Accessibility is a key ingredient of well-being and prosperity in contemporary societies. The ability of individuals, families, entrepreneurs and firms to exchange goods and services, to be where activities are being carried out, and to interact with people on a regular basis is crucial not only to economic life but also to the quality of life. With the growth of economic and social networks over the course of the past two centuries, and t he spatial dispersion of activities, transportation has become a vital part of the systems providing access to those activities. It is also a crucial.
