Tuesday, June 28, 2011

Work is progressing on the new bridge on SR 529 at the Ebey Slough

by guest blogger Bronlea Mishler

As you drive through Marysville on I-5, it might be easy to overlook the little steel bridge just to the east, spanning the Ebey Slough on State Route 529. But if you’re stuck in seemingly never-ending freeway traffic, that little bridge can become a driver’s best friend. Built in 1925, the swing-span bridge across the Ebey Slough gives local drivers the option to avoid I-5 congestion as they travel between Everett and Marysville.

Back in its heyday, however, the span was one of the few options for crossing the Ebey Slough. At the time, the bridge was the pinnacle of then-modern technology. It could pivot open at its center to allow tall boats to pass, then swing closed to allow traffic across. One 11-foot-wide lane in each direction gave drivers ample room, and a three-foot sidewalk gave bicyclists and pedestrians space to cross, too. 

Fast-forward 86 years, and that once-modern bridge now seems narrow – unsuited for today’s wider vehicles – with not enough room for pedestrians and cyclists to pass. And frequent openings for marine vessels can put a serious hitch in drivers’ daily commutes.

Fortunately, a solution is on the way. Last year, crews began work on a replacement Ebey Slough Bridge – this time taller, wider, and built out of sturdy steel girders with a concrete roadway. Standing 13 feet taller than the old bridge, the new span won’t need to open for marine traffic. And with two 12-foot driving lanes in each direction, plus two six-foot sidewalks and two five-foot bike lanes, there’s plenty of room for all types of commuters.

This month marks a major milestone for construction crews as they begin setting 49 girders, each weighing in at approximately 31 tons. It’s more visible work for drivers, too. Most of the work completed since last year has been fairly innocuous: Crews have built temporary work platforms above the slough, drilled deep holes for steel and concrete pilings, and prepared the support structure for the steel girders. Now that the girders are in place, the new bridge is really beginning to take shape – literally. For the first time, the new 680-foot span is beginning to look like a bridge, not just a forest of concrete pillars.

Placing each of the girders – which stand seven feet tall and range in length from 100 to 135 feet – is a time-consuming process. Two cranes pluck a girder from the work platform, carefully guide it into position, and then gently swing it into place atop the concrete pilings. The crews typically set 3 girders per day, and expect to wrap up placement of all the girders by the end of June.

By April 2012, drivers who have patiently (or not-so-patiently) been watching the new bridge take shape will finally get a chance to drive on the span. Crews plan to open the bridge to northbound traffic in April; southbound traffic will have to wait to use the new span until August, as crews wrap up work in those lanes. Once all traffic is on the new bridge, crews will demolish the old steel span.