SEATTLE — One week after the Alaskan Way Viaduct closed, construction crews are still on track to finish work necessary to open the tunnel February 4.
“We continue to maintain schedule, which is really important to us,” David Sowers, deputy program administrator for the viaduct replacement program, said Friday.
Sowers cautioned that although the tunnel will hopefully be ready for traffic on February 1, the tunnel won’t open early, because a celebration is planned for February 2-3.
Crews fit the final rebar onto the new northbound off-ramp to Dearborn Street on Friday in preparation for pouring the finished slab Saturday. Once that’s done, crews can begin building the off-ramp’s barriers.
On the actual viaduct, contractors are already preparing to begin demolition work about a week after the tunnel opens. Crews have begun putting barriers in place to protect adjacent buildings, according to Sowers.
That off-ramp, which will be the only northbound off-ramp between Spokane Street and the end of the tunnel, is still scheduled to be completed about seven to 10 days after the tunnel opens. However, Sowers said the Washington State Department of Transportation is working with the contractor to see if the construction timeline can for shortened for that ramp.
The southbound mainline work was also a highlight. At the south portal crews have nearly finished the roadway out to SR 99; all that’s left is striping, which will probably take place next week during a stretch of dry weather.
“The mainline southbound is ready to go,” Sowers said.
Geofoam, a fill soil substitute, was key to keeping the SR 99 closure to just a few weeks. Crews laid down geofoam blocks before pouring concrete at several areas on the construction site, including the northbound off-ramp.
Although it’s more expensive, the Styrofoam-like substance is much lighter than soil and speeds up the process, because crews don’t need to wait for it to settle before pouring concrete, like they would with dirt. Sowers estimated if soil was used instead, the closure would have been six months long.
“The extra cost of the geofoam certainly outweighed six months of impact of no 99,” Sowers said.
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