SR 0722 Bridge Replacement

The Challenge

SR 0722 Bridge over Lititz Run is part of the local history because of its proximity to nearby Oregon Mill, which is listed on the National Register of Historic Places. Structurally deficient and functionally obsolete, however, the existing SR 0722 Bridge comprised two adjoining structures that needed to be replaced to accommodate modern-day traffic demands. Adding to the challenge was the role the existing bridges played in sustaining local bird and fish habitats. The Black-crowned Night Heron—a potential endangered species—prefer breeding near the bridge’s high waters located upstream, and the American shad, a local fish, inhabit Lititz Run. PennDOT wanted the replacement structure to preserve the historic integrity of Oregon Mill yet desired a consultant who could also address the environmental constraints and challenges this bridge replacement project posed.

Our Answer

Using PennDOT’s BRADD software, RETTEW designed a single-span prestressed-concrete spread box-beam bridge with a thicker parapet to allow for architectural surface treatments, which mimic the stone on the historic mill. To ensure that the breeding patterns of the Black-crowned Night Heron remained undisturbed while also allowing the American shad the ability to swim upstream, RETTEW installed grade-control structures in the stream channel. These structures maintain stream characteristics upstream for the birds while reducing water levels for the fish. Additionally, the wider two-lane structure accommodates modern-day traffic demands while preserving the historic integrity of Oregon Mill.