PennDOT presents 26th Street/I‑79 interchange study; diamond interchange ranks highest

Mark (S7) and Steve Stewart of Michael Baker (S8) presented findings from an interchange study covering the 26th Street/I‑79 area and outlined three build alternatives — diamond, diverging diamond (DDI) and single point urban interchange (SPUI). They described existing conditions (six bridges, winter maintenance challenges, and crash clusters at a U‑turn and at Rudolph Street) and presented a scoring matrix that favored a traditional diamond interchange driven largely by lower construction and bridge costs.

"We looked at 2020 to 2024, 83 reportable crashes, 69 of them were injury crashes," the consultant said, characterizing a higher‑than‑expected share of injury crashes and identifying crash clusters near the U‑turn area. The presentation reviewed operational analyses, environmental screening and three concept drawings; the diamond option produced the fewest and smallest bridges and scored best on lifecycle and construction cost criteria.

Planning‑level costs were discussed. "We had some planning level cost. It's a hair under $20,000,000 with Diamond," a presenter said. Next steps include more detailed environmental investigation, preliminary design and formal stakeholder and public engagement; planners noted none of the alternatives touch I‑79 mainline lanes and that long‑term sequencing and lifecycle comparisons with a targeted repair strategy will inform final recommendations.