Empires were shaped by interactions across borders. The movement and exhange of people and goods have always been central to historical work on empire, but it is only in recent years that explicit discussion of imperial networks across terrestrial and oceanic space has come to the forefront of history writing. This is explained in part by a growing interest in the relationship between imperial spatial forms and the historical roots of globalistion. The main focus of analysis has tended to lie with the places connected and shaped by multiple and overlapping trajectories. There is scope to extend our understanding of the explicit ways in which networks functioned on the ground or at sea, how people, goods and power circulated within and around empires and more particularly, the significance of the transport infrastructures that underpinned these processes.