Inside/Out Newsletter
Engineering Excellence
240th Street SE/North Creek Bridge Replacement
The American Council of Engineering Companies awarded the 240th Street SE over North Creek Bridge replacement project the Best in State Silver Award for Meeting and/ or Exceeding Owner’s Expectations to the City of Bothell, Washington. BergerABAM led the multidisciplinary team for this significant bridge replacement project. In 2011, the City had planned to replace the original, structurally deficient bridge— originally built in 1962—spanning the North Creek. However, an inspection during the design process revealed that advanced deterioration of the timber piles and several flooding events had compromised the structure’s integrity. As a result, vehicles could not safely drive over the bridge. The City was forced to immediately close the bridge to the thousands of daily commuters who traveled across North Creek Bridge, months sooner than planned. Immediate action to design, build, and open a new bridge was needed after this emergency closure. BergerABAM’s design team worked with the City to develop a new design strategy to fast track the design, permitting, and construction to be completed a year ahead of the original schedule. In addition, the project had to be worked on a schedule to maximize work during the limited summer 2011 fish window. Leading a team of engineers, scientists, and technicians, BergerABAM provided planning, engineering, environmental permitting, geotechnical engineering, hydraulic analysis, surveying, rightof-way acquisition, construction engineering, public involvement, and utility coordination. By 2012, BergerABAM had completed the bridge—not only on time, but the team also designed the bridge with enough clearance for debris to flow underneath the bridge during a 100-year flood without having to significantly increase the elevation of the approach grades. The sheet pile wall system with dead-man anchor tiebacks employed in this design
The new vehicle and trail bridges that replaced deteriorating and unsafe structures were fast-tracked and completed one year ahead of schedule.
allowed construction near the stream, while outside of the in-water fish work time frame. This cost-effective design minimized costs and met current Federal Emergency Management Act flood-level requirements. Because of similar foundation concerns as the vehicular bridge, the North Trail Bridge (next to the vehicular bridge) that connects the regional North Creek Trail was replaced with a 74-foot-long, prefabricated bridge with a longer span to minimize hydraulic and environmental impacts. During the heavy rains in November and December 2012, the bridge performed as expected with significant improvements. Though the BergerABAM team did not expect all flooding issues would be eliminated, the City inspector reported that approximately 1 inch of clearance under the bridge was nevertheless achieved with minimal bridge closure time, during one of the heaviest rainfalls of the season.
Editors / Writers Jana Roy Dee Young Karen Harbaugh Chris Cornell Diann Scherer Design and Production Jana Roy
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