Multiple Nuclei Model by Harris and Ullman

Harris and Ullman proposed Multiple Nuclei Model in their paper The Nature of Cities (1945) to explain the morphology of a city. They argued that the land use pattern is much more complex than the model given by Burgress, Hoyt & Davis. They observed that the land use pattern is neither in concentric zones or elongated corridors.

Basic Idea Behind Multiple Nuclei Model

• In fact, the land use pattern in cities develop around multiple Central Business Districts (CBDs).
• To elaborate, it was argued that there is only one CBD, initially. With the growth of the city size and expansion of economic activities, some of the economic activities from primary CBD shift to other CBDs. The new CBDs are less crowded and more accessible.
• Therefore, the city land-use is found in cellular pattern around these CBDs.

Land Use in Multiple Nuclei Model

1. Central Business District (CBD)

• This zone represents the Central Business District (CBD).
• It is the center of all high end commercial activities.
• So, the land rent in CBD is very high. Therefore, land use is very intensive.
• There are huge business offices and administrative building in this area.
• CBD has negligible residential areas.
• All the transport networks converge in this zone.

2. Wholesale & Manufacturing

• Wholesale & Manufacturing zone is located in proximity to CBD because this sector is dependent on CBD for provision of services.
• On the one hand, the CBD provides services like commercial permits, financial services, transport services etc. to wholesale and manufacturing units. On the other hand, the CBD is provided interest and investment opportunity by this sector.

3. Low Class Homes

• This area is very crowded and inhabited by blue collared workers with low income.
• The residential condition is poor.
• They live in proximity to wholesale & manufacturing to avoid cost of commute.
• This area is well connected to their workplace.
• These workers are located in such a manner that they can provide services to different sector of the economy such as wholesale, heavy manufacturing, services to middle class etc. (see Fig.1)

4. Middle Class Homes

• This zone has the better residential properties occupied by mostly white collared workers.
• The income of the residents is very good, therefore, they can afford the housing in this zone.
• The properties in this zones are detached from each other.
• This zone is characterized by open spaces such as parks, gardens and affluent markets.

5. High Class Homes

• This zone contains the large villas and bungalows of the porch class in sub-urban area.
• It has open space, large gardens and golf courses.
• It is located farthest from the city but these people can commute to CBD.
• Over time, some of the activities of CBD is relocated to suburbs. These include large corporate offices, business activities, trading etc.
• The high class shift their workplace to this new CBD to avoid long hours of commute.

6. Heavy Manufacturing

• When the city grows  horizontally, some of the heavy industries come within the city limits.
• Due to pollution caused by these heavy industries, the administration relocates these to periphery of the city surrounding the working class home (zone 3).

7. Central Business District-2

• Over time, some of the activities of CBD is relocated to suburbs. The new CBD is can be called as CBD-2. For instance, the CBD in Delhi is Connaught place but Nehru Place also acts as a specialized CBD.
• The new CBD emerges because the old CBD becomes very, crowded and land rent becomes exorbitant.
• The corporate houses shift their offices to the new suburbs for better environment for their employees.

8. Suburbs

• The whole city is surrounded by sub-urban zone which presents mixed rural and urban land-use.
• This zone contain small town which acts as CBD for suburban area and provides marketing services.
• The municipal corporation shifts the dirty land-use of city to suburbs i.e. garbage landfill sites, illegal farmhouses, godowns, criminal activities etc.
• This area provides milk and vegetables to the city center.

9. Industrial Suburb

• When the city continues to grow, the municipal corporation shifts most of the polluting industries to suburban areas.
• The new suburban industrial area also serve as a new CBD where workers from suburban area seek work.

Assessment of Multiple Nuclei Model

The multiple nuclei model is most realistic representation of a city. In reality, there are multiple CBDs in a city where the workers go to work. The is mostly true in case of large cities like Mumbai, Delhi, Calcutta etc. The economic activities are divided among the multiple CBDs. Each CBD has their on specialized function.

Application of Multiple Nuclei Model in Indian Context

• Multiple Nuclei Model represents the city scape of Indian cities in nuanced manner.
• In Fig. 1, it is clearly visible that the low class workers (Zone-3) live alongside middle class workers (Zone-4). They provide domestic services to middle class. The high class (zone-5) derives their domestic workforce from the suburban area.
• Take the example of Delhi, it also has multiple specialized CBDs. The Connaught Place is famous for shopping. Nehru Place provides in computer services. Karol Bagh provides automotive services. Chawri Bazaar provides whole services etc.
• The residential areas near these CBDs are very crowded.
• The Municipal Corporation of Delhi is trying to shift most polluting industries to suburbs.
• The garbage landfill site is also located in outer Delhi.

It can be concluded from the above discussion that this model is most practical model of urban morphology. It gives sufficient importance to the land-use planning by the city planners. Hence, it has great relevance to study urban morphology. Its only drawback is that this theory ignores the transport networks and topography.