Urban Planning: Plots, Buildings, and Regulations
Introduction: Public and Private Spaces in Urban Planning
The space defined by roads and buildings is essential for urban planning, encompassing both public and private areas. Roads, belonging to municipalities, are considered public spaces, while the areas designated for buildings are private. Developers often bear the initial costs of road construction, which are then handed over to the municipality. A city block can contain multiple buildings arranged in various ways, with interior spaces serving different purposes. This block becomes the fundamental unit for urban planning and management.
The Plot: A Fundamental Unit of Urban Land
The privatization of urban space necessitates dividing blocks into smaller units called plots. Each building occupies a plot owned by one or more individuals. The building and plot are intrinsically linked and registered as a single entity in real estate records. A plot is defined as any enclosed area of land, characterized by its boundaries, which are the lines separating it from adjacent parcels. It is essentially defined by its surface area and delimitation.
Urban Growth and Rights of Way
Urban growth involves occupying new land. The concept of right of way is crucial, referring to a path across private property that also serves as a public road. This often occurs in areas traversed by public roads. Historically, many plots were used for agriculture. As cities expanded, these agricultural plots were converted into urban land through agreements. These plots could be combined (aggregated) or divided (segregated). Existing roads were transformed into streets, often respecting the original plot divisions. Initially, animal-powered transportation allowed for ample space between blocks. However, the advent of motorized transport led to wider roads to accommodate vehicles and access to parcels.
Modifying land for new urban areas requires agreements between landowners, subject to municipal approval.
The Plot as an Elemental Urban Unit
Several parameters define a plot:
- Regularity and irregularity
- Extension or surface area
- Dimensions of its boundaries
The plot’s surface area is the horizontal projection of the area within its boundaries.
Planning Regulations for Plots
Planning regulations often stipulate conditions for plots:
- Minimum or maximum plot sizes suitable for building
- Determination of the maximum and minimum frontage
Every plot must have a boundary facing a pathway for access, known as the front or front edge. The other boundaries are called lateral boundaries, and the boundary opposite the front edge is the rear or back. Planning standards establish minimum and maximum dimensions for these boundaries.
Building on the Land: Position and Occupation
While building placement on a plot is often free, planning regulations frequently impose limitations based on parameters such as planimetric references, altimetric references, the building’s height, and its relationship to other buildings.
Planimetric References
These can be summarized as:
- Boundaries
- External alignment or building line: This line, established by urban planning, separates land intended for roads or public spaces from private plots designated for building. It usually coincides with the front boundary, separating public and private space.
- Internal alignment or setback line: This line demarcates the buildable area within the plot from the required open space. It indicates the minimum distance the building must be set back from the external alignment. This alignment is also known as the buildable background.
Altimetric References
The most important altimetric reference is the concept of grade, which represents the longitudinal profile of the public road. It’s a crucial reference point for determining whether a building is below or above ground level. It also influences the depth of urban services running beneath public roads. Benchmarks set by the grade serve as a basis for measuring the building’s height (usually maximum).