The four-mile section of the two-lane Coos County road is adjacent to the South Fork of the Coquille River. With funding from the Federal Highway Administration, The project consisted of the replacement of three major tributary stream crossing structures, mitigation of two landslide areas, earthwork associated with roadway realignment, and new and overlay asphalt pavement. Replacement of two existing box culverts and one bridge included a new 80-foot-long, single-span bridge and two multi-plate pipe culverts with spans of 15 to 20 feet and lengths of 30 to 70 feet. GRI completed geologic mapping; completed borings in soil and rock; performed laboratory testing; and installed a slope inclinometer casing, vibrating-wire piezometer, and a data logger, and monitored. GRI provided recommendations for foundation support for the new bridge and culverts including criteria for deep and shallow foundations, retaining walls, earthwork, and site preparation including cut and fill slopes and structural fill, site drainage and erosion control, and alternatives for mitigation of slope instability.

Location: Curry County, Oregon

Owner: ODOT; Funded by Federal Highway Administration

Market Sector: Federal, Transportation

Services: Geotechnical Engineering, Geologic Hazards, Seismic Engineering