Urbanization Models The Central Business District Definition CBD

Urbanization Models

The Central Business District ◦ Definition: CBD- original core of a city’s economy, like a nucleus of a cell CBD is compact, less than 1% of urban land area ◦ But contains a large % of shops, offices, and public institutions ◦ Consumer services and business services are attracted to the CBD because of its accessibility Characteristics of a CBD ◦ High land costs Discourages Industry in the CBD ◦ Intensive land use Skyscrapers All of the following models possess a central business district ◦ Degree of influence and geographic location of CBD varies throughout different models Center is easiest part of city to reach from the rest of the region ◦ Focal point of region’s transportation network Comparative Models of North American Cities

Concentric Zone Model Also called the Burgess model ◦ Developed in 1920’s by E. W. Burgess ◦ 1 st model to explain and predict urban growth All other urban models are built on this model Based on urban growth in Chicago Model suggests that a city’s land use can be viewed from above as a series of concentric rings ◦ As the city grows and expands, new rings are added and older rings change their function ◦ Size and shape of rings vary per city Comparative Models of North American Cities

The five rings: ◦ 1 - CBD innermost ring where nonresidential activities are located ◦ 2 - Zone of transition Contains industry and poorerquality housing Immigrants to city often 1 st live here ◦ 3 - Zone of working-class homes Modest, older homes occupied by stable, workingclass families ◦ 4 - Zone of better residences Contains newer and more spacious houses for middleclass families ◦ 5 - Commuter Zones Beyond the continuous builtup area of the city Comparative Models of North American Cities

The model assumes a process sometimes called invasion and succession (or succession migration) ◦ Definition: New arrivals to cities 1 st tend to move to the inner rings near the CBD This pushes the people and economic activities already present out into further rings In model, the CBD is the premiere land-use ring nearest the point of maximum accessibility ◦ Called peak land value intersection Highest real estate prices Land values decrease as you move away from CBD ◦ Furthest ring the cheapest This constant pattern can lead to a ring known as the zone in transition ◦ Definition: Zone outside CBD Never really developed ◦ Developers know that it will be constantly caught in shift Sometimes called “skidrow” Concentric Zone Model

Bid-Rent curve predicts the land prices and population density decline as distance from the CBD increases Bid-rent curves show the variations in rent different users pay for land at different distances from some peak point of accessibility and visibility in the market ◦ Usually the CBD Transportation costs increase as you move away from the market ◦ Rents usually decrease as distance increases from the market Bid-Rent Curve

Different types of land use generate different bid-rent curve ◦ Ex: commercial retail, industrial, agriculture, housing Bid-rent curves explain the series of concentric rings of land use found in the concentric zone model Model shows a pattern in which architectural form and function of buildings match in each concentric ring and urban land use Bid-Rent Curve

Sector Model was developed by Homer Hoyt in 1939 ◦ Discovered a twist on the concentric zone pattern According to Hoyt, the city develops in a series of sectors, not rings Also based off of Chicago Model grew out of observations that there were urban land-use zones of growth based on transportation routes and linear features ◦ roads, canals, railroads, major boulevards ◦ Not just concentric zones around the CBD Sector Land Use Model

The Sector Model explained that similar land uses and socioeconomic groups clumped together in geometric sectors Certain areas of the city are more attractive for various activities ◦ Sectors radiated out from CBD along particular transportation routes Ex: ◦ Many factories follow rail lines, housing followed public transportation, visitor services along major highways Sector Land Use Model

New Model of urban growth discovered in 1945 ◦ Chauncy Harris and Edward Ullman Unlike previous models that focused on a strong CBD, this model suggested that growth occurred independently around several major focal points ◦ A. K. A. a city is a complex structure that includes more than one center around which activities revolve Ex: airports, universities, highway interchanges, ports Focal points may be distant from “original” CBD and only loosely connected ◦ Suggesting a reduced dominance of the CBD Multiple-Nuclei Land Use Model

