We’ve completed tons of work – many tons of work – since project construction began four years ago. Hundreds of thousands of tons of concrete have gone into building the bridge’s pontoons, anchors, roadway deck, high-rise piers, and support columns. Just one of the 21 longitudinal pontoons for the new bridge weighs 11,000 tons, or as much as 23 Boeing 747s.
|The final deck pour in progress on Oct. 22.|
So pouring the last of this concrete to finish the nearly 2-mile-long roadway surface is a big milestone for the SR 520 Floating Bridge and Landings Project. It’s now physically possible for vehicles to cross the entire length of the floating bridge, from Medina all the way to the existing west approach bridge in Seattle. A lot more work remains, however, before traffic actually switches over from old bridge to new. Here are some of the key tasks we’ll be tackling before we open the new bridge next spring.
|Crews lower the foundation for a noise wall on|
the bridge’s east approach near Medina.
|A barge deposits rock ballast into a pontoon.|
Pontoon ballasting: Ballast rock is being placed inside the pontoons to ensure that the pontoons all sit at the same height in the water. In all, some 70,000 tons of the ballast rock, hauled in by barge, will be added to the pontoons.
|Stormwater drainage pipes are part of the stormwater treatment|
system to capture roadway runoff from the bridge.
Stormwater drainage system installation: Catch basins along the roadway and piping that runs along the underside of the roadway deck will capture roadway runoff, lessening the environmental impact of the bridge on Lake Washington.
|Outside view of the LEED Silver certified bridge|
|Some of the 300 miles of electrical wire that will|
be used on the bridge – enough wire to stretch
from Seattle to Idaho.
Bridge maintenance facility construction: A new bridge-maintenance facility is under construction below the East Approach of the bridge, on the Medina shoreline. This facility will house maintenance and repair equipment for the bridge and allow crews to quickly respond to any bridge-maintenance needs that arise.
Connecting bridge safety and management systems: These are the invisible hands that keep traffic flowing, including fire-safety systems, bridge sensors, and electronic traffic signs, like those showing variable speed limits.
|A rendering of the bicycle/pedestrian path on the bridge,|
including one of the decorative sentinels that mark the
ends of the bridge.
Completion of architectural elements: Crews will install bridge lighting and decorative “sentinels” that mark the east and west ends of the longest floating bridge in the world. On the bridge’s 14-foot-wide bicycle and pedestrian path, we’ll finish installing rest areas/viewpoints, or “belvederes,” as well as nearly 8,500 feet of railing.
You can follow the progress of our final bridge-building activities as we count down to project completion. View this bridge-commissioning graphic on our website – and start to get excited about crossing the world’s longest floating highway in spring 2016!