I-81 Improvement Strategy

Central Pennsylvania

In 2018, the Pennsylvania Department of Transportation (PennDOT) asked Michael Baker to review and update a plan, originally completed in 2005, for widening and reconstructing a 100-mile corridor of Interstate 81 (I-81) in central Pennsylvania. The plan concentrated primarily on adding a third lane to the highway to alleviate congestion — a significant issue since I-81 is a critical artery and a primary route to and from the state capital of Harrisburg. Michael Baker executed the assignment, but when the findings were presented to PennDOT and major stakeholders, the group realized that the $2.9 billion estimated price tag made corridor-long widening untenable.

With the high cost of the widening option, the three Metropolitan Planning Organizations along the corridor – Franklin County, Harrisburg Area and Lebanon County – shifted the focus to investing in more locally centered projects that would serve to address immediate needs, such as easing traffic congestion, improving safety and enhancing development and preservation.

As project manager, Michael Baker studied all available traffic data and gathered feedback from interest groups, stakeholders and travelers from across the corridor. This generated significant public involvement, including more than 3,500 survey responses, 2,700 comments and more than 700 in public meeting attendance. This feedback was used to identify the needs, priorities and conceptual improvements. The Michael Baker team also considered data from multiple sources on projected residential, commercial and industrial development, how those phenomena might affect local I-81 traffic and ways to accommodate this projected growth. The collective resulting information was used to develop a single document: The Playbook to Set Priorities.

The playbook includes conceptual plans for 36 projects — complete with projected costs — all described and ranked by priority on an easily accessible master project website. The playbook serves as a guide for stakeholders as they set priorities and funding for future projects as resources become available through the Statewide Transportation Improvement Program (STIP). Shortly after its adoption, the Harrisburg Area Transportation Study funded preliminary engineering for three of the projects, validating what an important resource the playbook already has become.


“The [playbook] projects differ in scope and objective, but they feature several common themes, including a commitment to safety, accommodations for growth in population and traffic volume and compatibility with sustainable development.”

- Project Manager

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