Thoughts toward autonomous land development Spatial Transformation of Regular grid Irrigation Frameworks Bangkok and Cairo A Work in Progress Information based on student workshop June 2009 and earlier Cairo University collaboration in the 80s. More complete description may be found in Working Paper: TRANSFORMATION OF IRRIGATION FRAMEWORKS. Reinhard Goethert with Gabriel Arboleda, December 2009 1 Introduction Search for guiding land development to meet rapid urban population growth and urban expansion challenges of speed and scale Focus on regular grid irrigation areas on urban fringes Rudimentary comparison of Bangkok and Cairo and their urbanization process. Bangkok looking out Cairo looking in 2 1
Goal is an autonomous passive urbanization guide to parallel informal energy Less ability to control and guide More reliance on outside initiatives Informal dominates CAPACITY POLICIES More ability to guide and control More complex measures Less reliance on outside assistance Formal dominates > What is the least that needs to done to be good enough? 3 Search for preplanned grids as a proactive development tool Capacity of Governments is the key variable in determining a good grid : High capacity: Zoning, effective regulatory structure and enforcement, skilled staff and resources => Can use sophisticated land release measures and zoning controls, and targeted investment to guide and control development Low capacity: Possible zoning and regulatory structure but weak enforcement, weak staff, few resources, largely driven by market and politics? => Goal: automatic grid which requires minimum intervention for guiding growth with low cost and few intervention burdens on public authorities, and offers variety of options for all income sectors (a balanced development is the goal) > Do countries with most rapid growth have lowest capacity? > After disasters, would a preplanned grid facilitate rebuilding? 4 2
Recent growth explosion in Kabul an extreme example? From 1.5 million in 2001, to 4.5 million in 2006 From 1994 2004 a 15% growth rate, now 5% 25,000 units needed annually Approximately 70% of land occupied idi informally What about Haiti and the rebuilding efforts? 5 Key characteristics of a regular grid irrigation pattern Spatial characteristics Covers large area Main fixed grid is formed by canals Secondary interior grids are variable: Length is fixed, resulting from need to connect to canals Width is variable, becomes smaller generally from inheritance Some Conversion Issues Primarily agriculture function, soil may be less suitable for construction Pressure to convert function of: Benefits from agriculture use Land prices Demand Clear initial title before conversion 6 3
Both Bangkok and Cairo exhibit a regular grid irrigation pattern on the fringe Bangkok Fixed depth 2 3 km Cairo Variable width 600 800 m > But the Bangkok grid is considerable larger, approximately 2 3 times 7 Bangkok When drawn to scale: Cairo 8 4
Land development is fundamentally different Bangkok: Complete parcel all at once Cairo: Individual incrementally 1957 Farmer lays out interior street, dependent on property p width. Sells individual parcels legally, but urbanized illegally. Parcels vary as to choice of buyer Developer buys entire parcel and builds gated community. High development costs because of parcel size and expensive construction coupled with economic downturn precludes affordable housing for low income. Three drivers: properties become smaller from 1966 1976 inheritance and farming becomes less sustainable, 2 city expands rising land values, 3 returning workers from Middle East invest in land and build houses. 9 Conversion of canals similar Bangkok Cairo Canal used for water transport, in addition to irrigation Canal with paths both sides for field access Canal transformed into road as area urbanizes Irrigation function lost as area urbanized Road widened for increased traffic induced by growth Filled canal, ready for upgrading into paved road > The former canals provide a width appropriate to main streets > Can the hydraulic gradient of the former canals be effectively used for services? 10 5
Secondary interior streets are formed differently Bangkok the Soi Cairo Developer designed interior access. Paved and serviced as part of community Farmer defined interior access. Who paves and provides services? But over time, it becomes assimilated > But lack public secondary streets 11 Housing parallels development: Large complete developments vs incremental houses Pre-1997 worker housing Recent NHA low income housing Customary high end gated community Developer developed, sensitive to market demands. Fixed units. Previously included affordable housing before economic downturn 1997 99, now NHA builds Informal after 25 years Individual decisions incrementally developed (See: web.mit.edu/incrementalhousing) 12 6
