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Life-Cycle Engineering Services | EXPANDED

Modjeski and Masters is pleased to announce the acquisition of structural engineering firm Summit Engineering Group, Inc. Our combined engineering prowess and respective technical skillsets will enable us to provide streamlined design and construction solutions to best meet client needs.

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New Monongahela River Cable-Stayed Bridges

| View Projects:USA Pittsburgh, PA

  • Client:

    Pennsylvania Turnpike Commission
  • Service:

    Cable-Stayed Bridges
  • Status:

  • Overview

    Motorists depend on Pennsylvania’s highways and bridges to stay connected – to both their communities and industries. That’s why the Pennsylvania Turnpike Commission established an ambitious, 13-section design plan as part of the Mon/Fayette PA Route 51 to I-376 network to reduce congestion, improve safety, and stimulate social and economic development in the Monongahela River Valley. A critical part of the plan, Section 53D, called for the design of a long span bridge over the Monongahela River. Requiring the services of a trusted and experienced bridge firm, the Commission turned to Modjeski and Masters to design Section 53D, the crown jewel of the 24-mile Mon-Fayette Expressway.

    M&M began by performing a rigorous bridge type selection study to identify the most suitable bridge crossing. Working with the Commission and various stakeholder groups, our technical experts established evaluation criteria for comparing the alternatives, including cost, constructability, lifecycle maintenance and aesthetics. Next, our problem solvers used this criteria to develop multiple truss, arch and cable-stayed bridge alternatives. In the end, the dual composite cable-stayed bridge alternative proved to be the most cost competitive, durable and aesthetic choice. Modjeski and Masters completed preliminary design of the cable-stayed bridge, including a study to optimize the tower geometry for both performance and appearance. From this study, our engineers identified a hexagonal tower base cross-section – an innovative solution that reduced the crossing’s overall footprint and impact on the waterway.

    Although no completion date for final plans has been established, Modjeski and Masters helped bring the Commission’s vision one step closer to reality. And our personally invested team of engineers stand ready to help the Commission on future endeavors. It’s all part of continuing our long-term relationship with the Commission. It’s how we help construct and maintain great bridges that connect people and the communities they serve.
  • Description

    Tasks Performed
    • Alternatives Matrix
    • New Structure – Preliminary Design
    • Design Visualization
    • Highway/Interchange Design
    • Structural Analysis

    Bridge Geometry
    • Length of Main Span – 1120 feet
    • Total Project Length – 2330 feet
    • # Lanes on Structure – Four lanes in each direction
  • Testimonial

    The bridge that has emerged from the design process represents a combination of innovative ideas and efficiencies from around the world, blended into a unique and visually attractive structure. Members of the Turnpike’s engineering staff were very much a part of the project team, and were instrumental in obtaining such a positive outcome.
  • Credits

    Todd McMeans, PE (Principal-In-Charge)
    Dr. Thomas Murphy, PE (Project Manager)
    Dr. Philip Ritchie, PE (Project Engineer)
    Daniel Irwin, PE (Project Engineer)
    Adrienne Crider, PE (Project Engineer)
    Edward Rickenbach (Project Technician)