With a mighty push, crews have begun a six-week process to propel three steel bridge girders across the Snohomish River near Monroe.
The girders form the backbone of a new bridge the Washington State Department of Transportation (WSDOT) is building as part of a project to widen State Rte. 522 from two lanes to four. The work requires nightly single-lane closures.
Crews must extend the girders 600 ft over the water and another 325 ft over land. Since there is not enough room to place cranes along the riverbank or on a work barge, WSDOT is using a technique known as launching to push the girders into place.
“Launching the girders instead of lifting and setting them in place with a crane means we won’t need to completely close the highway or the river channel,” said WSDOT Project Engineer Janice Fahning. “Drivers will see significant progress but basically the same travel conditions they’ve experienced throughout construction.”
Due to the limited space in the construction zone, each of the three girders will be divided into six sections averaging about 150 ft long. Crews launched a portion of the first section July 14. After making some adjustments, crews finished pushing out the first section over the river July 27. Each week, new girder sections will be added until the entire assembly is complete. The three girders have a combined weight of more than 2 million lb, each moving no faster toward its position than an inch per second. Once complete, the bridge will be more than 1,700 ft long.
The $159.7 million S.R. 522 widening project is one of the final projects in Snohomish County funded by the 2003 gas tax. Crews are adding one lane in each direction of S.R. 522 between the Snohomish River and U.S. 2 in Monroe. The widening project includes four new bridges, a roundabout near 164th Street Southeast, a noise wall near 171st Avenue Southeast and a median barrier to separate eastbound and westbound traffic.
