Let’s Build an Open Zoning Data Standard

Zoning – unsexy, unglamorous zoning – is likely the most important tool that government agencies and urban planners have in their arsenal to shape the urban environment. For those blissfully unaware of zoning’s existence – it’s the mechanism by which almost all US cities (with one notable exception) regulate what you can or can’t do with your property. Typical zoning regulations include things like land use (residential, commercial, industrial, etc), a measure of density called Floor Area Ratio (or FAR, shown in the map below), and design regulations like height limits and setback requirements that determine the position of a building on a lot. Things can – and do – get more complicated than this, but these are the essentials of zoning that have been in place since the early 20th century.

Zoning Allowed Density and Transit Stations in Chicago

Zoning Allowed Density and Transit Stations in Chicago

Zoning regulations are not static – in principle, they’re designed to change to reflect a city’s vision of future development, making them one tool by which master planning principles are applied in practice. Changing zoning codes to allow for higher densities in areas that are well served by public transport is, for example, a critical element of the concept of Transit-Oriented Development (or TOD).

Zoning is powerful tool, but one that’s rarely discussed in detail except by planners, city officials, or those who suddenly realize that the zoning code affects what they can do with their property. Given how critical zoning is to the future of our cities, this conversation deserves to be broader and more inclusive.

Part of the reason for a lack of interest in zoning is the difficulty in actually visualizing and understanding your zoning code. The traditional way to share the zoning code is in static maps or, more recently, data portals that often suffer from all the challenges described here. Neither of these tools are particularly easy, user friendly, or inviting.

Luckily more cities are doing better and opening up their zoning data in geospatial formats for bulk download. I’ve listed the cities I’ve found that do this in Chicago, Washington, DC and New York at the Civic Commons wiki. This is a great step – and I hope more cities are already following or will in the near future (please add to this list if you know of any).

But simply providing the zoning district geospatial data is only half the battle. Actually interpreting what’s in the zoning code – how individual zones regulate the nature of what, where, and how much you can build – is just as critical, and generally more complicated. To get a sense of this – block out an afternoon and read through a typical zoning code (just kidding). What’s needed is a simplified key to decipher the zoning code and breakdown its key elements. In the most basic terms, what we need is a lookup table to link the spatial map of zoning districts to their most critical regulatory elements – permitted land use, density, setbacks, etc. This is exactly what the folks at Open City Apps in Chicago did with Second City Zoning, a project designed to make zoning understandable to the average SimCity player. You can see the simplified zoning district table they created here.

Their zoning district table is fantastic – and their hard work deciphering the data is what allowed me to create quick mashup map from their data to show zoning density near transit. What we need now is to start moving beyond deciphering the individual zoning codes of a given city to building a way to share zoning data in an easily sharable, standardized format. We’ve already seen the power of the open data standard for public transit that I’ve written about before, GTFS. GTFS has in fact been so successful that it’s becoming shorthand for ‘good data standard’ in the broader sense, as evidenced by a recent tweet from Mark Headd, chief data officer for the City of Philadelphia.

So why build an open zoning data standard? A zoning data standard would allow for zoning visualization apps, like those developed for NYC, to be used across jurisdictions. In cities that sprawl across zoning jurisdictions (or even states, as in DC), a zoning standard would allow for an easy analysis and comparison of how, for example, different cities in the DC metro area are supporting transit oriented development. More broadly, standardizing the way zoning data is shared would allow for it to be mashed up and analyzed with things like public transport accessibility analyses like those for NYC done here, possibly providing an analytical input to the way zoning densities are ultimately set.

So what would an open zoning data standard look like? Unfortunately, zoning data is a fair bit more complicated than transit schedule data. Every city defines land use categories with some local idiosyncrasies built in. In addition, things like density controls can actually be limited through overlapping regulations on setbacks, minimum lot size per dwelling unit, height, etc – and which one of these governs may well vary from individual lot to individual lot. In addition, ‘overlay’ zones are increasingly used by cities to supercede an existing zone and allow for different uses and densities, including in DC. So a zoning standard would need a way to not only communicate information, but a method for interpreting the end result of the different rules and processes in a given zone. More broadly, zoning is an evolving practice, and while what I’m describing is principally the Euclidean type of zoning codified in the 1920s, new forms of zoning that focus on form, performance, and other metrics have started to emerge.

It’ll be complicated, but I don’t know any better way to do this than to start. I’ve laid out a simple table for DC’s zoning code, and by the end of tomorrow’s Open Data Day event in DC I’d like to be able to make a map like this for DC. I’ll be at Open Data Day tomorrow in DC (check the projects list) working on the specifics of DC but eager to talk to anyone interested in the broader issue of open zoning data standards. Should be fun.


5 thoughts on “Let’s Build an Open Zoning Data Standard

  1. Pingback: Legal Informatics Project Featured at Open Data Day DC 2013 | Legal Informatics Blog

  2. Pingback: Open Data Day versus legal codes | bureauphile

  3. Pingback: Open Data Day Recap | Zero expectations

  4. Pingback: Zoning, Open Data and Destiny | Civic Innovations

  5. Pingback: Zillow Reading List, November 6th - Zillow Research

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