Calculating costs (or cost-weighted distance) has applications in many fields. If you were siting a business that needed to be accessible, you could use the ArcMap Spatial Analyst Cost Distance tool to measure distance to important points in a road network. If you were doing animal migration studies, you could use it to measure migration routes. You could also use cost distance calculations to determine sites for new roads, pipelines, or transmission lines. In fact, this approach has been used in Alaska as part of a project to determine the impact of building pipelines. You will work a problem of this type in the Step-by-Step section of this chapter.
It is important to mention another ArcMap tool designed specifically for moving across distances to points connected by linear features, such as roads or railroads. The ArcMap Network Analyst allows you to consider additional factors, including one-way streets and the costs of turning at intersections. Network Analyst is very powerful, and if your problem or application is specific to street or road networks, you should become familiar with this extension. Chapter 9 contains an exercise using Network Analyst.