This function is usually called by
konigsberg_graph(). It transforms the
OSM data into a graph object and attaches necessary attributes. It is
publicly exported, however, because it is an expensive operation on large
datasets. If you are trying to calculate a pathway for a large city and would
like to try several combinations of road and bridge filters, then you may
wish to run this function yourself and save the result, then pass it on to
konigsberg_graph() to complete the annotation of the graph.