  It is well received in the space syntax community that traffic flow is
significantly correlated to a morphological property of streets, which are
represented by axial lines, forming a so called axial map. The correlation
co-efficient (R square value) approaches 0.8 and even a higher value according
to the space syntax literature. In this paper, we study the same issue using
the Hong Kong street network and the Hong Kong Annual Average Daily Traffic
(AADT) datasets, and find surprisingly that street-based topological
representations (or street-street topologies) tend to be better representations
than the axial map. In other words, vehicle flow is correlated to a
morphological property of streets better than that of axial lines. Based on the
finding, we suggest the street-based topological representations as an
alternative GIS representation, and the topological analyses as a new
analytical means for geographic knowledge discovery.
