LDG provided bridge design and engineering services for the replacement of Union County Bridge 24, which carries Ranck Road (T-309) over Penns Creek in Hartley Township, Union County, Pennsylvania. Built in 1904 and rehabilitated in 1949, the original bridge was a 167-foot, single-span, riveted steel through truss. With a curb-to-curb width of 13.8 feet and a posted weight limit of seven tons (12 tons for combinations), which was further reduced to five tons during design due to the continued deterioration of the deck, the existing bridge was structurally deficient and limited in both its capacity and alignment. The goal of the bridge project was to remove the posted weight restrictions; increase the bridge’s width to accommodate two lanes of traffic as well as farm equipment that could be up to 22-feet wide; and to improve the vertical and horizontal alignment to allow emergency equipment to use the bridge. The replacement bridge is a three-span continuous composite prestressed concrete PA bulb-tee beam bridge with a curb-to-curb width of 24 feet. The substructure consists of reinforced concrete cantilever abutments and reinforced concrete solid shaft piers.
Without the posted weight restrictions of the old bridge and with the ability to handle two lanes of traffic, the new bridge eliminated a detour of over five miles that was in place for many users and vehicles including school buses, fuel delivery trucks, and large pieces of farm machinery, some up to 22-feet wide. Because of the increased carrying capacity of the new bridge and the improved vertical and horizontal alignment emergency crews were able to use the bridge, which cut emergency response times by as much as 10 minutes.
The completion of the bridge also provides local residents with two access points to their homes, which is critical in the event of flooding on Penns Creek. The bridge features a larger hydraulic clearance, and therefore a greater hydraulic capacity, than the previous structure. This reduces the likelihood of water overtopping the bridge during flood events and helps to mitigate the impact and severity of the floods upstream from the bridge.
LDG coordinated with Union County, owner of the bridge, and with Hartley Township, owner of the township road carried by the bridge. A questionnaire was sent out to the adjacent property owners along Ranck Road to obtain public input in order to set the proposed bridge width. Additional coordination took place with the West End Fire Department and other first responders regarding the requirements of the replacement bridge; adjacent property owners for temporary construction easements; PADEP for waterway permits, the Pennsylvania Fish and Boat Commission for an aid to navigation plan; and PA One Call and individual utility companies regarding utilities present at the project site.