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I-5 Iowa Street Viaduct Replacement and Retaining Structures, Portland, Oregon
The Oregon Department of Transportation (ODOT) Region 1 needed to replace the I-5 viaduct structures in southwest Portland. The project required construction of six new retaining walls to hold the hillside and outboard embankments and support the new bridge abutments. The design was complicated by seven landslide areas located within the project limits. CCI-LT was retained by ODOT to develop geotechnical designs for landslide mitigation, bridge approach retaining walls, bridge foundation design, and tieback retaining walls necessary to gain width. Where subsurface conditions were favorable, cost-effective MSE retaining walls were implemented. Our team worked with ODOT construction to perform special inspections for soldier piles, ground anchors, drilled shafts and all MSE wall elements. 
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View of soldier pile and tieback walls above the roadway and MSE retaining walls being constructed at the south end of the new bridge.
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Project Highlights
The design for the project was performed on a fast-tracked basis to accommodate ODOT’s desired construction window. CCI-LT worked with ODOT’s structural, drainage, and pavement designers to coordinate all PS&E elements developed in parallel. Where geotechnical elements and structural elements of the bridge overlapped, our designers worked with ODOT to develop project-specific design details for walls, moment slabs, and crash barriers. |
Rendering of typical tieback wall used to retain existing landslides. Ground anchors were bonded into basalt underlying the landslide to provide the necessary design life for the structure.
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