The relocated Route 403 project entailed the design of a new freeway extending form Route 4, north of Frenchtown Road in East Greenwich, to the Quonset Business Park in North Kingstown, RI. The distance of the freeway is approximately 4½ miles, not including several additional miles of interchange ramps and new roadways, which comprise a total of 14.8 miles of roadway on the project. The scope of work included thirteen bridges; the relocation of existing streets and roadways, including a half-mile relocation of Post Road (U.S. Route 1); six permanent and two temporary traffic signalized intersections; construction of temporary roadways and bridges; and extensive facilities for controlling storm water runoff and for protecting groundwater aquifers and freshwater wetlands.

The project’s location being within the watersheds of eight distinct watercourses, one being the Hunt River, a sole-source aquifer and major source of water for the towns of Warwick and East Greenwich in Kent County, required the preparation of a comprehensive Environmental Impact Statement (EIS). The conceptual design phase was most critical to the project because the freeway corridor traverses these watersheds.

Following a major study involving options for the sequencing and scheduling of multiple construction contracts, GRA recommended a program that ultimately involved the advertising of eleven separate construction contracts. Services for the final design efforts of the separate contracts was completed under a master plan that allowed the new freeway to be built over a period of several years under multiple construction contracts, all controlled by specific annual budgets.

With respect to storm water management, the project design included the following:

• Evaluating over two square miles of watershed within the Towns of North Kingstown and East Greenwich. These watersheds included portions of the Hunt River, Fry Brook, Frenchtown Brook, Pine River, Sand Hill Brook and Mill Creek. 
• Quantitative hydrologic analysis on the existing and proposed watersheds and the development of a drainage system to prevent adverse impacts to adjacent and downstream floodplains, water surface elevations, water quality and groundwater.
• Hydrologic analysis included the determination of peak discharge rates for the 2-, 10-, 25- and 100-year storm events; the calculation of stream profiles and flood elevations; the design of approximately 13 miles of closed drainage systems; the design of channels and swales, including impervious-lined (with bentonite) ditches for the containment of sodium-tainted runoff from the new freeway to prevent infiltration into the groundwater; the design of ten water quality basins; and the creation of new wetland areas to compensate for the unavoidable filling of existing wetlands.
• Preparation of all State and Federal environmental regulatory permits.