US 11/15 Rock Slope Safety Improvement, PA
AEG, a SOCOTEC Company served as Prime Consultant for the US 11/15 Rock Slope Safety Improvement Project in Cumberland County, PA, delivering geologic investigation, rockfall analysis, slope protection design, traffic planning, and construction consultation.
Key Information
Project: US 11/15 Rock Slope Safety Improvement Project
Client: PennDOT District 8-0
Location: Cumberland County, PA
Award: ASHE Northeast Region Project of the Year
Services Provided: Geophysical and Construction inspections
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The Challenge
Managing Rockfall Risk Across Two Distinct Sites
The US 11/15 Rock Slope Safety Improvement Project addressed falling-rock hazards along an important transportation corridor in central Pennsylvania.
The work covered two separate areas located approximately seven miles apart, each with different physical and operational conditions.
The Marysville Section, located just north of the US 11/15 and Interstate 81 interchange in East Pennsboro Township, contained four primary rock cuts. The Duncannon Section, in Penn Township approximately 0.8 miles south of the Borough of Duncannon, included one significant rock cut.
Because the slopes differed in geometry and geologic characteristics, the project required a site-specific understanding of potential failure mechanisms rather than a single uniform approach.
Traffic impacts also varied between the two locations. The team needed to consider how roadway work could be performed while limiting disruption, with particular attention to the Marysville detour and coordination with emergency management services.
The Solution
Site-Specific Geotechnical Engineering and Rockfall Mitigation
As Prime Consultant under a project-specific open-end contract, AEG, a SOCOTEC Company supported the project from preliminary investigation through final design and construction consultation.
The team performed detailed geologic mapping and analyzed historical aerial photography to build a clear understanding of slope conditions.
AEG then used the Colorado Rockfall Simulation Program (CRSP) and RockPack III to evaluate rockfall behavior and support engineering decisions.
The technical assessment included:
- Identification of potential failure mechanisms
- Evaluation of rock shear strength
- Evaluation of rock compressive strength
- Preparation of digital documentation for design development
Using these findings, AEG developed tailored slope protection systems for the individual project locations.
To address roadway operations, the team evaluated widening and closure alternatives and coordinated with state, county, and municipal emergency management services where required.
During construction, AEG provided expedited reviews of contractor submittals and responded quickly to field conditions to support continued progress.
As Prime Consultant under a project-specific open-end contract, AEG, a SOCOTEC Company supported the project from preliminary investigation through final design and construction consultation.
The team performed detailed geologic mapping and analyzed historical aerial photography to build a clear understanding of slope conditions.
AEG then used the Colorado Rockfall Simulation Program (CRSP) and RockPack III to evaluate rockfall behavior and support engineering decisions.
The technical assessment included:
- Identification of potential failure mechanisms
- Evaluation of rock shear strength
- Evaluation of rock compressive strength
- Preparation of digital documentation for design development
Using these findings, AEG developed tailored slope protection systems for the individual project locations.
To address roadway operations, the team evaluated widening and closure alternatives and coordinated with state, county, and municipal emergency management services where required.
During construction, AEG provided expedited reviews of contractor submittals and responded quickly to field conditions to support continued progress.
The Results
Safer Slopes and an Earlier Roadway Reopening
The project delivered targeted improvements intended to reduce falling-rock hazards and improve long-term slope stability along US 11/15.
Construction support and timely decision-making helped keep the work moving, contributing to the contractor reopening the roadway nearly one month ahead of schedule.
The project also demonstrated the value of adapting slope improvements to the specific conditions of each location while accounting for roadway operations and emergency access.
In 2018, the project received the ASHE Northeast Region Project of the Year award, recognizing the technical and collaborative effort behind its delivery.
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