Simple accessibility indicators consider only intra-regional transport infrastructure expressed by measures of motorway length, number of railway stations or travel time to the nearest nodes of interregional networks. More complex accessibility indicators take into account the connectivity of transport networks by distinguishing between the network itself, i.e. its nodes and links, and the “activities” (such as work, shopping or leisure) or “opportunities” (such as markets or jobs) that can be reached by it. In general terms accessibility can be constructed using two separate functions, one representing the activities or opportunities to be reached and the other representing the effort, time, distance or cost needed to reach them...