Erdman Anthony is designing improvements along a 73-mile stretch of PA Route 120 to correct slope failures at various locations that have mountainous terrain. Slope stabilization is being analyzed and remediated using a variety of methods, including soil nails and retaining walls.
Erdman Anthony also is managing the geotechnical engineering provided by a subconsultant, and using recommendations to develop slope stabilization and structural, roadway, and drainage design as needed. The design at some locations is being expedited due to the emergency nature of the existing conditions.
The final design for one such project was completed within a two-month time frame, and others are being completed using design-build methods.
The narrow corridor and terrain have led to innovative techniques, such as top-down construction involving soil nail installation from the existing roadway above the slope. Borehole cameras have been used to identify existing soil conditions.
Construction methods such as modifications to grout, soil nail socks, and modified soil nail installation patterns have also been used in some areas to mitigate existing geologic conditions.