Just as the Montlake Lid project is laying down its final layers of landscaping bark, the Washington Department of Transportation says construction began this week for SR-520’s Roanoke Lid and Portage Bay Bridge project:
Beginning the week of Nov. 4, crews will start piledriving in Portage Bay to build the temporary work trestle and future westbound Portage Bay bridge. A work trestle is essentially a temporary platform that crews need to build so they can construct the permanent bridge. This will be the first of six piledriving “seasons” allowed on this project. Each season lasts from September through April. This first season – from November 2024 through April 2025 – will be the most significant season of impact piledriving work. The following seasons will have less piledriving – and some seasons may not drive piles at all.
The bridge work is a long process. The state says crews will use two methods to install or “drive” the piles. The first method uses a vibratory hammer to “vibrate” the piles into the bottom of the bay. The second method uses an impact hammer to strike the piles like a hammer into the base of the bay: Continue reading