American Society of Highway Engineers (ASHE) Southwest Penn Section
The Southern Beltway Project (U.S. 22 to I-79) is a significant element of a major transportation improvement plan for the southwestern Pennsylvania region being administered through the Pennsylvania Turnpike Commission (PTC). A project of massive proportions, ms has been working alongside PTC and many other consultants on this project for more than 10 years. This project creates a toll road system around Pittsburgh to the south and west, connecting the Pittsburgh International Airport with the Monongahela Valley and West Virginia to the south.
ms consultants provided preliminary design and comprehensive environmental documentation for a 116-square-mile project study area for the development of a new toll road expressway, which was to be a four-lane limited access highway with an anticipated four interchanges.
Preliminary environmental considerations included:
Five new toll road alternatives were evaluated by ms consultants in an Environmental Impact Statement. Evaluation was based upon the alternative’s ability to meet the project need, environmental and socioeconomic impacts, as well as sound engineering practices. Based on this analysis, ms consultants was able to eliminate two alternatives from further investigation. The report documents the findings of these investigations, preferred alternatives, as well as the public and agency involvement. The report was submitted and approved by the Federal Highway Administration.
Key environmental considerations in the development of the evaluation of the project alternatives included:
Geographic Information Systems (GIS) were used to inventory resources, evaluate and compare impacts among alternatives, and to prepare graphics for presentations to agencies, the public, as well as the Transportation Executive Committee that participated in the project development process.
ms consultants was retained under a Post-NEPA services contract to coordinate environmental and design commitments with the PTC design manager, section designers, and environmental agencies.
After issuance of the Record of Decision on the Final Environmental Impact Statement, the project was advanced into Final Design with five design sections. PTC engaged ms to develop final design for the fifth subproject, 55C2, located in Cecil Township and South Fayette Township, Pennsylvania.
The first component of 55C2 was a new, four-lane highway with a 60-foot median along the Southern Beltway mainline, state Route 0576.
The design also included widening a three-mile stretch of I-79 from four lanes to six lanes. The widening occurred in the interstate’s existing median, both northbound and southbound. The bifurcated roadway required moment slabs with toe walls to support the extra 24 feet of proposed pavement in both directions.
The team implemented a multiple-phase traffic-control plan to maintain two lanes of traffic at all times. The plan protected the traveling public while the construction team widened the two existing mainline structures and built two new multi-span structures, allowing state Route 0576 to pass underneath I-79.
A second component included relocating 6,500 feet of Morganza Road and 4,800 feet of Morgan Road.
The team designed a roundabout at the intersection of Morganza and Morgan Roads. The roundabout provides efficient traffic operations with a smaller footprint—less pavement, less maintenance, and less operation costs—and, ultimately, a safer intersection.
The project reduces congestion, provides safer travel, and increases development opportunities in the area.