An anonymous reader wants to know: “Behind the Vancouver Marine Park boat launch, there is a large bridge under construction. What is it? How will it be moved when it’s done?”
The Marine Park boat launch ramp is tucked into a corner of the Columbia Business Center between state Highway 14 and the Columbia River, and if you’ve ventured down there in recent weeks (while observing proper social distancing measures, of course), chances are you’ve noticed the new bridge taking shape on the other side of the fence by the parking lot.
It’s pretty hard to miss; the arching steel truss structure is significantly taller than all of the surrounding buildings. It’s sitting in a fabrication yard operated by industrial manufacturing company Vigor.
So, what is it?
It’s a railroad bridge. Specifically, it’s a replacement for a century-old bridge over Drano Lake in Skamania County, which serves the main BNSF Railway line that runs east from Vancouver along the north side of the Columbia River.
There’s more to say, but first, a quick historical detour: You might be wondering why the lake shares its name with a highly corrosive household cleaning agent.
It turns out it’s a coincidence; according to the Tacoma Public Library’s Washington Place Names database, the lake apparently takes its name from William Drano, a 19th century homesteader who predated the invention of the clog-busting goop by several decades.
Anyway, the current Drano Lake bridge (or to use its less-glamorous official title: Bridge 66.4) dates to 1907 and has exceeded its design service life, according to a 2016 Notice of Intent that BNSF filed with Skamania County.
The replacement project is expected to cost about $15 million, according to BNSF spokesman Gus Melonas. It’s one of several bridges along the Columbia River Gorge line that have been on BNSF’s replacement checklist in recent years, as part of a broader push to upgrade its statewide rail network.
The rail company replaced a similar bridge last year near Home Valley, about seven miles west of Drano Lake, and in 2017 it wrapped up construction on a replacement for the Washougal River railroad bridge in Camas after more than two years of work.
The new Drano Lake bridge will consist of a roughly 360-foot central steel through-truss span – that’s the part you can see from the boat ramp in Vancouver – and two short precast concrete approach spans, one on either side, for a total bridge length of approximately 440 feet, according to Melonas.
Construction is already underway at the Drano Lake site, with crews driving pilings for the two main piers that will support the truss. Once the piers are ready, the finished truss will be transferred to a barge and floated up the Columbia River to the job site. That’s planned for August, Melonas said.
A temporary support structure will be built ahead of time next to the bridge, allowing crews to quickly slide the old truss out and swap the new one in to take its place. The goal is to minimize the disruption time for the rail line, which carries roughly 40 trains per day including both BNSF freight and two trains on Amtrak’s Empire Builder line.
The Home Valley bridge has a similar design and was installed using the same method last summer, Melonas said, with trains rerouted during the closure. In that case, the main rail line was back in service in 36 hours, and Melonas said BNSF is targeting a similar schedule this time around.
Most rail bridges are built in place, he said – only about four or five BNSF bridges in the past decade have been built using the float-in method. But the Home Valley and Drano Lake bridges both faced topographical constraints that made it easier to build the bridge remotely.
“This is an extremely rare engineering project,” he said.