Land-use Zoning & FAR Allocation

Every plan rests on two maps that look similar and mean opposite things. The Existing Land Use (ELU) map records what the land is actually used for right now - captured by survey, messy and mixed, the way a city really grew. The Proposed Land Use (PLU) map states what the plan intends each area to become over its horizon - tidier, zoned, aspirational.

The gap between them is the plan's real content. Where ELU shows scattered workshops in a residential fabric and PLU shows a clean residential zone, the plan is signalling an intent to phase those uses out. Comparing the two - literally overlaying them and measuring the change - is one of the most useful things GIS does for planning, and it is impossible with paper.

Zoning divides the city into areas where only certain uses are permitted - residential, commercial, industrial, public and semi-public, recreational, transport. URDPFI defines a standard set of categories precisely so that a land-use map from one city can be read in another. In GIS each zone is a polygon, and its category is a single attribute value - use = R for residential, C for commercial, and so on.

Because the category is an attribute, the plan becomes queryable: select every commercial polygon within 200 m of a metro station; total the industrial area proposed inside the municipal boundary; find residential zones that abut heavy industry. The colour on the map is only a rendering of that attribute; the attribute is the thing you can actually reason with.

Zoning alone would let a residential zone hold a bungalow or a tower - so plans attach a density control. The Floor Area Ratio (FAR), called Floor Space Index (FSI) in many Indian states, is the ratio of a building's total floor area to its plot area. A plot of 1,000 m2 with a FAR of 1.5 may build 1,500 m2 of floor space, however it is stacked. It is the single most powerful number in Indian development control, because it converts directly into how many people and how much built form a piece of land will carry.

FAR and FSI mean the same ratio; the label differs by state, and the rules for what counts (basements, balconies, common areas) differ too - which is why a raw FAR number is only meaningful alongside its state's Development Control Regulations. On GIS, FAR sits as a numeric attribute on each zone or plot, so buildable floor space is a field calculation away.

In a well-built plan geo-database, every zone polygon carries both attributes - use and far - and often a permitted-height and ground-coverage rule beside them. That lets a planner test capacity directly: multiply each residential polygon's area by its FAR to estimate proposed floor space, divide by an assumed dwelling size to estimate dwelling capacity, and compare against population targets.

This is where GIS earns its place over a spreadsheet. The areas come from the geometry (measured, not typed), the FAR from the zone, and the join is automatic. Change a zone's FAR and the capacity estimate updates. That is scenario testing - the core of tools like ArcGIS Urban, and entirely reproducible in free software with a field calculator and a pivot.

Land-use maps are simplifications, and their weaknesses are predictable. The single-category model struggles with genuine mixed use - the ubiquitous Indian building that is shop, workshop and home at once - and often records only the dominant use, hiding the rest. ELU surveys have a positional and temporal error: they are as accurate as their scale and as current as their survey date. FAR figures on a map are the permitted ceiling, not the built reality, and the definition of countable area shifts between states and even amendments.

So compute capacity as a scenario, not a prophecy. State your assumptions - dwelling size, achievable FAR, vacancy - and treat the output as a defensible estimate whose inputs anyone can inspect.