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Shpuza; Urban Shapes and Urban Grids: A Comparative Study of Adriatic and Ionian Coastal Cities

Gallipoli, Makarska). The starkly decreased correlation between fragmentation and integration from actual shapes to shape hulls (figure 8d and figure 8e), shows that these urban grids are sensitive to the fragmentation of actual urban shapes, which results from the combined effect of shape hulls and the size and distribution of holes. In conclusion, biased urban grids best resemble regular orthogonal or Manhattan grids which maintain a few uninterrupted connecting spines; interruptions in the grid occurring due to indentations and holes in urban shapes.

The unbiased-dense urban grids do inhibit even more characteristics of Manhattan grids where most streets cross each other at right angles forming square-like blocks. However, in contrast to the biased type of boulevard grids, these grids maintain the uniformity in both directions and no lines extend and become distinctly more connected than others even in cities developed in elongated shapes (ex. Ortona, Argostoli). The explanation lies on the fact that these cities have developed by patching together a few orthogonal grids rotated in different directions where no single direction is favored. Thus “patched grids” maintain density, uniformity and the lack of sensitivity to shape fragmentation.

Conclusion

This paper proposes a model of relating properties of urban grids to features of the bounding urban shapes. Shape and axial structure are interdependently linked as two-two-dimensional and one-two- dimensional representations of the city as a single system. The analysis with linear maps is a widely used and well-established technique in space syntax. In contrast, descriptions of shape in configurational terms are new and have mostly considered local properties or relations among parts. Three measures of compactness and fragmentation are used for describing urban form, the two fragmentation measures being interrelated. Cities display distinct characteristics from the view point of a close relationship between compactness and fragmentation of their shape hulls. This phenomenon arguably reflects the balancing dynamics between the centrality and visibility in the growth of street networks.

The analysis of urban grid has first considered the patterns of connectivities which have been argued to depict best the geometrical and topological order in grids. Three urban grid types are proposed based on degrees of connectivity and connectivity differentiation: biased grids, unbiased-sparse grids and unbiased-dense grids. The interaction between shape measures and grid integration reveals that the effect of shapes on grid is strongest according to urban types, i.e. according to the principles that underlie the grid morphology. When unbiased-sparse grids are compared to the two other types, two phenomena are observed: first that the effect of shape onto urban grids is more pronounced for biased and unbiased-dense grids; second the two types have higher grid integration. The later illustrates two ways of increasing integration in urban grids: by increasing bias and differentiation of connectivities and by increasing density of connections.

When two rather different scales of built environment of office layouts and urban grids are compared to each other, stark resemblances are exhibited: the interaction between grids and shapes, the peculiar confinement of all linear maps into a defined L-shaped zone in the field of connectivity and connectivity bias, the split into three types, and the increase of integration parallel to the increase of connectivity and connectivity bias.

Proceedings, 6th International Space Syntax Symposium, stanbul, 2007

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