Wednesday, December 2, 2015

We’re ringing in the new year with a new SR 520 off-ramp

By Steve Peer

Contractor crews remove concrete barrier and sidewalk from the 24th Avenue East bridge over
SR 520 in Seattle during a weekend closure of the highway in late November.

With 2015 soon to be history, our contractor crews are working against the clock to open a new State Route 520 westbound off-ramp in Seattle's Montlake neighborhood not long after Father Time flips the calendar. Their aim is to open the new ramp to East Lake Washington Boulevard as close to New Year's Day as possible.

This time-sensitive construction effort is part of a much larger mission – building a new, safer, fixed west approach bridge connecting Seattle's Montlake area with the new SR 520 floating bridge under construction on Lake Washington.

But wait, isn't westbound I-90 going to be closed this weekend also?
Like all big construction projects, building the west approach bridge involves a series of "mini-projects," all planned out and sequenced to occur in succession. The new off-ramp is one of those smaller but critical SR 520 projects.

To complete the ramp, contractor crews first must remove a sidewalk along the edge of the existing 24th Avenue East bridge that crosses over SR 520 between Montlake and the University District. In addition, they must build new piers and extend the overpass northward. As segments of the old ramp disappear next to SR 520 early next year, crews will begin installing more in-water casings and building more support columns for the new west approach bridge. All this work must occur before a seasonal "fish window" closes in April that prohibits major in-water construction on Lake Washington.

The 24th Avenue overpass will carry traffic from the new westbound off-ramp to Lake Washington Boulevard.

Crews began breaking up concrete and removing necessary portions of the overpass during a weekend closure of SR 520 in late November. They plan to finish the needed demolition work during directional closures of SR 520 on the next two Sundays, Dec. 6 and 13. These highway closures are needed to ensure the safety of traffic that would otherwise pass directly underneath the work above.
  • All lanes and ramps of eastbound SR 520 will be closed from 6 a.m. to 10 p.m., Sunday, Dec. 6, between Montlake Boulevard and 92nd Avenue Northeast.
  • On Sunday, Dec. 13, all lanes and ramps of westbound SR 520 will close, if needed, during those same hours from Montlake Boulevard to 92nd Avenue Northeast.
The two weekend lane closures on SR 520 coincide with lane closures on I-90 – but in opposite directions.
  • During this coming weekend when eastbound SR 520 closes on Sunday, westbound I-90 will be reduced to one lane near Bellevue Way Southeast, with traffic rerouted to the express lanes from 11 p.m. Friday, Dec. 4, to 5 a.m. Monday, Dec. 7.
  • The following weekend, with westbound 520 closed on Sunday, eastbound I-90 will be reduced to one lane near Rainier Avenue South, with traffic rerouted to the express lanes from 11 p.m. Friday, Dec. 11, to 5 a.m. Monday, Dec. 14.
The I-90 closures will allow our crews to continue construction of new cross-lake transit and HOV lanes.

So what's next?
Once the new off-ramp opens to traffic, crews will immediately move on to other mission-critical tasks. A key step is removal of the existing westbound SR 520 off-ramp to Lake Washington Boulevard, not far east of the 24th Avenue overpass. This 52-year-old off-ramp, which passes through Seattle's Washington Park Arboretum, must be taken down to make room for the new West Approach Bridge North.  The ramp's removal also will create a more natural, unobstructed environment in the Arboretum.

These and many other individual construction projects, step by calculated step, will lead to the 2017 opening of the new West Approach Bridge North. But in case you haven't heard – cars will be crossing Lake Washington next spring on the new SR 520 floating bridge!