Public spaces, resilience and urban prosperity: an evolutionary approach to urban development

Transcription

1 Public spaces, resilience and urban prosperity: an evolutionary approach to urban development SERGIO PORTA Urban Design Studies Unit VITAL PUBLIC SPACES: Designing and managing public spaces for inclusive, safe, resilient and sustainable cities UNECE Housing and Land Management Unit Palais des Nations, Room VIII, Geneva, Switzerland Tuesday 24 February

2 CONTENTS 1. CITIES AND PLANNERS IN AN EVOLUTIONARY PERSPECTIVE: The art of being (very) late at the party and showing off 2. GETTING THE STRUCTURE RIGHT: Streets, streets and streets again: the rest can only follow 2

3 1. CITIES AND PLANNERS IN AN EVOLUTIONARY PERSPECTIVE Shots of beauty The Quality Without a Name Maggie Moore Alexander,

4 15 billion years ago Today Cultural evolution Genus Homo Organic evolution PM PM Chemical evolution Geologic evolution Nuclear evolution Billions of years First appearance Origin of Universe Homo Habilis (earliest member genus Homo) 2,300,000 of years ago In COSMIC evolution 23h 59m 46.8s (13.3 s.) Human Culture (symbols, language, lithic technology) 50,000 years ago In MAN evolution 23h 59m 59.7s (2.3 tenth of s.) Origin of Earth First Life First Man Human Culture Millions of years 15-12,000 6,000 3,500 2,800 0,05 Precambrian Stages of cosmic evolution billions of years ago Paleozoic Mesoz. Cenoz. 4

5 50,000 years ago Today PM PM Cities Planning Planning evolution Urban evolution Cultural evolution (since Uruk, Mesopotamia) 6,500 years ago (since RPAA, 1923) ca. 100 years ago In CULTURE evolution In CITY evolution 20h 52m 48s 23h 37m 51s (3h 7m 12s.) Thousands of years First appearance Years (22m 9s.) Symbols Language Lithic tech First City First Planner s 50,000 6, Stages of cultural and urban evolution Thousands of years ago 5

6 1. CITIES AND PLANNERS IN AN EVOLUTIONARY PERSPECTIVE Evolution: diversity AND unity 6

7 1. CITIES AND PLANNERS IN AN EVOLUTIONARY PERSPECTIVE Beauty does not come by design. Structure does. CREATIONIST SHORTCUT System B EVOLUTION DIVERSITY Developing projects UNITY Permanent structure BEAUTY The resilient, prosperous, inclusive, safe and walkable city EVOLUTIONARY APPROACH 7

8 2. GETTING THE STRUCTURE RIGHT Five things that we think we have understood about the structure Cities are, fundamentally, a product of streets. Streets, and Main Streets in particular, are the first and most important constituent of city structure. If you don t get the streets right, you ll never ever get the city right. 1. One important feature of good urban streets: main streets cross about 400mts or less apart, and they tend to remain stable in time. We call this property The 400mts rule. 2. In cities you need a range of densities, building types and plot sizes: this diversity must be closely related to the hierarchy of streets, so that main streets are the backbone of urban communities. We call this property Main Street Orientation. 3. Loosely speaking, though you need a diversity of plots types and sizes, one rule applies consistently in good city structures: plots are kind of small. We call this property: Small Plots. 4. Nobody draws plots any longer, but in fact a good city structure is based on plots which develop independently from each other in time. We call this property Disjointed Development. 5. The structure of good cities always includes simple, short regulations that do not refrain, but actually trigger, people s direct and personal intervention on their environments. We call this property Informal Participation. 8

9 2. GETTING THE STRUCTURE RIGHT The 400mts Rule: getting the right scale Porta, S. Romice, O. Maxwell, A. J. Russell, P. Baird, D. (2014), Alterations in scale: Patterns of change in main street networks across time and space, Urban Studies, Vol. 51(16), DOI: / Historic Origin Type 1 Ancient 2 Medieval 3 Renaissance 4 Baroque 5 Industrial 6 Garden City 7 Radiant City 8 New Urbanism 9 Informal Settlements Medieval: Lubeck, DE Industrial: Chicago, USA 9

10 2. GETTING THE STRUCTURE RIGHT The 400mts Rule: Main Streets will be forever main Porta, S. Crucitti, P., Latora, V. (2006), The Network Analysis of Urban Streets: A Primal Approach, Environment and Planning B: Planning and Design, 33(5). Strano, E. Nicosia, V. Latora, V. Porta, S. Barthélemy, M. (2012), Elementary processes governing the evolution of road networks, Nature Scientific Report, Vol. 2(296), DOI: /srep STREET CENTRALITY Movement (people) Opportunities Economy BETWEENNESS CLOSENESS STRAIGHTNESS Safety 10

11 2. GETTING THE STRUCTURE RIGHT Main Street orientation: communities around streets Mehaffy, Porta et al. (2010) The Emergent Neighbourhood model. Porta, S. Romice, O. (2014), Plot-based urbanism: towards time-consciousness in place-making, in Mäckler, C., Sonne, W. (Eds.), Dortmund Lectures on Civic Art/Dortmunder Vorträge zur Stadtbaukunst, Sulgen, DE: Niggli, p Mehaffy, M. Porta, S. Rofè, Y. Salingaros, N. (2010), Urban nuclei and the geometry of streets: The emergent neighborhoods model, Urban Design International, Bologna, Italy Al Hofuf, Saudi Arabia Source: Duany Plater-Zyberk and Company (2003), Lexicon of New Urbanism, 11

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