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CONNECTIVITY AND COMPLEXITY 6.12 • Hetgram plot of all 60 example networks. The more complex, typically unplanned layouts lie to the upper centre, the more regular, typically planned layouts, lie to the lower right.
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(where complexity is zero). This means that both regular grids and ‘regular’ tributaries will occupy the same region of the diagram. This is clearly the case for Ciudad Lineal (regular grid) and Hilberseimer (regular tributary). The prototype layouts have some of the most extreme values observed. The tendency to extremity is also partly boosted by the size of these networks, which are able to rack up high values of regularity, connectivity, and so on. For example, both Hilberseimer’s New City and Soria y Mata’s Ciudad Lineal have high values of regularity. Overall, the hetgram is useful in distinguishing regular from irregular networks in a quantitative way, and in a broad sense identifying ‘more planned’ and ‘less planned’ networks. This echoes the first basic distinction between planned (or regular) and unplanned (or irregular) layouts noted in Chapter 4. The present analysis allows a quantitative appreciation of this distinction.
CHARACTERISTIC STRUCTURE We can now put together two of the key parameters from this chapter, relative connectivity and complexity, to identify a particular kind of street pattern structure that can be referred to as characteristic structure.