Visual Complexity is a collection and clearinghouse for hundreds of depictions of complex networks, from all over the Internet. Among the many categories, there is one devoted entirely to transportation networks. Here is the goal of the site, in their own words:
VisualComplexity.com intends to be a unified resource space for anyone interested in the visualization of complex networks. The project’s main goal is to leverage a critical understanding of different visualization methods, across a series of disciplines, as diverse as Biology, Social Networks or the World Wide Web. I truly hope this space can inspire, motivate and enlighten any person doing research on this field.
Not all projects shown here are genuine complex networks, in the sense that they aren’t necessarily at the edge of chaos, or show an irregular and systematic degree of connectivity. However, the projects that apparently skip this class were chosen for two important reasons. They either provide advancement in terms of visual depiction techniques/methods or show conceptual uniqueness and originality in the choice of a subject. Nevertheless, all projects have one trait in common: the whole is always more than the sum of its parts.
They clearly have an understanding of the scientific nature of complex networks, which is heartening (especially when social networks and such have become simple buzzwords). Enjoy browsing the site; there is a lot of beautiful information here.