Kaveh,

This issue was addressed in part in Penn, A. and Hillier, B. and Banister,
D. and Xu, J. (1998) Configurational modelling of urban movement networks.
Environment and Planning B: Planning and Design, 25. pp. 59-84.
http://eprints.ucl.ac.uk/archive/00001400/ 

In this research we distinguished between street width (face to face of
buildings) and effective road width (ie. the width open to vehicles
excluding roadside parking etc.). We found that radius integration and
effective road width together accounted for about r^2=.8 in a multiple
regression against flows, but that the same did not hold if we included
street width (face to face of buildings) instead, the contribution of this
variable was much weaker. 

This led to a 'supply-demand' hypothesis: that the demand for flow on a
particular link depends on its place in the network configuration (indexed
in this case by radius integration in the axial map), and that the effective
road width had been engineered over the years to supply road space (width)
according to that demand. Now in central London which operates pretty much
'at capacity' for much of the time that 'engineered' effective width became
a constraining factor in the flows that could be achieved and so became
important in the multiple regression, but we argued that the underlying
demand indexed by radius integration was the primary causal factor. 

More recently Bill and Shinichi have added to this by looking at measures of
angular and metric integration and betweeness in a segment based network (as
well as the original axial or "topological" values) against the same data.
The beauty of this was that a single segment based representation could be
used to measure 'costs' thought of as angular deviation, metric distance and
simply number of decision points (ie. changing from axial line to axial line
is a step of depth as in the original analysis) along a route. They found
that angular and topological measures were strongly related, but that metric
was much less so. This suggested that cognitively metric distance is notthe
key factor in diver navigational decision making but that number of
decisions and angular deviation of the route are much more significant.
Hillier, B. and Iida, S. (2005) Network and psychological effects in urban
movement. In: Cohn, A.G. and Mark, D.M., (eds). Proceedings of Spatial
Information Theory: International Conference, COSIT 2005,Ellicottsville,
N.Y., U.S.A.,September 14-18, 2005. Lecture Notes in Computer Science (Vol.
3693). Springer-Verlag, Berlin, Germany, pp. 475-490. 
http://eprints.ucl.ac.uk/archive/00001232/  I don't think that this has then
been tied back to the involvement of street width, but clearly it could be,
and this would be an interesting thing to do. 

By the way, clearly building height, land use and street width may often
have relations among themselves. So, in the original research we also looked
at other factors such as average building height (in floors), ground level
land use etc. and our observations were carried out with an observation gate
at every street segment in the whole of each case study area. These factors
turned out not to be particularly important in the regression against flows
at a segment by segment level of analysis, but did show effects at a 'whole
area' level of aggregated analysis. 

Alan Penn
Professor of Architectural and Urban Computing
The Bartlett School of Graduate Studies
University College London
Gower Street
London WC1E 6BT
+44 (0)20 7679 5919
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www.vr.ucl.ac.uk
www.spacesyntax.org
 
> 
> Hi
> 
> I just wonder if you can lead me to any papers on the relation between
> syntax
> measures and road-widths. One might think of it as a by-product of the
> natural
> movement particularly in organically growing urban systems. However, I am
> looking for a rather direct theoretical addressing which will be useful
> for my
> study.
> 
> Thanks
> Kaveh Shafiei