When inspections identified deteriorating fascia beams on the Mars Road bridge, the Pennsylvania Department of Transportation asked KCI to develop emergency replacement plans. Located in an overly-congested area, the existing structure carried approximately 16,000 vehicles per day. The project was a high priority improvement identified as part of an overall corridor study that had been completed previously. That study called for reconstruction of nine miles of SR 0228, but shifts in funding priorities put the larger project on hold.
To alleviate this congestion, the project quickly grew past a simple bridge replacement to include reconstruction and widening of the nearby roadway and intersection. Overall, the project scope grew due to the conscious effort of placing the needs of the stakeholders in the corridor and motorists at the forefront. By utilizing a big picture approach to transportation infrastructure, what could have been a simple bridge replacement became a segment of a larger corridor improvement in an effort to reduce traffic congestion and improve safety and roadway capacity for years to come.
By expanding the project scope, PennDOT and KCI were able to address the most pressing infrastructure concerns using the construction dollars available to provide the best value for local and regional travelers. The team seized on opportunities during alternatives evaluation to incorporate safety improvements, minimize future maintenance needs, and incorporate sustainable features into the final reconstruction.
The design of the new bridge carrying SR 0228 over CSX railroad called for two continuous spans of welded plate girders that were fabricated of weathering steel. The superstructure is supported on integral abutments and one wall pier. Only five feet of the ends of the beams are painted to provide corrosion protection at the locations where these beams are encased in concrete to facilitate the integral design at the abutments.
Since the new Mars railroad bridge had similar span lengths to the original structure, portions of the existing substructure units had to be removed before the new structure could be built. In some cases, existing piles posed potential interference with new driven piles. KCI minimized the cost of dealing with the existing substructure units by carefully choosing new pile spacing to limit the number of existing piles that needed to be removed. Our team also identified portions of reinforced concrete components of the existing substructure units that were left in place and buried.
To replace this bridge while being compatible with the widening, the project also included the extension of the arch culvert carrying Breakneck Creek and approximately 6,875 feet of roadway reconstruction, including the signalized intersection with SR 3015, Mars/Valencia Road. The widening of SR 228 greatly improves efficiency through the intersection as well as assists in traffic flow up the profile grades. The project also allowed for phased construction of the bridge, which reduced impacts to traffic. The two phases of construction added an aspect of complexity to the already complicated issues of constructing a two-span continuous bridge that required splices.
KCI developed the preliminary engineering and environmental studies for the corridor, which identified various options that addressed the new intended purpose of the project, and presented them to the state. The design team evaluated multiple options for the roadway, ranging from overlay only to complete reconstruction. Ultimately, the most effective approach was determined to be a combination of overlays and full-depth reconstruction. The resulting design saved both time and money in construction by capitalizing on the best combination of both.
The widened roadway section for SR 0228 allowed for phased construction of the bridge, which reduced impacts to traffic. Conceptual traffic control plans for SR 0228/SR 3015 intersection were developed to maintain two-way traffic throughout the corridor by utilizing temporary widening (temporary roadways) while constructing adjacent lanes. More restrictive patterns were only used for crane operations and changes in traffic patterns. Phased construction plans called for the arch culvert widening over Breakneck Creek and proposed bridge structure over the railroad to be built to the south while maintaining traffic on the existing structures. The first phase of construction provided the southern, or widened portion of the new bridge adjacent to the existing structure. The new portion of the bridge was wide enough to carry two full lanes of traffic in the next phase.
The widening of the reinforced concrete arch culvert over Breakneck Creek presented challenges because the hydrologic and hydraulic (H&H) study and model indicated that the existing culvert was of sufficient size to carry flood flows downstream of the structure, but did not have sufficient capacity upstream. Water was backing up behind the culvert during severe storms, creating flooding situations along a nearby property. The design team solved this issue by designing a larger cross-sectional area for a portion of the widened structure upstream, with a smooth transition section to prevent turbulent flow through the barrel of the arch. This funnel shape increases the water holding capacity of the culvert itself while creating a pressure head that forces water through the downstream side at a faster rate.