Interstate 81 is a vital trucking route along the Appalachian corridor and in particular, south central Pennsylvania. Years of heavy traffic and the harsh Northeast weather abused the parallel bridges spanning Leitersburg Road near Greencastle.
The conventional concrete bridge decks and steel girders on both the northbound and southbound bridges were in poor condition and needed to be replaced. Without any economical detours available, one of the main challenges the Pennsylvania Department of Transportation (PennDOT) faced was how to rehabilitate the structures and maintain both lanes of traffic in each direction throughout peak traffic times.
The entire article can be found on the Roads & Bridges website by clicking the link below: http://www.roadsbridges.com/use-precast-grid-deck-supports-staged-construction-and-accelerates-superstructure-replacement