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Projects

Norfolk Southern Railroad Truss Bridge

New bridges cross an interstate.
  • Norfolk Southern Railroad Truss Bridge-Gannett Fleming

    Construction sequencing for the demolition of the existing bridges and construction of the new truss and thru-girder bridges allowed railroad operations to be maintained on independent superstructures supporting an adjacent track.

  • Norfolk Southern Railroad Truss Bridge-Gannett Fleming

    Extensive agency and consultant coordination minimized disruptions to the traveling public.

Client
Pennsylvania Department of Transportation, District 6-0
Location
Montgomery County, Pennsylvania
Our Role
Preliminary Design, Final Design, Geotechnical, Structural, Construction Services.
Data
Construction Cost:
$270 million
Completed:
2005
Type:
New Construction
Outcomes
  • Extensive coordination with Norfolk Southern, PennDOT, and the contractor’s fabricator and erector throughout design and construction to minimize disruptions to the traveling public.

Some of the fastest growing areas in the Greater Philadelphia Region are located along U.S. Route 202. The area has experienced rapid residential, commercial, and light industrial growth and this road serves as a major commuter route. For more than a decade, PennDOT has worked to increase capacity and relieve congestion on this vital tri-state region link.

Recognizing the need for increased capacity and congestion relief, five miles of Route 202 were widened to six lanes, creating the need for a new bridge to span I-76, new collector-distributor lanes, and a new ramp connecting U.S. 422 to I-76. The new roadway improvements led to the need for two new bridges to carry Norfolk Southern Railroad over the reconfigured area.

What We Did

As lead design engineer, Gannett Fleming performed preliminary and final design services and construction services for a two 240-foot span Warren truss bridge carrying Norfolk Southern Railroad over I-76 (Schuylkill Expressway) and a 102–foot span through-girder bridge carrying Norfolk Southern Railroad over South Gulph Road.

Gannett Fleming developed a sequence of construction for the Warren truss that allowed traffic on I-76 to be maintained throughout construction. Extensive coordination with the agencies, which was initiated during the design phase, continued during the construction phase between Norfolk Southern, PennDOT, and the contractor’s fabricator and erector, minimizing disruptions to the traveling public.

Gannett Fleming’s construction services included coordinating a substantial, multi-party review of the contractor’s sequence and duration of operations for staged demolition of existing bridges and construction of new bridge; fabrication shop submittals; grouting operations; equipment and temporary structure support placement; temporary support of excavation systems; the resulting temporary stresses in the truss members during erection; and effects on maintenance and protection of vehicular traffic.

Key Features

  • Employed allowable stress design process
  • To minimize traffic disruptions along the busy interstate, the balanced cantilever method was used to erect the bridge. Half of the structure was assembled alongside the westbound lanes on four 330-ton rollers, and the other half was assembled in place alongside the eastbound lanes
  • The weekend the 740-ton truss was moved over the highway, traffic was reduced to one lane in each direction and stopped for only 15 minutes. A runway system was used to roll the truss into place using two hydraulic winches
  • Bridge was open to train traffic after one year of construction.

Awards & Recognition

  • Structures greater than 150 feet award, 2004, Pennsylvania Partnership for Highway Quality
  • Grand Conceptor award, 2005, American Council of Engineering Companies of Pennsylvania, Engineering Excellence Awards.

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