CME performed a formal bridge inspection and load rating evaluation of the existing Hannah Bridge carrying County Route 690 over Indian Run for Salem County in 2009.
The existing bridge was a 2-span timber stringer bridge frame reportedly built in the 1960's. The bridge was framed as a longitudinal stringer system with transverse plank decking. The two spans each measured approximately 11′-5″ for a total span of about 22′-10″ from centerline of bearings to centerline of bearings at the pile-supported timber abutments. The bridge was in serious, structurally deficient condition and was closed to traffic based on the findings provided in February of 2010. CME evaluated the inspection findings and performed a feasibility study to determine if the existing bridge could be repaired or if it required complete replacement.
CME's structural analyses indicated that the existing timber structure would need to be removed and replaced in order to increase the live load carrying capacity of the bridge to the HL-93 loading as specified by the latest AASHTO and NJDOT design guidelines. As a result of the study, the County decided to remove and replace the bridge.
To help improve the hydraulic opening under the bridge, the center pier was removed. Therefore, the proposed bridge that CME designed consisted of a single span precast, prestressed adjacent voided slab beam superstructure. The span length of the new bridge was 29′-0″ from centerline of bearings to centerline of bearings. The superstructure was to be supported by cast-in-place stub abutments bearing on concrete filled 12¾″ diameter steel pipe piles. New steel sheet piling was placed in front of the new abutments to serve as scour protection.
Since County Road 690 had been closed at the existing bridge location since the beginning of the winter of 2010, the demolition of the existing bridge and construction of the new bridge was completed without any construction staging. The design commenced in July of 2010. NJDEP Permits were obtained in March of 2011. Construction began in September of 2011 and was completed in February of 2012.
Post-construction "lessons learned" revolved mainly around the constant and proactive approach of communication between CME, Salem County and the contractor. Jointly, we were able to minimize RFI's and resolve issues quickly. This approach allowed us to efficiently achieve a final bridge that we are all very proud of.