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Title: City shape, entropy, and street networks
Author: Mohajeri Pour Rayeni, N.
Awarding Body: University College London (University of London)
Current Institution: University College London (University of London)
Date of Award: 2013
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Cities are among the most complex man-made structures ever generated. This complexity is reflected in the structure of street networks, which form a part of the field of complex networks. Street networks have distinct geometric properties that are controlled partly by internal (social and economic) and partly by external (geographic) parameters. Analyses of the street networks of 50 cities (with a total of 823,202 streets) from widely different areas (Brazil, Britain, Chile, and Iran) indicate, first, that landscape constraints (the sea, lakes, mountains, valley, and rivers) have large effects on the general shapes of cities and the configuration of their street networks - in particular on the lengths, trends, and associated entropies. The length entropies are mostly controlled by the space available for the network growth, whereas the trend entropies are mostly controlled by the shapes of the constraining landscape features. Second, the results also indicate significant geometric differences between the street networks of the inner (older) parts and the outer (more recent) parts of cities. More specifically, the inner parts have lower Shannon/Gibbs trend/length entropies - are more tightly ordered and with denser networks - than the outer parts. Entropy and street length increase, as a result of spreading, with distance from the inner parts. Tracing the evolution of several networks indicates network growth through densification and expansion and a gradual increase in entropy over time. The results also indicate that larger cities have fewer streets and less total street length per capita than smaller cities, indicating that as the city size increases its street network becomes more energy efficient. In conclusion, the entropy measures and the visualisation techniques introduced in this work offer new methods for analysing street (and other) networks worldwide, including their complex geometrical variations in space and, where appropriate, their development through time.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available