The Network Addon Mod, or NAM, is a modification for SimCity 4 Deluxe (or SimCity 4 with the Rush Hour Expansion pack), which adds a myriad of new transport network items, ranging from ground light rail, to fractional-angle roads, to roundabouts, and much more. It also includes bugfixes to Maxis items and a highly optimized set of traffic simulator plugins, improving pathfinding accuracy and performance.
This mod is by far the best mod available for SimCity 4. It adds countless transit networks such as trams, elevated roads,and a entirely new highway network. With this newest version, even more heights of roads and new interchanges are added.