We have added a new function for calculating traffic flows in RW Net 4. Input is a list of traffic volumes between A to B. Task is to add up all these volumes and get a total flow on each link in the street network. Not so difficult doing on your own, if using node-2-node routing, but we have also added support for dynamic segmentation and keeping track of flow in both directions. This makes it an excellent tool for more simple situations, where you have decided an all-or-nothing approach is sufficient.
On the map to the right, all flows start at the red dot, and spread out in different directions like a tree.
More on this at Wikipedia.