaviest traffic congestion on the region’s freeways, including State Route 167 and State Route 520, between 10 a.m. and 7 p.m. Saturday.

About 145,000 vehicles use the I-405 corridor through Renton; the state is hoping that about 100,000 of those vehicles will detour from I-405.

The freeway is closed between SR 167 and State Route 169.

To remove the old Benson Road bridge, the state transportation department began a series of lane closures of I-405 in both directions starting at 2 a.m. Saturday, culminating with the complete closure by 2:45 a.m.

The freeway is expected to reopen by 11 a.m. on Sunday, following the 33-hour closure.

The bridge demolition began at about 4:20 a.m., using giant claws and jackhammers attached to heavy equipment to dig into the bridge’s center. Double-long dump trucks stood by to haul away the debris cut into manageable chunks.

The earth vibrated from the work. Water was sprayed onto the bridge to help control dust. Steel rebar that gave the bridge its strength stuck out everywhere.

The freeway itself first was covered with a bed of sand to protect its surface.

There were “no surprises” with the demolition work as of 9 a.m., Kory Voldman, deputy construction manager for I-405 Corridor Design-Builders.

“It’s all going well,” he said.

Alan Brown, the project manager for I-405 Corridor Design-Builders, said between 50 and 60 pieces of heavy equipment are being used on the project, with about 120 people working this weekend.

The equipment and workers are being used on 12 projects on the freeway. The work also includes replacing concrete panels in the freeway, installing sign bridges and doing some repair work on a City of Renton sewage line under the freeway.