𝖶𝗋𝗂𝗍𝗂𝗇𝗀 𝖳𝗂𝗉𝗌 𝖿𝗈𝗋 𝖫𝗈𝗌𝖾𝗋𝗌

𝐖𝐨𝐫𝐥𝐝 𝐁𝐮𝐢𝐥𝐝𝐢𝐧𝐠: 𝐂𝐢𝐭𝐲 𝐒𝐭𝐫𝐮𝐜𝐭𝐮𝐫𝐞 𝐌𝐨𝐝𝐞𝐥𝐬

Every city provides an array of service, residential, and industrial  functions. How these services are arranged in relationship to one  another is what we call the urban structure, or the land use structure.

There are three modern models used to describe these structures, which were based on observations of the North American city, as well as some additional models that help explain unique situations and antiquity. However, it is important to note that not every city falls into one of these models. These models attempt to explain larger organizational trends of people/services seen in existing cities. They do not dictate ultimate city form. In  other words, you couldn't use these models to decide whether or not  your street patterns are gridded or irregular, you couldn't use it to  decide whether or not your city is planned, circular, square, or organic  in form. You could design a grid city that fits any of these models  for example! City form is only influenced, not dictated, by your urban structure.

Thus we can conclude that an urban structure model is more theory on  the spacial relationships goods, services, and people need and have to  one another in a city, and city form is your physical implementation of  these ideas.

I am going to explain each model and then point out the Take-Aways, or the critical content and concepts that will help you in deciding and designing your city. Consider it your TL:DR version.

So! before we delve into this, I want to explain what a city 'core'  is, mostly because it gets referenced quite a bit when discussing the  models. A city core is the area of the city where the flow of people, culture, goods, services, information, etc is most concentrated. Often times it is considered the center of business. Cost of living is the highest here, as is the magnitude of activity. Today we may refer to this as the 'downtown' of a city, or the 'hub' or the 'heart'.  Examples in antiquity are the Agora in Athens or the Roman Forum, and  Central London in the modern. Cities can have one core or several,  depending on many different factors.

So now that we have an idea of what a core is, lets look at these models!

In this first model, the city is organized in a series of rings emitting concentrically outwards from the Core. As you can see above, that core of the city makes up the entire first ring, followed by (2) a ring of industry & factories, (3) a zone of transition intermixing working class housing & industry, (4) working–class residences, (4) middle–class residences, and (5) the commuter zone. When applied generally, you can see this either in play or in the past in many American and European cities.

In real-time practice, these zones would encroach somewhat on each  other, and would need to respond to any cultural influences and demands  made by the terrain. As with all models, it needs a reasonable transportation network (good roads, trains, etc). However, in a Concentric Zone Model, most  often the transit system is expensive and use is thus limited to the  wealthy.