Towards an Evidence-Based Urban Agenda Engaging at Scale with 21st Century Urbanization Prepared by Professor Shlomo Angel, Director, NYU Urban Expansion Program, for presentation at the University of Zurich, 18 August 2016
The Challenge: Urban planners and policy makers are likely to fail to engage with 21st Century urbanization. We now fail at our core mission: to guide and organize future urban expansion by laying out public works in advance of development. Our master plans are easily ignored because they have no teeth, and our smart city districts, built from start to finish, make no difference. As long as we are confused about our core mission, we will not convince our publics to give us the necessary tools the jurisdictions, the powers and the budgets to do our job.
Message 1: Urban expansion is invisible and therefore typically underestimated: Between 1990 and 2015, the area occupied by cities in more developed countries increased by a factor of ; in less developed countries it increased by a factor of.
Measuring urban expansion: Between 1800 and 2015, the population of Paris, France, increased 22-fold from 500,000 to 11 million while its area increased 250-fold, from 11 km 2 to 2,800 km 2 (animation using historical maps and satellite imagery).
Mega-Regions: The UN Population Division divides the world into two mega-regions: More Developed Countries and Less Developed Countries. The Atlas of Urban Expansion allows us estimate changes in urban extent in these mega-regions.
Population Growth and Urban Expansion: The population of cities in Less Developed Countries doubled between 1990 and 2015, while their urban extents increased by a factor of 3.5 (left). In parallel, the population of cities in More Developed Countries increased by a factor of 1.2 between 1990 and 2015, while their urban extents increased by a factor of 1.8 (right).
Density Decline: Urban extent densities (blue) in Less Developed Countries 3.3 times higher than densities in More Developed Countries in 1990 declined at an average annual rate of 2.1% between 1990 and 2015 (left). In More Developed Countries densities declined at 1.5% during this period (right). Urban land consumption per capita (red) in these regions increased at similar rates.
Urban Extent (2 x GDP) = 1.56 GDP R 2 = 0.77 Urban Extent and City GDP: Differences in urban density and land consumption per capita in these two mega-regions are largely explained by differences in their cities per capita incomes. A simple relationship exists between urban land consumption per capita and GDP per capita: On average, doubling GDP per capita increases land consumption by a factor of 1.5.
Lagos, Nigeria, 2015 Population: 11.4 million City GDP: US$58 billion Urban Extent: 850 km 2 Urban Extent Density: 134 p/ha Land Consumption per Capita: 71 m 2 Paris, France, 2015 Population: 11.2 million City GDP: US$557 billion Urban Extent: 2,803 km 2 Urban Extent Density: 40 p/ha Land Consumption per Capita: 251 m 2 In 2015, Paris had almost the same population but 10 times the GDP as that of Lagos. As a consequence Paris had 3.5 times the urban extent of Lagos.
Estimating future urban expansion: Between 2015 and 2050 the urban population in Less Developed Countries will increase by 2.35 billion, or 18 times the expected increase of 130 million in the More Developed Countries. We can begin to understand how much urban expansion this will entail by looking at past urban expansion.
Estimating future urban expansion: Between 2015 and 2050 the urban extent in More Developed Countries will increase by a factor of 1.9 at the current rate of increase in land consumption, by a factor of 1.5 at half the current rate, and by a factor of 1.1 if land consumption remains constant.
Estimating future urban expansion: Between 2015 and 2050 the urban extent in Less Developed Countries will increase by a factor of 3.7 at the current rate of increase in land consumption, by a factor of 2.5 at half the current rate, and by a factor of 1.8 if land consumption remains constant.
Underestimating Urban expansion in practice: In 2000, the built-up area of Zhengzhou, China was 286 km 2 (light orange). According to its master plan approved in 2009, its built-up area was expected to reach 400 km 2 by 2020. It reached 612 km 2 by 2015 (dark red).
