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Dear Chengke, I am afraid that the answer is that the necessary representation as a map is a part of the research question. The way to think about this is: "What is the form of representation of the morphology of the environment needed to best account for observed driver behaviours (eg. flows, speeds etc.)". In the London analysis we found that the best correlations with traffic flow came from the pedestrian axial model on which certain key traffic management measures were NOT represented (for example, Oxford St, the most integrated line in London, is blocked to car traffic for much of its length). When we used an axial map that represented these blockages (along with others) we found a reduced correlation with observed flows. [note. We didn't observe the Oxford St area itself]. This led to the conclusion that what the observed correlation amounted to was either cognitive (driver behaviour and route finding was being informed by their mental map of the city, and that was a more general thing - perhaps pedestrian - in which Oxford St existed as a potential route) or based on land use and development densities which were largely historically determined by flow patterns before the car and modern traffic management restriction, or a combination of both. In the case of Hong Kong, where the road system is complicated by level changes, underpasses and bridges etc. (and so must be cognitively complex) at least on the island - Kowloon is simpler - and where land uses and development densities have changed radically over the very recent past this is even more the case, and I would not care to bet on whether a model with or without traffic management represented would correlate best. The answer might be to model it both ways and set yourself the research question above. By the way there are a number of people working in HK using syntax who you should get in touch with and who might well have better answers: Afroza Parvin at HKU and Bin Jiang at HKPU. All the best, 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 [log in to unmask] www.vr.ucl.ac.uk www.spacesyntax.org > > Dear all, > > I am a master student, currently working on my final dissertation of > applying space syntax to traffic analysis. I need to draw an axial map of > whole Hong Kong territory. I know that Axial map of London consisting > 17321 > lines is successfully done by somebody. > > According to the statements made by Hillier and Hanson in 1984, in the > book > named "The Social Logic of Space", the processing of making an axial map > should begin with the longest straight line, then the second longest, and > so > on until the all convex spaces are covered and all axial lines should > intersect with each other without repetition. How could the creator of > London axial map ensure this principle when he drew the map? > > I know axial line is drawn based on visibility, you can go where you can > see. But in my work, I need to analyze the traffic movement in the city's > street network. Is that justified to draw the lines based on reachablity? > Somewhere in the city, based on visibility, the axial lines should > intersect, but based on reachability they should not. For example, please > see the attached figure1, the axial line 1 should intersect with axial > line > 2 and 3 from the visibility point of view, but should not because street 1 > is not directly intersected with street 2 and 3 (Figure 2), in other world > car driving on line 1 can not directly shift to line 2 and 3. Which > principle should I use, visibility or reachability when I draw the axial > map? > > Any advice will be highly appreciated!