Issue link: https://read.dmtmag.com/i/117518
Historical Mapping A detailed historical zoning map shows updated zoning outlined by dots. zoning districts that allow certain commercial uses to occur—picture a street with commercial storefronts on the ground floor and residential space above. Special-purpose districts are areas where unique sets of zoning regulations are created to accommodate special localized conditions or characteristics. Because the data were maintained in an enterprise GIS, there already was a limited "time-travel" capability using database archiving, which preserves a running record of changes made to the stored data as auxiliary tables. Archiving allows users to "roll back" data to any past state or, to put it in time-travel terms, to any time A busy zoning map contains examples of zoning, commercial-overlay and special-purpose districts. 16 G E O W O R L D / M A R C H 2 O 1 3 and location between the present and the beginning of time (of the database, not the universe). Historical reference markers created in the database flagged every zoning change with the date it was adopted. So if a planner wanted to view the zoning at some point in the past, he or she just needed to select the date of the nearest historical marker to display the zoning state at that time. This allows planners to revisit the previous states of entire areas that had been rezoned directly in GIS software instead of having to reference old sets of map sheets. Further, the availability of this historical information as GIS data makes it infinitely more useful to city planners than simple scans of hardcopy maps that would need to be patched together to get the whole picture. "Planners often need to research the history of a site, including its past zoning," says Steven Lenard, a senior planner with the Department of City Planning's Brooklyn Office. "Previous zoning helps determine the rationale for past development projects and the legal status of current structures. Having all the zoning districts ever mapped in the city in one database [would allow] for independent research on how zoning has been used to influence developments and, more interestingly, allows researchers to test theories about what influences zoning." After people learn that they can acquire continuous historical GIS zoning data back to 2007, the first thing likely to be heard isn't how great this is. Instead, they invariably will ask, "What about zoning before 2007?" Therefore, creating a complete GIS archive of zoning going back to the original 1961 zoning was a project waiting to happen. By 2011, a combination of factors came together to finally get this project moving. The zoning GIS dataset had reached a level of maturity where it was accepted by staff as an accurate representation of zoning and used widely by city planners. At the same time, planners were becoming more sophisticated in their use of GIS and their demand for new data sources. Second, in the process of developing the presentday zoning dataset, a reliable workflow procedure had been established that made extensive use of interns to support such labor-intensive data-creation projects. The department has an active summer-internship program that attracts students from all over the United States and abroad. Many of them are looking to gain practical GIS experience beyond what's typically taught in introductory college courses. "It was a great opportunity for me to be part of this exciting project," adds Zhenqi Lu, a recent master's degree graduate of Clark University's GIS program. "This was my first experience in GIS work outside of academia. The work built upon what I learned in school, while giving me a vision of how GIS technology is applied in urban planning." A natural synergy emerged, and these interns were employed to create zoning GIS data. So there was