DESCRIPTION: The I-5 at Beltline Interchange Unit 3 (Eugene/Springfield) project is located northeast of downtown Eugene at the I-5 junction with the Beltline Highway. The first two units of this interchange modification project have been completed and Unit 4 is currently in the planning stages.
SERVICE: Foundation Engineering completed geotechnical investigations for the Unit 3 and Unit 4 projects. The geotechnical work was completed to develop design and construction recommendations for the bridge foundations, abutments and wing walls (MUP structures only), embankments, retaining wall, traffic signals, and sign structures. The scope of the geotechnical work included a review of existing information, field exploration, laboratory testing, engineering analyses, and preparation of draft and final reports.
The geotechnical‑related work for Unit 3 supported the design of the following improvements:
- The existing I-5 overcrossing on Beltline Highway was replaced with a two-span bridge. The main geotechnical tasks were to provide design recommendations for the bridge foundations.
- Three new, ±40‑foot long, single-span bridges were constructed in the interchange ramps to carry traffic over the multi-use path (MUP). The main geotechnical task was to provide analysis and design recommendations for the bridge foundations, abutments and wing walls.
- A new, 100-foot long, concrete barrier wall was constructed on C‑Line to provide a low grade separation between C‑Line and E‑Line. The geotechnical tasks included providing design recommendations for the barrier and backslope.
- Three new signal poles were installed at the C-Line and WB Beltline intersection, and one new signal pole was installed at the southwest corner of the intersection of Beltline Hwy and Gateway Street. The geotechnical tasks included providing foundation design recommendations.
- A new cantilevered sign was built at Sta. “C” 850+20, Rt. and a sign bridge was built at Sta. “C” 859+00. The geotechnical tasks included providing foundation design recommendations.
- New embankments were constructed for the bridge approaches and ramps. As part of the geotechnical work, four new embankment profiles were evaluated including one cross‑section along C-Line and F‑Line, one cross‑section along C‑Line (excluding the retaining wall) and one cross‑section along E-Line.