1 4 Message 2: To work at scale, city officials must (1) estimate their future expansion correctly, (2) plan and secure the rights-of-way for future arterial roads, (3) ensure that adequate lands are allocated to streets, and (4) protect key future public open spaces, so as to organize their urban peripheries in a productive, inclusive and sustainable way before development occurs.
1 5 Gouverneur Morris, 1811 Commission Chairman Louis Risse, Chief Engineer, Topographical Department. New York s ambitious expansion plans: The 1811 Commissioners Plan expanded the city 7-fold and the 1900 Board of Public Improvement Plan expanded it again, this time 9-fold.
Barcelona s ambitious expansion plan: Ildefons Cerdá s Ensanche Plan of 1859, expanded its built-up area 9-fold. 1 6 Ildefons Cerdá
1 7 Assembling the evidence on global urban expansion: We identified the universe of 4,231 cities that had 100,000 people or more in 2010; we then focused on a stratified global sample of 200 cities, and within these cities on a set of randomly chosen 10-hectare locales.
The 2010 Universe of cities on a map of world regions. 1 8
The UN Sample of Cities and the eight world regions. 1 9
Pre-1990 (tan), 1990-2000 (orange) and 2000-2015 (red) expansion zones (left), and randomly selected 10-hectare locales in Accra, Ghana. 2 0
Locales in the pre-1990 area (left) and expansion area (right) of Accra, Ghana, 2015. 2 1
Finding 1: 22 Most of the residential fabric in the expansion areas of cities (1990-2015), especially in less developed countries, is unplanned and disorderly, taking place in defiance of municipal plans or regulations.
Residential Fabric 23 Laid Out Not Laid Out Formal Layout Informal Layout From left to right: Formal layout: Minneapolis, USA; Informal layout: Lagos, Nigera; Not Laid Out: Mumbai, India.
Extreme values of the shares of residential areas formally laid out: the expansion areas of Sydney, Australia on left (87%) and of Lahore, Pakistan on right (30%). 24
Share of Residen al Fabric Laid Out Before Occupia on 100% 25 90% 80% 70% Pre-1990 1990-2015 60% 50% 40% 30% 20% 10% 0% East Asia and the Pacific (EAP) Southeast Asia (SEA) South and Central Asia (SCA) Western Asia and North Africa (WANA) Sub-Saharan Africa (SSA) La n America and the Caribbean (LAC) Europe and Japan (E&J) Land-Rich Developed Countries (LRDC) World The shares of residential fabrics laid out before occupation in the pre-1990 areas (gray) and in the expansion areas (orange) in the universe of 4,231 cities by world regions, 2015.
Share of Residen al Fabric Laid Out Before Occupa on 100% 26 90% 80% 70% Pre-1990 1990-2015 60% 50% 40% 30% 20% 10% 0% <$3,000 $3,000-$8,000 $8,000-$20,000 $20,000+ World The shares of residential fabrics with formal layouts in the pre-1990 areas (green) and in the expansion areas (tan) in the universe of 4,231 cities by city GDP per capita, 2015.
Share of Residen al Area that is Laid Out 110% 27 100% 90% 80% 70% 60% Formal Layouts Informal Layouts Not laid out 50% 40% 30% 20% 10% 0% Before 1900 1900-1930 1930-1960 1960-1990 1990-2015 The change in the shares of residential areas with formal layouts,informal layouts and no layouts over time in a representative set of 30 cities.
Finding 2: 28 The paucity of arterial roads in the expansion areas of cities is failing to connect them effectively to metropolitan labor markets, making cities less productive, less inclusive, and less sustainable.
