1378. sredin seminar: Tina Šfiligoj: Access graph: a dedicated graph representation of public transport networks for accessibility analysis
Access graph: a dedicated graph representation of public transport networks for accessibility analysis Tina Šfiligoj
We introduce a dedicated graph representation of public transport (PT) networks, termed the Access Graph, designed to facilitate PT accessibility analysis in a unified manner. The nodes of the access graph represent PT stops, and there is an edge between two nodes if the generalised travel time between the corresponding stops is below a certain cutoff time. In this representation, node degree directly measures the number of nodes reachable within a predetermined time, reproducing traditional measures of access. We study the cutoff-dependent degree distribution of the access graph and observe characteristic values of travel times based on the shape of its structural changes.
In the second part, we present a formulation of accessibility as maximally connected subgraphs of the access graph. We observe the growth of the dimensions of the maximal clique and k-cores for several predetermined values of k. The integral under the curve of dimension of the subgraph w.r.t. cutoff time is proposed as a cumulative access indicator. To give a robust measure that allows for comparison of networks of different dimensions, we define an idealised network on the same set of geographically located nodes and normalise the behaviour of the realised network to that of its idealised counterpart. This allows for directly linking the geographical and topological dimensions of the network.
We apply the methodology to a data set of 51 metro networks worldwide and present a comparative assessment of their access levels.
PS. Kdor bi rad kaj povedal na naslednjih seminarjih, naj mi sporoči naslov teme in doda kratek povzetek.
