  We analyse the statistical properties of public transport networks. These
networks are defined by a set of public transport routes (bus lines) and the
stations serviced by these. For larger networks these appear to possess a
scale-free structure, as it is demonstrated e.g. by the Zipf law distribution
of the number of routes servicing a given station or for the distribution of
the number of stations which can be visited from the chosen one without
changing the means of transport. Moreover, a rather particular feature of the
public transport network is that many routes service common subsets of
stations. We discuss the possibility of new scaling laws that govern intrinsic
features of such subsets.
