Pennsylvania Turnpike Southern Beltway, Southwestern Pennsylvania

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Overview: Since 2013, GeoStructures has teamed with the Mechanicsburg, Pennsylvania office of Stantec to provide geotechnical design services for a new 3-mile section of the $700-million, 13-mile tollway of the Pennsylvania Turnpike Southern Beltway. Construction for Section 55B of the Southern Beltway began in January of 2017.

Major components of Section 55B included a 5-span bridge (170-ft high), cuts and fills (160-ft high), an MSE wall, a 1.5:1 steepened rock embankment, 2 culverts, 1 mile of side road improvements & relocations, and 15 stormwater basins. The field exploration portion of this project involved 158 test borings (maximum depth of 200 ft), inclinometers, stormwater infiltration tests, and pavement cores with DCP testing along existing side roads. The following research and design measures were also implemented during the project:


  • Research of historical coal & strip mine records
  • Interpretation of coal mine boring data to develop composite foundation for the 5-span bridge
  • Research of ancient landslides and detailed risk assessment of 14 closed-form landslide features mapped by USGS
  • Use of LIDAR data and exploration data from test borings, inclinometers, and residual direct shear testing to identify 5 high-risk landslides containing colluvial soils, active shear zones with friction angles as low as 10°, and artesian groundwater conditions
  • Design of a drainage blanket and rock buttress mitigation plan to stabilize landslides as large as 75,000 CY below the main line, as well as along several high-risk basin side cuts

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Percolation and Permeability In-Situ Testing 

Drilling Services and Subsurface Investigations

Foundation Investigation and Design

Highway and Bridge Geotechniques

Support of Excavation and Underpinning

Soil-Structure Interaction Analysis and Modeling

Soil Dynamics & Site-Specific Response Spectra

Vibration Monitoring and Analyses

Forensic Evaluations

Slope and Retaining Wall Evaluation and Design

Lime and Cement Stabilization

Mine Subsidence Analysis and Remediation

Sinkhole Evaluation and Remediation

Soil Improvement Techniques

Dam Analysis and Rehabilitation

Environmental Services

Landfills, Ponds, and Lagoons

Pavement Design and Rehabilitation

Construction Inspection and Materials Testing

Geotechnical Laboratory Testing

Concrete and Cement Testing

Petrographic Analysis

Instrumentation and Special Testing

Asphalt Testing

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3-D Dynamic Finite Element Analysis



Institutional & Educational


Industrial, Pharmaceutical, & Gene Therapy

Landfill Expansion Design


Research & Forensics


Water & Wastewater

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