he Susquehanna River Bridge between Plymouth Borough and Hanover Township in Luzerne County had become structurally deficient and functionally obsolete. Connecting communities for over 50 years, the time had come for it to be replaced. There were many challenges, both technical and context-sensitive, that the new design had to address:
- Twelve miles of trails on the top of the levee system on both sides of the river were being developed and required connections to key bridges within its reach.
- The proposed alignment of the new bridge crosses a valley heavily mined for coal, requiring that filled shafts and mine workings be avoided.
- The river hydraulics are complicated because the new bridge crosses the Susquehanna River in a region where it is divided into two channels by a low, sandy island.
Working with the public and affected stakeholders, our creative bridge engineers developed both a concrete and steel alternative for the $25 million, 2,400-ft crossing. The south abutment was designed to allow for direct access from the bridge sidewalk to the pedestrian/bikeway trail on top of the levee. Modjeski and Masters also developed a variety of foundation types to accommodate the variable depths to bedrock – friction piles, end bearing piles and spread footings. In addition, our experienced engineers optimized the hydraulic efficiency of the substructure by using three different foundation orientations – one for each of the three flow regions of the river. And to add value and savings during construction, the pier shafts were constructed normal to the longitudinal axis of the bridge. This was one of the first major bridges in the District which used the “Modified Turnkey” method of project delivery.
|Length of Main Span||150 Feet|
|Total Project Length||2,400 Feet|
|Number of Lanes on Structure||Two Lanes in each direction|