SR 2025, SECTION G10 OVER WELTY RUN BRIDGE REPLACEMENT

THE CHALLENGE

The Pennsylvania Department of Transportation (PennDOT), Engineering District 12, proposed the replacement of the SR 2025 (Ankney Hill Road) over Welty Run Bridge located in Mount Pleasant Township, Westmoreland County, PA, due to its poor superstructure and substructure conditions. The existing structure was a single-span rolled steel beam bridge with an open steel grid deck and stone masonry abutments. The surrounding topography and environmental features directly adjacent to the bridge consisted of a steep hillside in the northwest quadrant, an existing farm property in the southeast quadrant with archaeological potential, and a parallel stream in the northeast and southwest quadrants resulting in a 60° skew of the stream to the roadway. The western abutment of the existing structure was heavily impacted by scour and undermining due to the skew of the stream. So much so that shotcrete facing, concrete aprons, and rock stabilization had been added to the existing structure to stabilize it from further stream encroachment. McCormick Taylor was tasked with improving these conditions and enhancing travel movement throughout the area.  

HOW WE HELPED

McCormick Taylor was awarded the project under an existing Open End contract with PennDOT District 12. Services performed included preliminary and final roadway and bridge design, erosion and sediment control plans, drainage design, hydrologic and hydraulic studies, traffic control plans, public involvement, and construction consultation. The design resulted in the following improvements.

• The existing 20 foot out-to-out bridge width was widened to provide two 10 foot lanes and two 3 foot shoulders in the new structure.
• Approximately 160 feet of approach roadway was widened and reconstructed to meet current PennDOT DM-2 Criteria.
• The new structure layout was set by holding the location of the eastern abutment and shifting the western abutment further west away from the stream to help mitigate future scour and undermining issues.
• The new 17 inch deep spread box beams and 8 inch composite concrete deck required lowering the low chord to maintain the roadway profile limiting the approach roadway reconstruction length and related impacts. To avoid stream impacts due to the lowering of the low chord, the span length of the structure was increased.  
• Vertical wall barriers were provided to minimize the overall structure width and U-wings were utilized at all four corners to reduce the structure footprint and mitigate potential impacts associated with excavation and grading.
• New MASH-compliant guiderail, crashworthy attenuating devices, and bridge barrier transitions were incorporated at each quadrant of the widened structure. The roadside embankment was also regraded to meet all MASH requirements.
• Coordination with the local school district was performed to ensure school buses could be accommodated during the construction detour.

RESULTS

The new widened structure improves movement through the area by all vehicles. Larger delivery vehicles can now use SR 2025 as a connection from SR 982 in the north to SR 2021 in the south. SR 2021 is the main route into the Donegal/I-76 (Pennsylvania Turnpike) Interchange. Using SR 2025 eliminates the need to travel through the towns of Kecksburg and Mammoth, where horizontal and vertical grades make it difficult for larger vehicles to navigate.

The completed design also reduces the water surface elevations for future storm events in the completed condition, mitigates the previous scour and undermining issues that had plagued the existing structure, and provides a low-maintenance and sustainable superstructure type.

McCormick Taylor’s construction estimate was within the contractors’ bid range of -7% to +11% and only two contractor Requests for Information (RFI) were submitted during construction.

AWARDS

2023 Project of the Year Award ($3M or less), ASHE Southwest Penn