Lewis Bridge

The project consisted of replacing the existing bridge carrying Township Road (T-398) over the Little Mahoning Creek in West Mahoning Township about one mile southeast of Smicksburg in Indiana County, PA. The existing structure, a 102 foot single span, steel through Pratt truss with transverse floor beams and ashlar masonry abutments was determined to be structurally deficient and functionally obsolete. The historic structure was believed to have been constructed about circa 1900 and has been determined to be eligible for the National Register of Historic Places. Gibson Thomas Engineering provided the Preliminary Engineering to obtain the FHWA’s October 29, 2002, approval of the Level II Categorical Exclusion Evaluation/Programmatic Section 4(f) for the project. The services included Field Surveys, Alternatives Analysis, Line, Grade and Typical Section, Preliminary E & S, Preliminary Right-of-Way, Utility Investigations, Hydraulic & Hydrologic Studies, Preliminary Type, Size & Location Studies and Traffic Control Plans for the replacement structure. Gibson Thomas Engineering evaluated alternatives of various impacts to the existing structure including off line studies, replacement with a similar structure and rehabilitation of the existing bridge. The existing structure will be replaced with a Single span (40,578mm) Prestressed Concrete I-beam Bridge with Composite Reinforced Concrete Deck. The out to out width is 8,680mm with two 2,700 mm travel lanes and 1,200 mm shoulders left and right. Gibson Thomas Engineering will also provide the final design services, shop drawing review, construction consultation and construction inspection.


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Gibson-Thomas Engineering Co., Inc. is a multi-discipline consulting engineering firm established in 1916 in Latrobe, Pennsylvania. Our past experience, key staff and commitment to total client satisfaction are the major factors that our clients consider when contracting with Gibson-Thomas Engineering.

724-539-8562
Corporate Office
  • Corporate Office
    • 1004 Ligonier Street
      Latrobe, PA 15650
    • P: 724-539-8562
Pennsylvania Offices
  • Harrisburg Area Regional Office
    • Camp Hill, PA
    • P: 717-612-9880
  • Indiana Area Regional Office
    • Indiana, PA
    • P: 724-471-2246
  • Pittsburgh Area Regional Office
    • Wexford, PA
    • P: 724-935-8188
Florida Office
  • Fort Myers Area Regional Office
    • Ft. Myers, FL
    • P: 239-776-2908
Virginia Office
  • Virginia Office
    • Richmond, VA
    • P: 804-672-4221