Urban structure is the arrangement of land use in urban areas. Urban planners, economists and geographers have developed several models that explain where different types of people and businesses tend to exist within the urban setting. Urban structure can also refer to urban spatial structure, which concerns the arrangement of public and private space in cities and the degree of connectivity and accessibility.
The term “urban form” is used to describe a city’s physical characteristics. It refers to the size, shape, and configuration of an urban area or its parts. How it will be understood, structured or analyzed depends on scale. Characteristics of the urban form range from at a very localized scale, features such as building materials, facades and fenestration to at a broader scale, housing type, street type, and their spatial arrangement or layout.
Elements of urban structure includes the following.
- Natural environment
- Topography
- Soil types (Bearing capacity)
- Water courses (Rivers, streams and lakes)
- Types of vegetation
- Climate and micro climate
- Environment characteristics
- Landscape features
Types of Urban Structures/Patterns
1) Grid Iron/Rectangular Pattern
The grid plan, grid street plan or gridiron plan is a type of city plan in which streets run at right angles to each other, forming a grid. The infrastructure cost for regular grid patterns is generally higher than for patterns with discontinuous streets. E.g. Plan of Chandigarh city.
Costs for streets depend largely on four variables: street width, street length, block width and pavement width. Two inherent characteristics of the grid plan are frequent intersections and orthogonal geometry, facilitate pedestrian movement. The geometry helps with orientation and way finding and its frequent intersections with the choice and directness of route to desired destinations.
In ancient Rome, the grid plan method of land measurement was called centuriation. The grid plan dates from antiquity and originated in multiple cultures; some of the earliest planned cities were built using grid plans.
Advantages
- Shorter routes
- Easy to extend
- Easy to find places
Disadvantages
- Associated with traffic congestion
- Many intersections/robots
- Time consuming
- Fuel consuming
- Road rage/frustration
Grid system
2) Radial/Concentric system
Radial design offers a method for organizing visual material by arranging it around a central point. Features of radial city pattern include
- Inner outer ring roads linked by radiating roads
- Core has the business area
- Industrial area interspersed within the residential
- Periphery has green belts
Advantages
- A direct line of travel
- Centrally directed flows
- Economics of a single point or origin point
- Less intersections
- Easier flow of traffic
- Aesthetic appeal
Disadvantages
- Central congestion
- Local flow problems
- Difficult building sites
- Unplanned growth can create traffic problems
Radial/Concentric system
3) Linear System
The linear city was an urban plan for an elongated urban formation. The city would consist of a series of functionally specialized parallel sectors. Generally, the city would run parallel to a river and be built so that the dominant wind would blow from the residential areas to the industrial strip. As the city expanded, additional sectors would be added to the end of each band, so that the city would become ever longer, without growing wider. The sectors of a linear city would be
- A purely segregated zone for railway lines
- A zone of production and communal enterprises, with related scientific, technical and educational institutions
- A residential zone, including a band of social institutions, a band of residential buildings and a "children's band"
- A park zone
- An agricultural zone with gardens and state run farms
Advantages
- High accessibility
- Adaptability to linear growth
- Useful along limited edge
Disadvantages
- Very sensitive to blockage
- Requires control of growth
- Lack of focus
Linear system
4) Multi Centered System
City grows from several independent points rather than from one central business district.
Advantages
- Optional locations for focal activities and system terminals
- Good psychological orientation
- Adaptability to existing conditions
Disadvantages
- Depends on stability to key locations
- Potential accessibility problems
- Tendency to dilute focal activities
Multi centered system
5) Irregular System
No set pattern. It develops due to relief. e.g. goes around hilly areas.
Advantages
- Creates aesthetic appeal due to different roads
- Less traffic congestion
- Less intersections
Disadvantages
- Can get lost
- Travel longer distances
Irregular system
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