The Rural Highway Mod, or as it is perhaps better known, the RHW, is a modification produced by the NAM Team. The RHW is optional component to the Network Addon Mod, and hence requires the NAM as a dependency. It enables a completely new network that Maxis left unfinished (known internally as DirtRoad), formerly part of the NAM ANT Plugin. Through Override Technology, wider variations of this network, often allowing increased capacity, can be created through draggable means, along with Modular Interchange System (MIS) ramp segments.
Basic Network Characteristics
The RHW network is a Highway-type Network, which means it does not allow access to RCI Zones. Due to the "unfinished" state Maxis left it in, it does not have Tunnel capability, nor can it show up on the Regional Transportation View. RHWs can also be bulldozed using the Dezone tool, much like Streets. It is also a 1-tile network, the only such Highway-type network, which makes it particularly conducive to being overridden by modders.
The base network the RHW Network Tool produces is known as the RHW-2 (RHW, 2-lane). It is a 1-tile, 2-lane, 2-way network, much like the Transit Network#Roads network, but with a higher capacity and speed (dependent on the Understanding The Traffic Simulator one has installed. (The "A" and "B" simulators are recommended for RHW users.)
The RHW-4 is an Override Network of the base RHW-2 network, utilizing a Puzzle-Drag Override to transform the RHW-2, into a 1-tile, 2-lane, 1-way network. It is known as the RHW-4 because the full width of both directions is 4 lanes over 2 tiles, but because it is based on a 1-tile network, the two halves of a full RHW-4 do not need to be adjacent, and can be split, unlike Transit Network#Elevated Highway (without the cumbersome Multi-Highway technique). It has twice the capacity of an RHW-2.
Also unlike the Maxis Highways, the RHW-4 can have at-grade intersections with other networks, in addition to allowing for grade-separated interchanges using the Rural Highway Mod#MIS (MIS).