Salters Road and S-326 Improvements Program

S&ME provided geotechnical services for the Salters Road and S-326 Improvements project, a significant upgrade to an important transportation connection over Interstate 85 and Clemson University International Center for Automotive Research and the Millennium Campus areas, and the Verdae Boulevard corridor. S&ME provided preliminary and final design phase subsurface explorations, foundation design, and engineering support during construction. The project consisted of widening, partial realignment, and improvements to a total of approximately 1.363 miles of roadway, along with intersection improvements, and replacement of the Road S-326 Bridge over I-85. The project site is in Greenville County, South Carolina.

A new bridge was constructed along the realigned portion of Road S-326.  The approximate dimensions of the bridge are 204 feet in length and 91 feet in width, with 20-foot tall MSE abutment walls.  The bridge has two 102-foot long spans with pre-stressed concrete beams, spanning the maximum future I-85 build out.  The structure is supported at integral End Bents 1 and 3 with driven HP14x73 pile foundations, and at Interior Bent 2 with five drilled shaft foundations socketed into rock.  MSE Walls are constructed at the bridge abutments as well as along a section of roadway widening through the Preserve at Verdae Golf Course, to limit the lateral extension of embankments over existing culverts for Laurel Creek and a golf cart tunnel.

Field exploration services included 11 soil test borings for the bridge foundations and associated abutment walls, and 46 borings for the roadway sections and associated MSE retaining walls, culverts, and drainage structures. Rock coring was performed upon encountering refusal conditions in the bridge borings.  The existing asphalt pavements were cored and measured to help assess portions of pavement section that could remain in-place to help support new pavement sections.  Shear wave velocities were measured using MASW and MAM methods, for use in seismic design.  Laboratory testing on SPT, bulk, and UD samples included index tests, Proctor, CBR, organic content, and unconfined rock compression.

Engineering design services included preliminary and final design phase recommendations for deep foundations (driven piles and drilled shafts), including point-of-fixity and LRFD design methodology.  S&ME performed external design analysis and global stability analysis for the MSEW Walls for both roadway and bridge abutment walls, and provided recommendations for grading the encountered soils and pavement support characteristics.  In addition, engineering support was provided for deep foundation modifications during construction, along with MSE plans/calculations review.

Planning and engineering services for the project was led by TranSystems in association with HDR, Inc. and S&ME. The American Council of Engineering Companies South Carolina Chapter honored the project in 2019 as the State Finalist and ACEC Finalist in their annual Engineering Excellence Awards competition.