Introduction to the Special Issue on the Evolution of Transportation Network Infrastructure

This special issue of Networks and Spatial Economics has the theme of the Evolution of Transportation Network Infrastructure. In economics, the short-term is defined by allowing everything to vary except some fixed input, while in the long-term, even fixed inputs may vary. In that light, this issue concerns the long-term, how and why networks change over time, and what are the implications of those changes. The papers presented here span a breadth of methodologies, from empirical, to counter-factual, graphtheoretic, physical, and political economy. These papers all underwent a rigorous peerreview process and we thank the authors for their patience and their reviewers for their meticulousness. By examining these issues with multiple methodologies, by authors from housed in varied disciplines (civil engineering, economics and business, physics, math, informatics, and environmental studies) perhaps new connections can be made and new questions raised. The first paper (Xie and Levinson 2009a) summarizes and synthesizes the research to date on the topic of the growth of transportation networks. Strands of literature from transport geography, optimization, theoretical and empirical economics, and network science have all approached this issue from different perspectives. The policy implications, of how current investments will shape future choices, are not widely recognized in practice, or understood with confidence in the literature. Bogart (2009) examines the early English Industrial Revolution, prior to the advent of the railway, to consider how network externalities affected the growth roads, canals, and ports. Historical case studies are important as they allow us to see a complete picture of the birth, growth, maturity, (and ultimately decline) of a type of network infrastructure, and so give us the basis on which to test hypothesized models that just examining the current state of infrastructure would be unable to do. In this case, the author finds that there are positive intermodal network externalities, and that the presence of roads increased (or accelerated) the development of canals, as the necessary local feeder road network may have reduced the risks associated with canal development. Netw Spat Econ (2009) 9:289–290 DOI 10.1007/s11067-009-9105-z