Optimal or historical? The design and evolution of rail transport networks in Australia

Rail began in the cities in Australia in the middle of the 19th century initially as a means of urban transport. Most railways began as private ventures but in response to volatile economic conditions they failed and each were taken over by state governments, because of the essential nature of rail for the growth of each state. In response to the growing rural economy and the discovery of gold in each State, the rail networks expanded rapidly in the latter half of the 19th century. The rail network and the road networks both had their focus on the main port cities which had become the capital cities of each State. The independence of each of the cities and their states can be seen in the different rail gauges that grew outwards from each capital city. This paper examines the rail network that has evolved and asks the question, what would the rail network look like if it were in fact designed with today's current demands? What should the rail network look like if it were designed in some optimal manner2? In order to answer this question, some basic network theory is used to develop what is known as a minimum spanning tree for the rail network. The idea of a scale free network is also explored as a means of describing the rail network. (a) For the covering entry of this conference, please see ITRD abstract no. E216058.