Jones Road Over Route 4 Bridge Replacement

The project replaced the Jones Road bridge over Route 4 and provided a new bus stop platform with pedestrian walkway and new sidewalks. Stormwater in the project area drains directly to Flat Rock Brook or its tributary. Drainage improvements include upgraded drainage inlets along Jones Road in the vicinity of the bridge and installation of a new additional inlet adjacent to the existing inlet to increase the capture efficiency and eliminate proposed increases to downstream waterways. Nonstructural stormwater management strategies, including replanting disturbed grass wooded areas with brush, and vegetative enhancement to adjacent previously disturbed lawn areas, were designed to lower the overall runoff coefficient of the site and provide an overall reduction to peak flows in post-development conditions.

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. PondPack and InRoads Storm and Sanitary (equivalent to HydroCAD) were used for the routing of the flows within basins and closed drainage systems.