Structure Design

SAI was responsible for the preliminary engineering, final design, and services during construction for the replacement of a structurally deficient bridge carrying S.R. 0053 over five tracks of the Norfolk and Southern Railroad Mainline in Cambria County, Pennsylvania.

Physical Features: 
  • 324', three-span, continuous steel multi-girder bridge over the Norfolk and Southern Mainline.
  • Minimal amount of roadway approach (25' approach slabs at each end) on a two-lane rural minor arterial with an ADT of 4,389.
  • Deck consists of two 11' lanes with 5' shoulders for a deck area of 10,368 sq. ft.
Other Features: 
  • 77 trains per day, steep rock slopes, and high-voltage overhead lines constrained site access and mobility.
  • Significant coordination with Norfolk and Southern during design reduced issues during construction and during demolition to accommodate a high volume of rail traffic. Roadway profile and the structure depth were set to maximize the underclearance without compromising the structure or the sight distance. 
  • Maintained S.R. 0053 on its existing alignment and eliminated property takes, utility relocation, and additional earthwork.
  • Traffic maintained via detour to expedite construction.
  • Precast approach slabs were used to expedite construction.
  • Abutment spread footing on soil to reduce construction time and cost.
  • Bridge superstructure materials selected for reduced maintenance/repair and future impacts to railroad.
  • Three-dimensional analysis of sharply skewed bridge performed for cross-frame design.
  • Innovative erection method to expedite schedule.
  • Successful project completion on time in 6 months with complete stakeholder satisfaction.