Only three Rall-bascule highway bridges exist in the U.S. today, the largest easily Portland’s Broadway Bridge. But at over 100 years old, the four giant bull wheels that help manage the lifting of the draw spans have started to deform. Multnomah County, the bridge owner, sits poised to get a contractor to fix the problem, a $10 million project they hope to accomplish in 2015.
The 70-ft-wide and 1,613-ft-long bridge, with a 278-ft double-leaf Rall bascule main channel draw span, was built in 1912 and still opens about 25 times per month to allow ship passage along the heavily bridge Willamette River, taking 20 minutes or longer with the Rall style.
Every time Broadway opens the double-leaf bascule—French for seesaw—counterweights located above the bridge’s deck balance the weight of the deck.
Each leaf and counterweight roll back and forth on the wheels, designed by Theodore Rall, until the 2,000-ton decks—Broadway is the seventh longest bascule bridge in the world—open.
But those Rall wheels have started to crack and deform, requiring Multnomah County to look at replacing them in November 2015, a process they must start now to ensure they find the best contractor for such a specialized and complicated repair.
The county really wants to get this repair right, as they have so far with the Sellwood Bridge move farther south, even as the Morrison Bridge project, just south of Broadway, went array and requires a near-complete redo of the deck.
Multnomah County will get their chance, though, by fixing up a 100-year-old Portland icon.
Tim Newcomb is Engineering News-Record’s Pacific Northwest contributor. He also writes for Popular Mechanics, Sports Illustrated and more. You can follow him on Twitter at @tdnewcomb or visit his website here.