Seattle's on one side of Lake Washington, with Bellevue and Redmond on the other side, right? People and businesses on both sides. The lake's too wide for suspension bridges or deep-bore tunnels, so the solution is a pair of floating bridges. And one of them, having stood (or floated) for 50 years now has to be replaced.
It took a gajillion years to bring the Interstate 90 bridge between Mercer Island and Seattle to federal highway standards, and all we have to say is, Thank God the job's done, and not just because the old floating bridge actually sank. Meantime, WSDOT, the state highway department, is in the process of rebuilding the ancient 520 bridge, a $4.6 billion project, and they still haven't decided how to connect the new bridge to shore on the Seattle side.
The new pontoons, 77 of them, are arriving one by one at Shilshole Bay from shipyards in Tacoma and Aberdeen. They weigh 11,000 tons, and measure 360 feet long, 75 feet wide and 30 feet high. They just barely fit through the Hiram Chittenden Locks, then get pushed through the Ship Canal, Lake Union, the Montlake Cut and Portage Bay out to the construction site on the lake.
(Don't laugh: when Metro built the bus tunnel under Third Avenue in Seattle, they didn't get the rails right and had to close it for two years to "retrofit" the tunnel for light rail.)
Even though it's going to be a toll road (and a stiff toll at that), the state is $2 billion short, without any idea of what the western interchange at Montlake will look like. The city council and Metro still don't know how they're going to hook into the new traffic ramps.
Part of the problem with the Montlake bridge is that straddles the Montlake Cut, the shipping lane between Lake Washington and Lake Union. It has to be raised to allow tall-masted vessels to pass. When that happens, traffic stops dead. Not just the folks who want to cross to or from the University District, but folks who want to get on and off the 520 roadway as well. Will WSDOT spend $2 billion to create ramps that bypass the old bascule?
Metro is in on this. Half a dozen bus lines use 520 and would use the Montlake Interchange. Another four cross the Montlake Bridge on north-south routes.
And did we mention that the Link Light Rail line's University Station is already being built on the Husky Stadium side of the bridge? At least the train itself will travel through a tunnel so riders won't be able to use the classic Seattle excuse, "Sorry I'm late, the bridge was up."
In the meantime, what to do with the pontoons from the old 520 bridge? The're too big to sink into the lake, too unwieldy to tow out to sea and scuttle. And there are 33 sections, each weighing 10 million pounds and as long as a football field. WSU grad student Sara Strouse came up with a contest for her architecture thesis, "Rethink ReUse," and drew 73 submissions from 20 countries. The winning entry, by Seattle residents David Dahl and Nicole Lew, was called the "South Park Food Bridge." It would use the pontoons to reclaim the Duwamish waterfront in South Park. One set of pontoons would form parks with urban gardens and a boardwalk. The other set would be more porous and devoted to wetland habitats above and below the water line.
Note: this post first appeared on Curbed.com