The Pennsylvania Turnpike MP 324-326 Widening Project modernized one of the system’s busiest and most constrained segments near King of Prussia and Valley Forge. After more than 70 years of service, the corridor required reconstruction to enhance safety, increase capacity, and address concerns related to flooding and environmental impacts. The project widened the Turnpike from four to six lanes while replacing aging bridges and upgrading drainage systems to meet current mobility, resiliency and sustainability standards.
What challenges did STV address?
The project was delivered through an environmentally sensitive and geologically complex corridor defined by karst terrain, flood-prone creeks, wetlands, residential neighborhoods and nearby parkland. Unpredictable subsurface conditions required specialized foundation and drainage strategies to minimize settlement and sinkhole risk. The corridor also needed to remain operational throughout construction, which required detailed maintenance-of-traffic planning and phased delivery, as permitting delays impacted the larger Turnpike program.
What solutions did STV deliver?
STV led all engineering and design phases through final construction support, reconstructing the roadway to six 12-foot lanes with full shoulders and a widened median. The firm designed the replacement of three overpass bridges, advanced stormwater infiltration systems calibrated to karst geology, extended culverts and context-sensitive noise barriers. STV coordinated all environmental permitting and developed a phased design approach that advanced a priority segment early, allowing construction to proceed while maintaining schedule and cost control.
How did this project improve mobility and community resilience?
The completed corridor delivers safer travel, reduced congestion and improved flood protection for surrounding communities. Enhanced drainage and infiltration systems reduce roadway closures, while noise mitigation improves neighborhood livability. The widened Turnpike strengthens freight movement and commuter reliability through one of Pennsylvania’s most economically vital regions.
Key Stats and Accolades
- Widened the Pennsylvania Turnpike from four to six lanes between MP 324-326
- Replaced three bridges and upgraded culverts and drainage systems
- Delivered environmentally sensitive stormwater design in complex karst geology
- Maintained Turnpike operations throughout construction via phased delivery
