I am doing a literature search on the issue of permeability (for people, vehicles 
etc) and would be interested to hear if anyone can suggest any significant 
research on its relationship with travel behaviour, particularly in the UK if 
possible.

As some of you may remember I have posted on this subject before.  I coined 
the term 'filtered permeability' to refer to layouts which offer permeability to 
some modes (e.g. walking, cycling) but not others (e.g. private motor 
vehicles).  This can be contrasted with unfiltered permeability i.e. equal 
permeability for all modes, which is offered by the 'traditional grid', for 
example.  I have written a couple of shamelessly unobjective articles on this 
subject in the practitioner press (www.stevemelia.co.uk/articles.htm).  One of 
my supervisors has suggested we might collaborate on an academic article, 
hence this search.

Cozens and Hillier (2008) provides an interesting multi-disciplinary review of 
the evidence, particularly relating to the pros and cons of culs-de-sac and 
New Urbanist grid layouts.  Whereas the sections on crime and housing 
preferences seems fairly thorough the transport sections of this paper are 
fairly short.  Their summary  omits some recent refinements on the relationship 
between transport and the built environment.

There are several papers by people like Cervero, Frank, Gorham, Handy 
Kitamura, using North American data which include a measure of permeability 
(usually just one) in multi-variate models, often seeking to 
compare 'Traditional' or New Urbanist developments with suburban cul-de-sac 
type areas.  

Frank (2008) is unique as far as I am aware in comparing examples of the four 
different possibilities i.e.

1) Low permeability for cars, high permeability for pedestrians and cyclists
2) Vice versa
3) High permeability for both
4) Low permeability for both

This study confirms what we might expect, that the first of these (through a 
layout called the 'fused grid') produces a significantly higher modal share for 
walking and cycling than the others.

In the UK, Hickman and Banister (2008) look at data from Surrey, including 
again a single measure of permeability - grid versus cul-de-sac.  On a simple 
binary comparison the grid form is associated with 5% less transport-related 
energy consumption.  Unfortunately, they did not include this factor in the 
multiple regression; there are clearly many other factors involved in this 
comparison.

Can anyone suggest anything I am missing?

Regards

Steve Melia
University of the West of England


COZENS, P. and HILLIER, D., 2008. The Shape of Things to Come: New 
Urbanism, the Grid and the Cul-De-Sac. International Planning Studies, 13(1), 
pp. 51.


FRANK, L.D. and HAWKINS, D., 2008. Giving Pedestrians an Edge—Using Street 
Layout to influence transportation choice. Ottawa: Canada Mortgage and 
Housing Corporation. 

HICKMAN, R. and BANISTER, D., 2008. Transport And Reduced Energy 
Consumption: The Role Of Urban Planning 40th Universities Transport Study 
Group Conference, January 2008 2008.