The multiple nuclei model reorganized that land use zones often popped up at one, in chunks ◦ Industrial parks, shopping centers, and housing zones could be built in one, giant sweep of construction and be only very loosely connected to the original heart of the city Some activities are attracted to particular nodes, whereas other try to avoid them ◦ Example: A university node might attract pizza places and bookstores The model does not suggest the CBD is not necessarily unimportant ◦ but does show that new areas of intense, urban growth (called nuclei) can grow simultaneously around key nodes of access or industry Multiple-Nuclei Land Use Model

The three models help to understand where people with different social characteristics tend to live within an urban area Can also help explain why certain types of people live in particular places ◦ Uses social area analysis Uses census information to compare characteristics None of the models individually explain why different types of people live in distinctive parts of the city ◦ When combined, more helpful Critics ◦ Models are too simple ◦ Fail to consider the variety of reasons that lead people to select particular residential locations ◦ All three models created between WWI/ WWII The models say that most people prefer to live near others who have similar characteristics ◦ Concentric Zone Consider two families with the same income and ethnic background One family owns a home, the other rents The owner would more likely live in an outer ring and the renter in the inner ring ◦ Sector Model Given two families who own homes, the family with the higher income will not live in the same sector of the city as the family with the lower income ◦ Multiple Nuclei People with the same ethnic or racial background are likely to live near each other No longer relevant Apply the Models

Developed by James Vance in 1960 s ◦ Influenced by increasing importance of automobile ◦ Explained suburban regions that were functionally tied to mixed-use, suburban downtowns with relative independence from the CBD Developed while observing the San Francisco Bay area metropolis Model grew from the multiple-nuclei model Argued nuclei were not just focal points of urban growth but developing into functioning “urban realms” Urban realms model recognized that many people’s daily lives and activities occurred within a fixed activity space within a portion , or urban realm, of a larger metro region ◦ In these “urban realms” on could find suburban downtowns filled with amenities needed for living ◦ “urban realms” Urban Realms Urban Land Model

In the 1960’s, Samuel Borchert studied cities in the United States and linked historical changes to urban evolution ◦ Borchert’s model defined four classical of cities based on the transportation technology that dominated the era when the city hit its initial growth spurt and found it’s comparative advantage Classifications ◦ Stage 1 Hit growth spurt in “sail- wagon” era of 1730 -1830 Mostly near ports and waterways for transportation ◦ Stage 2 “iron-horse” cities Grew around rivers and canals between 1830 -1870 when railroads and steamboats were growing rapidly ◦ Stage 3 “steel-rail epoch” 1870 -1920 During IR, when steel industry blossomed ◦ Stage 4 1920 Linked to air and car travel Borchert Model of Urban Evolution

In contrast to U. S. cities, wealthy Europeans still live in inner rings of the upper-class sector ◦ Not just in the suburbs As in the U. S. wealthier Europeans cluster along a sector extending out from the CBD ◦ Often away from factories, on higher elevations Before electricity social segregation was vertical ◦ Meaning poor people lived in the basements or attics of buildings Today lower income families live outside the inner-city ◦ Mainly outskirts European Cities

Latin American City Structure Model ◦ Also called Ford-Griffin Model Created by Larry Ford and Ernest Griffin ◦ Particularly focused on areas colonized by Spain Most medieval cities in Europe were laid out in unplanned jumbles ◦ 1400 s- Renaissance saw rebirth of Greco-Roman architecture and planned cities ◦ 1573 - Spain passed a law ordering all colonial cities be built according to Greco. Roman designs Prominent, rectangular plazas dominated by Catholic Church and major governmental buildings Latin American Cities

Commercial and residential zones encircled the Latin American plaza ◦ Similar to CBD in North American cities ◦ CBD was most important in the focus of Latin America Suburbanization weaker Other zones Zone of in situ accretion ◦ A region transitioning towards maturity and development that is a mix of middle-income and lowerincome families Zone of maturity ◦ Includes services and infrastructural development In a Latin American city, wealth typically decreases as one moves outward from the downtown area ◦ Typically squatter settlements and rings of poverty are found in rings outside of the CBD Zones of squatter settlements are called Perifericos Latin American City Structure Model