DESCRIPTION: The Delta Ponds Pedestrian Bridge was constructed in 2010, crossing over Delta Highway and connecting the paths from Goodpasture Island Road to Robin Hood Avenue. The bridge is ±760-foot long with a ±290‑foot long, two‑span, cable‑stay main structure and 15 approach spans. The bridge is supported on 4‑foot to 8-foot diameter drilled shaft foundations. Mechanical stabilized earth (MSE) walls were constructed at the ends of the bridge to retain the approach fill and limit encroachment on the adjacent properties.
SERVICE: Foundation Engineering completed the geotechnical investigation for the project. The investigation included six exploratory borings extending to a maximum depth of 80 feet, laboratory testing, engineering analysis and development of recommendations for site preparation and the design of bridge foundations and approach embankments retained by MSE walls. The bridge foundations extend into weathered silty sandstone of the Eugene Formation. A key challenge for foundation design was evaluating appropriate strengths for the variable bedrock. During construction, we provided review of the drilled shaft and MSE wall submittals and periodic on-site observations during foundation construction.