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SR 520 Pontoon and Floating Bridge - Progress Update

Latest updates

Jan, 31, 2013 - Read our latest message to the Washington State Legislature and KOMO TV

WSDOT recently received several questions from KOMO TV and conducted a site tour at the Aberdeen casting facility. We want you to have all of the information we've shared with KOMO, so we posted our latest response (pdf 52 kb). 

We've also posted our email to members of the Washington State Legislature (pdf 1.13 mb) alerting them to this latest round of correspondence. 

Finally, we've posted an overview of the SR 520 budget (pdf 328 kb), including a detailed explanation of SR 520 program funding sources and their uses.

New photos on Flickr: continued progress in Aberdeen



WSDOT crews continue to make progress on the second cycle of pontoons under way in Aberdeen.

Check out our Flickr album to see the latest photos both inside and outside of the latest pontoons.


Previous updates

Jan. 28, 2013 - Second Tacoma pontoon float-out under way





On Jan. 28, 2013, crews began activites to prepare the second float-out of supplemental pontoons built in the Tacoma casting basin.

U.S. Rep. Derek Kilmer joined Paula Hammond and other regional leaders to celebrate the continued construction and the positive effect SR 520 work has on Tacoma, Pierce County and Washington state.

Floating out all six pontoons from this cycle will take multiple days. Check out our Pontoon Tracking page for the latest float-out details and how you can pontoon towing progress to Seattle in real-time.

View more photos on our Flickr gallery or read more about the Monday event.


Dec. 21, 2012 - Experts confirm rebar provides pontoon structural capacity
Expert Review Panel adds new members with additional expertise

An analysis using computer modeling, onsite inspections and engineering calculations has determined that rebar in the corner joints in three completed pontoons for the SR 520 bridge provides the required structural capacity. WSDOT also announced the addition of two new members to the Expert Review Panel. More...

Dec. 14, 2012 - Continued progress on SR 520 east approach bridge piers
Quality assurance update: One column to be replaced at contractor direction

Upcoming work on piers and columns for the new State Route 520 bridge will involve excavation in the lakebed inside a protective steel curtain known as a cofferdam. Crews are also removing and replacing one of 10 concrete columns atop a pontoon where the concrete pour failed to meet quality specifications. More...


Dec. 4, 2012 - View photos of underwater diver inspections

An SR 520 underwater diver



As the new SR 520 floating bridge takes shape, crews continue thorough inspections of the concrete pontoons that will serve as the floating foundation. View recent underwater inspection photos on our Flickr set.

Nov. 19, 2012 - Pontoon RFP quality requirements, additional correspondence between WSDOT and KOMO posted

WSDOT recently received questions from KOMO regarding quality assurance and other topics.

View our response to KOMO (pdf 305 kb), which included the pontoon project RFP quality control requirements (pdf 2 mb).

Nov. 15, 2012 - Pontoon Quality Management Plan, additional correspondence between WSDOT and KOMO posted

WSDOT recently received questions from KOMO that cited an anonymous source regarding the quality control process. Questions were raised about such things as rebar being placed without proper clearances, concrete pours done in rain, and other topics.

View our response to KOMO (pdf 47 kb), which included the Quality Management Plan (pdf 10 mb) developed by pontoon contractor Kiewit-General.

Nov. 14, 2012 - Superstructure milestone; media invited to tour pontoons on Lake Washington

We recently completed the first concrete superstructure on top of Pontoon W at the east end of Lake Washington to support the new SR 520 floating bridge deck.

Five columns under construction on Pontoon W

The five columns are approximately 55 feet tall and 4 feet in diameter.

We also invited media to tour the exterior of Pontoon W and the interior of Pontoon V.

Media guest on the existing 520 bridge

More photos are on Flickr.


Nov. 5, 2012 - Project overview video

Click to watch a presentation on the floating bridge and pontoon projects on YouTube

Streaming video link (WMV)


WSDOT and KOMO email correspondence

KOMO-TV recently interviewed Secretary of Transportation Paula Hammond, which you can see below. In addition, we've also provided several detailed responses to questions received from KOMO.

We've posted their questions and our answers so you can have all of the information we've shared with KOMO.

Link: WSDOT and KOMO email exchange (pdf 510 kb)

Pontoon inspection videos

We want you to be able to see all of our inspection videos of the new SR 520 bridge pontoons. This summer, our pontoon inspection crews recorded and cataloged over 45 hours of pontoon inspection footage so we could track issues that needed repairs.

We've posted their footage -- completely unedited -- for you to view. A word of warning: many are huge files (some over 1 GB large!), so they may take a while to download.

Link: Pontoon inspection videos page

Paula Hammond and KOMO TV - the full 25-minute interview

Watch the full interview between Secretary Hammond and KOMO-TV on YouTube

Streaming video link (WMV)

Have additional questions? Let us know

Email: SR520Bridge@wsdot.wa.gov
Phone: 206-770-3500