Toronto, Canada s bus and streetcar network, located largely on its arterial road grid, 2010. 29
The absence of arterial roads in a 60 km 2 section of northwest Bangkok, Thailand, 1984. 30
Share of Area Within Walking Distance of Arterial Road 100% 90% 80% 70% 60% 50% 40% 31 30% 20% 10% 0% East Asia and the Pacific (EAP) Southeast Asia (SEA) Share of area w/in walking distance of arterial roads wide and narrow in the sample, post- 1990 and pre-1990. South and Central Asia (SCA) Western Asia and North Africa (WANA) Sub-Saharan Africa (SSA) La n America and the Caribbean (LAC) Europe and Japan (E&J) Land-Rich Developed Countries (LRDC) World The share of built-up area within walking distance (625m) of an arterial road in the pre-1990 areas (orange) and expansion areas (blue) in the universe of 4,231 cities by world regions, 2015.
Share of Area Within Walking Distance of Wide (18+ meters) Arterial Road 32 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% Before 1900 1900-1930 1930-1960 1960-1990 1990-2015 The share of the built-up area within walking distance of wide (18+ meters) arterial roads in the areas of 30 cities built during different time periods
Extreme values of the share of built-up area within walking distance (625m) of an arterial road in Lahore, Pakistan (95%) (left) and Sana a, Yemen (34%) (right). 33
Finding 3: 34 In many cities, not enough land is allocated to local streets, segregating neighborhoods, minimizing redundancy in route selection and creating serious bottlenecks, and impeding the integration of the urban fringe into the city.
The streets in the Comás community in Lima, Peru an organized squatter invasion from the 1960s now integrated into the city are 10-meters-wide. One 160m 2 house there cost $180,000 in 2016. 35
Extreme values of the share of the built-up area in streets: too little land in streets in the expansion areas of Dhaka, Bangladesh on left (12%) and too much land in streets in the expansion areas of Riyadh, Saudi Arabia on right (35%). 36
Share of Built-up Area in Roads and Boulevards 37 30% Pre-1990 25% 1990-2015 20% 15% 10% 5% 0% East Asia and the Pacific (EAP) Southeast Asia (SEA) South and Central Asia (SCA) Western Asia and North Africa (WANA) Sub-Saharan La n America Africa (SSA) and the Caribbean (LAC) Europe and Japan (E&J) Land-Rich Developed Countries (LRDC) World The average share of land in streets in the pre-1990 areas (orange) and expansion areas (gray) of the universe of 4,231 cities by world regions, 2015.
Conjecture: 38 Not enough land in cities is allocated for public open spaces while sensitive open spaces of high environmental risk are not protected from development.
The Role Model, Nantes, France: The share of public open spaces in Nantes in 2009 was above 40% of its area. 39
São Paulo, Brazil, has very little land allocated for public open spaces within a cintiguous built-up area of more than 1,500 square kilometers. 40
Orderly Urban Expansion in Practice The estimated area of expansion of Bahir Dar, Ethiopia, prepared by NYU
Orderly Urban Expansion in Practice Municipal officials from Bahir Dar, Ethiopia, preparing draft plans of the expansion area of their city in an NYU workshop in Addis Ababa, 2013
Orderly Urban Expansion in Practice The arterial grid in the expansion area of Mekelle, Ethiopia, 2010-2040, prepared by municipal officials, 2014
Orderly Urban Expansion in Practice A survey team laying out a road in the expansion area of Hawassa, Ethiopia, where 66kms. of arterial roads have been surveyed and secured (road boundaries are marked on houses).
Orderly Urban Expansion in Practice An arterial road in the expansion area of Mekelle, Ethiopia being graded, 2015
Orderly Urban Expansion in Practice The proposed arterial grid for Montería, Colombia
Orderly Urban Expansion in Practice The proposed arterial grid for Playa del Carmen, Mexico
48 Key Policy Messages Message 1: Estimate urban expansion correctly, based on population and density projections for the next 30 years. Message 2: Create legal and fiscal mechanisms for ensuring that one-third of land on the urban fringe reverts to streets and arterial roads. Message 3: Plan and secure the routes for wide arterial roads, spaced no more than one-kilometer apart, in the entire projected area of urban expansion in the coming 30 years. Message 4: Create the institutional framework for securing key public open spaces, including sensitive areas of high environmental risk, and protecting them from development. * * *