I-83 Exit 4, Shrewsbury Interchange

Interstate 83 Exit 4 in Shrewsbury, was experiencing significant increases in traffic volumes due to commercial and residential growth in the area. The high traffic volumes caused vehicles to queue on the off ramps and onto the interstate, creating safety concerns. In addition, the I-83 bridge over SR 851 was structurally deficient, and there were challenges involving the surrounding land, including dense local business use, wetlands, and steep terrain.

To bring the exit up to current traffic safety and capacity standards, PennDOT chose to pursue a full replacement of the interchange and the bridge. The location was determined to be a good fit for a diverging diamond interchange.

Erdman Anthony was selected to provide construction management and construction inspection services for the project.

The project included:

• Replacing the existing I-83 bridge over SR 851 with a wider structure to accommodate additional lanes
• Replacing an existing large metal pipe with a concrete box culvert
• A diverging diamond interchange constructed on SR 851 with two eastbound and two westbound lanes, with traffic signals at the bottom of the ramps
• Aesthetic enhancements including a decorative concrete liberty bell with specialty lighting, flower beds along the bridge and bioretention basins adjacent to the bridge ramps

While this project presented some unique challenges, the interchange was completed on schedule, and the finished project improves traffic safety and capacity for the growing commercial and residential communities served by Interstate 83 Exit 4.

The environmentally conscious designs include natural streambed materials within the box culvert to support aquatic life traveling Deer Creek.