Public transport systems in 22 Polish cities have been analyzed. The sizes of these networks range from $N=152$ to 2881. Depending on the assumed definition of network topology, the degree distribution can follow a power law or can be described by an exponential function. Distributions of path lengths in all considered networks are given by asymmetric, unimodal functions. Clustering, assortativity, and betweenness are studied. All considered networks exhibit small-world behavior and are hierarchically organized. A transition between dissortative small networks $N\lesssim 500$ and assortative large networks $N\gtrsim 500$ is observed.

• Received 8 June 2005

DOI:https://doi.org/10.1103/PhysRevE.72.046127