Todd Litman wrote to the list on 22 November drawing attention to 
Australian Bureau of Transport Economics Working Paper 39, "Urban 
transport models: a review".  He concluded that "it seems to be a 
good overview of available models".  I would like to put forward a 
different assessment of the paper.  

As a developer and user of land-use/transport models, I wouldn't for 
a moment wish to disagree with the review's conclusion that further 
development and wider use of such models is the best way forward.  
However, the actual content of the review is mediocre and in places 
misleading.  The method used is mainly to describe "typical" examples 
of different types of models: this obscures critical differences 
between models within the types, and gives rise to some unjustified 
criticisms as well as some unnecessary confusion.  For example

- it is stated that "linked land-use/transport models" represent 
_early_ attempts to integrate the land-use system with the 
transport system - in fact, nearly all the most recent 
developments (including MUSSA, CUFM, URBANSIM and my own firm's 
DELTA) are linked models (and several of them have all the 
characteristics which the paper ascribes to "integrated" models);

- it is implied that "integrated land-use/transport models" can be 
represented by the Lowry model, which is scarcely typical of 
current practice;

- there is considerable discussion of the differences in transport 
modelling between "behavioural transport models", "integrated 
land-use/transport models" and  "linked land-use/transport 
models",  which ignores the fact that the transport models used in 
these three categories are often the same in design and sometimes 
actually the same software;

- linked models (in which I admit to having a particular interest) 
are criticised on grounds which are just not true of current 
practice, such as having the trip distribution modelling 
duplicated in the land-use and the transport components.  

It is unfortunate that there is no one published document that I can 
suggest as a wholly satisfactory alternative to the BTE review, but I 
would be happy to provide details of what is available (including 
papers written with or by competitors!) to anyone interested.   

David Simmonds


David Simmonds Consultancy
10 Jesus Lane Cambridge CB5 8BA England
Phone +44(0)1223 316098 Fax +44(0)1223 313893
e-mail [log in to unmask]


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