Project Type: Environmental Compliance / Permitting / GIS

Route 54, Route 322 Over Cape May Point Branch and Hospitality Branch

Folsom Boro, Atlantic County, NJ

Arora was responsible for preliminary engineering through completion of construction of this complex interchange project that included the replacement of two bridges, NJ Route 54 over NJ Transit and Hospitality Branch and Route 322 over Cape May Branch, and the deck and pier replacement of the Route 54 over 322 structure.  The project involved the elimination of the existing grade-separated interchange with Route 322 with an at grade signalized intersection, realignment of Route 54 and replacement of the 500’ long Route 54 bridge over Cape May Point Branch Railroad. Stormwater impacts were mitigated by constructing two on-site stormwater recharge basins within the existing interchange infields. Work included engineering studies, plan preparation, and preparing reports to obtain state permits. The engineering studies included analysis of drainage systems impacted by the project, and preparing reports associated with these activities. Scour analysis for the replacement bridge was performed in compliance with state regulations. The project also included preparation of permit plans, soil erosion and sediment control plans and details, permit application submittal, and support for FHWA NEPA Categorical Exclusion documentation. 

The project required the design of detention basins subject to a backwater analysis from the adjacent stream. Stage storage analysis and compensation included the inundation of the basin from the backwater/tailwater effects. A PondPack analysis using TR-55 (equivalent to HEC-MMS & TR-20) to develop the peak basin inflows was used, based on the tributary drainage area. Hydrologic and hydraulic analysis (HEC-RAS) and a scour analysis in compliance with HEC-18 Evaluation Scour at Bridges for the replacement bridge were performed.

Drainage area maps for the pre- and post-developed conditions were prepared to determine the runoff coefficients and time of concentration (Tc) flow path to the inlets and downstream points of analysis. The gutter flow analysis used the delineated tributary drainage areas to determine the inlet spacing required to maximize the inlet interception efficiencies and meet the allowable spread criteria. The pipe collection system used the rational method with a hydraulic grade line analysis to avoid overtopping of the inlets. Pipes were designed to convey the proposed runoff at near full flow meeting the minimum self-cleaning velocities, using the minimum sizes of concrete pipes.