Allegheny Mountain Realignment - Overview

The project is located approximately 13 miles east of the Somerset Interchange (Exit 110) and 23 miles west of the Bedford Interchange (Exit 146) on the Pennsylvania Turnpike. It spans the townships of Allegheny and Stonycreek in Somerset County. Please refer to the location map found on this website.

The purpose of the project is to:

• Improve safety and decrease accidents for motorists traveling through this section of the Turnpike.
• Relieve traffic congestion and improve the level of service.
• Improve system linkage and continuity for hazardous material carriers, which are not permitted in the tunnel.

Five needs are established for this project:

1. Transportation Demand: The current and future transportation demands on the tunnel and its approaches result in an unacceptable Level of Service (LOS) and traffic congestion.
2. Existing Geometric Constraints: Some geometric features of the tunnel and its approaches do not meet current highway design standards with respect to lane width, termination of truck climbing lane, horizontal curvature, and sight distance.
3. Accident Rates: The accident rate for the tunnel and its approaches is higher than the entire Turnpike system and PennDOT statewide rates.
4. Tunnel Conditions: Both the eastbound and westbound tunnels are in need of major rehabilitation.
5. System Linkage and Continuity: Certain hazardous materials are not permitted through the Allegheny Tunnel. Travel on the Turnpike is currently disrupted because of diversion of hazmat haulers to local roads.

The preliminary design phase is expected to continue into Q1 of 2029. 

During this phase, the Project Team will refine the new roadway alignment, confirm environmental impacts, and work to minimize right of way impacts. Property owners adjacent to the Turnpike will receive formal notification letters regarding upcoming fieldwork in the project area. This includes surveyors affirming property lines, geotechnical engineers conducting more detailed soil testing, and environmental specialists conducting more detailed studies on wetlands, wildlife, farmlands, and historic resources in the area and how to mitigate impacts.

Team members may need access to property outside of the PA Turnpike's right of way to conduct this field research accurately, which is why you or your neighbors may receive a Notice of Intent to Enter letter. The preliminary design phase will conclude with a public meeting where the public can examine the proposed design plans and the additional right-of-way required by the project. The public will have the opportunity to provide comments, which will be recorded and considered during the final design phase of the project. 

Once preliminary engineering is completed in 2028, environmental impacts on the new alternative will be shared.

The gray cut alternative was identified because it best meets the project needs and balances environmental, engineering, operational, cost, and safety considerations. Numerous alignments were evaluated and presented to resource agencies, elected officials, and the public. The gray cut alternative was chosen as a result of environmental agency input during the study phase completed in 2021.