North Perimeter Contractors, LLC manages the I-285 and GA 400 Interchange Reconstruction Project. The project includes constr ... uction of barrier-separated collector-distributor (CD) lanes along I-285 and SR 400, new flyover bridges, reconstruction of existing ramps, and reconstruction and widening of existing bridges in the interchange area. “Braided” ramps are being constructed in the vicinities of Ashford Dunwoody Road and Roswell Road to eliminate conflicts between traffic entering and exiting SR 400 and traffic entering and exiting the Roswell Road and Ashford Dunwoody interchanges, while preserving the recently completed projects at both of these interchanges. Along SR 400, the project involves the construction of two miles of improvements from Glenridge Connector north to Hammond Drive. The project also includes a collector system north on SR 400 to Spalding Drive, with modifications of the existing north facing ramps at Hammond Drive and reconstruction of the Abernathy Road interchange. read more