DESCRIPTION: ODOT completed widening on I-84 Eastbound to add an auxiliary lane and an exit ramp to I‑205 Northbound. The highway widening was about ¼-mile long and required retaining walls up to ±10 feet tall supporting the toe of a steep, ±30‑foot high slope. The project included the design and construction of cantilever traffic signs, luminaires, and a new off-site water quality treatment facility.
SERVICE: Foundation Engineering provided geotechnical engineering services including site reconnaissance, site access and traffic control permitting, and geotechnical explorations. Foundation Engineering evaluated retaining wall options including gravity, soil nail and soldier pile walls and constructability issues including steep slopes, stability of temporary cuts, boulders, and limited work areas. Design and construction recommendations were provided for foundation support of soldier pile retaining walls including static and seismic lateral earth pressures, and lateral analysis (LPile) to evaluate foundation resistance and stress. Design and construction recommendations were also provided for drilled shaft foundations for cantilever traffic signs and luminaires, and external stability for low height concrete barrier walls. Construction recommendations were also provided for the water quality treatment area access road.