Updated: Dec. 11, 2013
Follow along with WSDOT as we continue to build, tow and assemble pontoons and make progress on the new SR 520 floating bridge on Lake Washington.
Click on the below links to find the content you're interested in:
Diagram showing the construction status and approximate configuration of all 77 pontoons for the new floating bridge. Last updated Dec. 11, 2013. View a printable version
(pdf 200 kb).
Pontoon towing update
- Crews are towing eight supplemental stability pontoons through the Hiram M. Chittenden Locks to Lake Washington this week.
- Pontoon SNE arrived on Lake Washington on Monday, Dec. 9.
- Pontoon SSE arrived on Lake Washington on Tuesday, Dec. 10.
- Pontoon SNW arrived on Lake Washington on Wednesday, Dec. 11.
- Track tugboat Terilyn's movements live online. This tugboat is planned to tow all eight through the Locks.
- The remaining pontoons will arrive throughout the week. Below is the current schedule of arrival dates, which is subject to change based on tow conditions.
- Thursday, Dec. 12 - Pontoon SSW
- Thursday, Dec. 12 - Pontoon RSW
- Friday, Dec. 13 - Pontoon RNW
- Saturday, Dec. 14 - Pontoon RNE
- Saturday, Dec. 14 - Pontoon RSE
Note: While we strive to provide the most up-to-date information possible, pontoon towing details are always subject to change.
Note: Supplemental stability pontoons are the smaller pontoons that will be attached to the larger main longitudinal pontoons that form the spine of the new SR 520 floating bridge on Lake Washington.
West Connection Bridge column construction progress
Diagram showing the current status of West Connection Bridge column construction on Lake Washington. Last updated: Dec. 2, 2013. View a printable version
(pdf 686 kb).
Pontoon transit route
Pontoons for the new floating bridge are being constructed in two different sites in Washington state: Aberdeen and Tacoma. When pontoon construction is complete and they are ready for assembly, they will be brought to Lake Washington through the Hiram M. Chittenden Locks in Ballard.
If you are interested in viewing the pontoons as they make their way to Lake Washington, see our map of suggested viewing locations (pdf 2.5 mb).
Build your own pontoons for the floating bridge
The floating bridge pontoons represent a key milestone in a critical safety project. Using the printable pontoon templates linked below, you can build your own bridge that follows our progress with the construction, transport and final positioning of floating bridge pontoons.
- As we complete the construction of each pontoon and bring them to Lake Washington, we will post new templates here. Each pontoon is labeled according to its location within the final bridge structure.
- For each pontoon, download and print the template file (each pdf is approximately 400 kb), cut along the indicated lines, and then fold your pontoon for final construction.
- We will maintain the links for each pontoon template, so that you can catch up with any you might miss.
Aug. 11, 2012: Pontoon V
Aug. 14, 2012: Pontoon W
Aug. 18, 2012: Pontoon VNW
Aug. 19, 2012: Pontoon VSW
Aug. 22, 2012: Pontoon U
Sep. 22, 2012: Pontoon VNE and Pontoon VSE
Sep. 30, 2012: Pontoon UNE and Pontoon USE
Feb. 2, 2013: Pontoon UNW and Pontoon USW
May 15, 2013: Pontoon T
Jun. 7, 2013: Pontoon A
Jul. 22, 2013: Pontoon TNW
Jul. 23, 2013: Pontoon TSW
Aug. 27, 2013: Pontoon TNE and Pontoon TSE
Aug. 30, 2013: Pontoon S
Oct. 17, 2013: Pontoon BSE
Oct. 20, 2013: Pontoon Q
Oct. 23, 2013: Pontoon R
Oct. 29, 2013: Pontoon BSW
Types of pontoons
The new SR 520 floating bridge will be supported by three types of concrete pontoons:
Longitudinal pontoons (21)
These are the largest pontoons at approximately 360 feet long. They form the backbone of the bridge and support the roadway superstructure.
- Constructed in Aberdeen facility
- Weight: 11,100 tons
Cross pontoons (2)
These mark the ends of the floating bridge section and the transition to the East and West Approach structures.
- Constructed in Aberdeen facility
- Weight: 10,100 - 10,550 tons
Supplemental stability pontoons (54)
These smaller pontoons help stabilize and support the weight of the new floating bridge by joining to larger longitudinal pontoons.
- Constructed in Aberdeen facility (10) and Tacoma facility (44)
- Weight: 2,500 - 2,820 tons