Is competition for land a key factor? Bangkok: All compete for same area Cairo: Variety of opportunities to expand Main development push into areas dominated by marketdriven developers New High End Informal push into NW and S. Higher income compete elsewhere, newest area to SE 13 What is impact of the irrigation grid on Bangkok expansion? What we did I As basic reference, five transects were selected three along main roads, two interior areas Google Maps were basis of data Pink squares are 2m x 2 km segments identified as representative of three stages of development for further study. 14 7
What we did II a In each transect three 2km x km segments were identified for three degrees of development according to distance from city: 0-20 km Heavily built-up, adjacent to city 20-40 km Partially built-up, partially farm land 40-60 m Rural farm land, low penetration of development What we did II b Basic land use data was calculated for each segment - Land use percentage (public-private) - Network length in terms of length/area served - Unit density, both net and gross > Lack of public facilities > No public secondary streets > Densities vary with type of housing 15 What we did III a Four sizes of property width were identified as most common 25m single interior soi, properties on one side 50m single interior soi, properties on both sides 75m -125m variable soi interior pattern >125m variable soi interior pattern > Larger sizes offer more options for development. > Larger sizes preferred by developers What we did III b Number of each width were identified to determine relation to distance from city. > Tendency for larger sizes to be found closer to city, with aggregation of properties into one larger parcel by developers. 16 8
What we did IV Occupants were surveyed in each 2km x 2 km segment to get a sense of location choices and their view on future of the area. Surveys focused on Initial occupation, current situation, and future expectations, for occupants, farmers, and developers. Farmer, Low Density 17 What is the impact on growth scenarios? Five growth scenarios provided a context of spatial growth and the expected impact on the fringe, considering the degree of control required. Finger Five growth Corridors, leaving space for the city to breathe Mesh Mini Centers Even distribution of very small pockets of growth River Spine All growth N S exploiting river transport Compact Restricted expansion, concentrated development Super Subcenters Small new towns surrounding city > The large grid favors market sensitive developers, who may be more controllable by city in supporting growth strategy. 18 9
(An aside: One way to fix (improve) Bangkok grid for more inclusive development?) 2 3 km spacing grid too big Add second main street along the interior division. Minimum amount of land taken Divides distance in half: 2 km down to 1 km. Forms 500 m depth of properties Still big, but manageable Opportunity for a Skytrain extension, with focused access points for high density centers, commercial development 19 Summary: Is the key factor the size of the irrigation grid? (But terms of engagement is different) Bangkok Very large grid 2000 3000m Cairo Appreciably smaller grid 600 800m Inherently less primary infrastructure (streets and services) lowers public burden Provision of secondary infrastructure included in development increases costs Size particular burden on interior circulation Development driven by developers sensitive to market Size provides flexibility in design Mostly higher income with low density of land use Space for public facilities lacking Inherently more primary infrastructure with increased public burden Provision of secondary infrastructure problematic Size for interior circulation within comfortable range Development driven by individual buyer Size provides flexibility in choice Mostly lower income with land saving higher density 20 10
Some concluding thoughts Hypothesis: Bangkok a developer s world, Cairo an individual, incremental world. Hypothesis: Cairo: the right size at the right time for the right capacity? Turner s rural urban trajectory explains squatters on fringes of Cairo and lack of squatters on fringes of Bangkok? Issue: Could a Cairo be duplicated elsewhere? A Goldilocks frame size, ready to sell seller, ready to buy buyer, with former canals providing appropriate p main street frame. Issue: Is the existing land pattern just a curvy grid? Issue: Can a grid be simply imposed on existing properties and achieve same results as irrigation grid? (Is this just land readjustment?) 21 11