I'm trying to map the volume of people travelling from various cities to popular mountain towns in British Columbia. I have a CSV containing the starting point, ending point and number of travellers. There must be a way to show the volume of travel (thickness of line, or colour coded) from place to place using city layer polygons and a road network layer.
We have done so using our RW Net 4 package for calculating flow from your CSV-data and then used line thickness for illustration of volume. In this example all flows are from a single location: http://www.routeware.dk/wordpress/?p=61