STRUCTURES SEMINAR
Department of Architectural Engineering/Department of Civil & Environmental Engineering
The Pennsylvania State University
“SEPTA-MARKET STREET ELEVATED
RECONSTRUCTION PROJECT, DESIGN AND CONSTRUCTION ISSUES”
by
Andrew Haines, Project
Structural Engineer
James Pospisil, Structural Engineer
Gannett Fleming Inc.
Harrisburg, PA
The Southeastern Pennsylvania Transportation Authority (SEPTA) is in the continuing process of updating its transit systems. As part of this modernization, the Market Street Elevated Passenger Rail Line, which serves passengers in the West Philadelphia area, is being rehabilitated. The existing structure was constructed in 1905 and consists of a ballasted track system supported by steel trusses and columns. Due to its age and the current vehicular traffic needs on Market Street, a complete structure replacement is being designed.
The Market Street Elevated Rail Line is part of SEPTA’s Blue Line, which serves approximately 167,000 riders per day. Because of this high patronage and the vehicular traffic needs on Market Street, suspending normal rail and traffic operations is not possible. Therefore, the superstructure, track work, and station structures must be replaced while rail and vehicular traffic needs are maintained. The need to maintain rail and vehicular traffic dramatically complicates the overall goal of replacing the aging structure. As a result, the logistics of the construction must be considered in every aspect of the structural design.
This presentation will highlight the aspects of design affected by the rigorous construction restraints as well as explain some of the unique solutions used to solve the various structural problems.