When the Rhode Island Department of Transportation (RIDOT) awarded John Rocchio Corporation the contract to perform a complete replacement of the Mohegan Bridge, the existing structure was deemed structurally deficient, despite its daily demand carrying 15,000 vehicles per day along Route 102 (Bronco Highway) over the Branch River in Burrillville, RI. Foundation support for the new structure was designed and constructed on rock socketed drilled shafts drilled through an existing pier stem.
Initial Cross-hole Sonic Logging (CSL) results for all four of the drilled shafts indicated some anomalies in various locations. Due to slender and tight rebar cage configurations and limited access to the top of the shaft (due to the existing pier stem), coring the drilled shafts and repairing the anomalous zones would have been an expensive and time-consuming effort. John Rocchio Corp. engaged GTR to provide consulting, additional drilled shaft testing and perform an as-built analysis of the drilled shafts to determine if they could carry the intended loads in their as-built state.
GTR performed additional CSL and Cross-hole Tomography (CT) testing and used the results to develop strength estimates of the shaft anomalous zones. The testing results and strength estimates were then used by GTR to carry out a detailed as-built re-design evaluation. Based on our analyses, RIDOT approved the drilled shafts in their as-built condition, thereby saving the project team additional costs and reducing months on the schedule.
