JiscMail Logo
Email discussion lists for the UK Education and Research communities

Help for SPACESYNTAX Archives


SPACESYNTAX Archives

SPACESYNTAX Archives


SPACESYNTAX@JISCMAIL.AC.UK


View:

Message:

[

First

|

Previous

|

Next

|

Last

]

By Topic:

[

First

|

Previous

|

Next

|

Last

]

By Author:

[

First

|

Previous

|

Next

|

Last

]

Font:

Proportional Font

LISTSERV Archives

LISTSERV Archives

SPACESYNTAX Home

SPACESYNTAX Home

SPACESYNTAX  2004

SPACESYNTAX 2004

Options

Subscribe or Unsubscribe

Subscribe or Unsubscribe

Log In

Log In

Get Password

Get Password

Subject:

Re: What streets to include in axman

From:

Alan Penn <[log in to unmask]>

Reply-To:

[log in to unmask]

Date:

Thu, 6 May 2004 21:50:19 +0100

Content-Type:

text/plain

Parts/Attachments:

Parts/Attachments

text/plain (95 lines)

Mike,

Well, yes, in Axman you can construct two networks that link to each other
at specific points. We do this all the time to represent multi storey
buildings with multiple staircase connections. The same can be carried out
for different transport networks and this is what Shinichi has done.
However, there are two issues. First, Axman as it stands uses undirected
graphs, and this means that one way streets are not represented as such in
the graph. Second, Axman uses unweighted graphs, and so differences of speed
and capacity on transport networks and their comparison to the pedestrian
mode are not directly representable. In our studies of vehicular traffic in
London the oneway issue appeared to be of relatively little concern. My
guess is that this is because traffic managers use one way systems for two
main purposes. First, to increase capacity by keeping all flows in one
direction on one street and all in the opposite direction in a parallel
street in the grid (eg. Tottenham Court Road and Gower St in London). Thus
correlations between spatial integration and flows are not greatly affected
by the one way nature of the system. Second they use one way systems to
block possible rat runs through part of grid by making a single alignment
have sections with opposing one way flow restrictions (eg. Marylebone High
St.). This can be represented in the axial map by breaking the single line
into the respective one way segments. This seems to work in that
correlations between spatial configuration measures and observed flows are
good - r^2 >.8 . For practical purposes - use in design - the simplicity of
the representation and its explanatory capacity make this a useful tool,
however, I think the representation is somewhat inelegant, and a directed
graph version would be well worth testing out.

Alan 

Does this mean that you can now model the 'Tube' in space syntax. I thought
that this was one of the limitations of it as I have never seen any maps
where anything other than streets are simulated ? except in my Working Paper
80; and presumably by extension, this means that you can model interlocking
networks like a bus network which is separate from a street network in that
only at certain spots does the bus connect with the street at stops etc ? If
you can model different networks then the one way street problem can problem
be handled by modelling two street networks on top of one another which with
an ingenious choice of which network on which to indicate direction, one can
simulate the existence of directionality (although as the street network is
not a graph per se in the relational sense, this is simply a proxy for a
directed graph.

Mike

At 17:52 06/05/04 +0100, Alan Penn wrote:

Victor, Mike et al

The way one does this in Axman is to use the unlink and superlink
tools. This allows you to model freeways that pass over the street grid,
or underground transport networks that connect to the streetgrid only
intermittently at stations. Shinichi Iidas models of London and Tokyo
including both the street level pedestrian/vehicular system and the rail
transport networks have done this on the very large scale and work
rather well. You may need to wait for Shinichi to return from Japan to
get a more detailed review of his findings.

Alan Penn

-----Original Message-----
Subject: Re: What streets to include in axman

I am afraid I don't have any advice about how to handle this problem in
Axman but it is handled consistently in my paper "Distance in Space
Syntax" where I show how you can deal with two different networks such
as railway lines that only intersect with streets at infrequent points
but that this requires a different formalism from traditional space
syntax. Where the railway crosses under or over a street, it does not
normally intersect it. Unfortunately there is no public domain software
to compute this available as yet.

But see the paper at
http://www.casa.ucl.ac.uk/working_papers/paper80.pdf

and Figure 6 et seq in that papers show pictures of where the loop
railway goes under streets in central Melbourne. I think that these
kinds of problems cannot be handled consistently in traditional space
syntax because it requires different networks to be handled and this
means that we need to move to thinking of streets and intersections as
raw data where the Euclidean coincidence of one street with another does
not automatically imply a junction.

Mike

_________________________________________________
Michael Batty, Director, CASA, University College London, 
1-19 Torrington Place London WC1E 6BT, UK
[t] 44 (0) 207 679 1781, [f] 44 (0) 207 813 2843

Personal Homepage 
http://www.casa.ucl.ac.uk/people/MikesPage.htm
New CASA Working Papers at
http://www.casa.ucl.ac.uk/publications/full_list.htm
_________________________________________________

Top of Message | Previous Page | Permalink

JiscMail Tools


RSS Feeds and Sharing


Advanced Options


Archives

November 2017
October 2017
September 2017
August 2017
July 2017
June 2017
May 2017
April 2017
March 2017
February 2017
January 2017
December 2016
November 2016
October 2016
September 2016
August 2016
July 2016
June 2016
May 2016
April 2016
March 2016
February 2016
January 2016
December 2015
November 2015
October 2015
September 2015
August 2015
July 2015
June 2015
May 2015
April 2015
March 2015
February 2015
January 2015
December 2014
November 2014
October 2014
September 2014
August 2014
July 2014
June 2014
May 2014
April 2014
March 2014
February 2014
January 2014
December 2013
November 2013
October 2013
September 2013
August 2013
July 2013
June 2013
May 2013
April 2013
March 2013
February 2013
January 2013
December 2012
November 2012
October 2012
September 2012
August 2012
July 2012
June 2012
May 2012
April 2012
March 2012
February 2012
January 2012
December 2011
November 2011
October 2011
September 2011
August 2011
July 2011
June 2011
May 2011
April 2011
March 2011
February 2011
January 2011
December 2010
November 2010
October 2010
September 2010
August 2010
July 2010
June 2010
May 2010
April 2010
March 2010
February 2010
January 2010
December 2009
November 2009
October 2009
September 2009
August 2009
July 2009
June 2009
May 2009
April 2009
March 2009
February 2009
January 2009
December 2008
November 2008
October 2008
September 2008
August 2008
July 2008
June 2008
May 2008
April 2008
March 2008
February 2008
January 2008
December 2007
November 2007
October 2007
September 2007
August 2007
July 2007
June 2007
May 2007
April 2007
March 2007
February 2007
January 2007
2006
2005
2004
2003
2002
2001
2000
1999
1998


WWW.JISCMAIL.AC.UK

Secured by F-Secure Anti-Virus CataList Email List Search Powered by the LISTSERV Email List Manager