Controlling sprawling patterns has long been a focus for planners. The growth of cities brings an added pressure to develop more land, at the risk of losing important agricultural and environmental areas within a region. Some cities across the United States have enacted transfer of development rights (TDR) programs, which attempt to preserve current land uses by allowing landowners to sell development rights that can be transferred to other locations. Under TDR programs, parcels within the area trying to be preserved are called "sending areas."
Evaluating TDR Program Effectiveness With Evidence
How successful are TDR programs at long-term land preservation and what approaches should planners consider when comparing program effectiveness? In "Land Preservation Under the Transfer of Development Rights Program," (Journal of the American Planning Association, Vol. 87, No. 2), author Li Fang attempts to answer this question by tracking land use within the sending areas of Montgomery County, Maryland. Montgomery County's TDR program is a national model when it comes to perceived TDR success. Fang speculates that if the Montgomery County TDR Program is unable to encourage concentrated, high-density development, then TDR programs across the United States may need to be reevaluated.
Fang mapped land use in Montgomery County concerning development rights transactions. By categorizing TDR transactions into two time periods (1973–2002, 2002–2010), Fang examined the contiguity of preserved land. The study found that even in a county with a highly regarded TDR program, there is evidence of undesirable development patterns. The scattered development seen in Montgomery could be a larger indication that TDR-sending areas are unable to fend off the pressures for low-density, residential uses when landowners retain some or all the development rights. Land parcels that terminated all their development rights were better at preserving contiguous land than those land parcels that retained some or all their development rights.
Figure 3. Urban land expansion in the transfer of development rights sending area.
TDRs and Land Use Patterns
The connections made between TDR transactions and resulting land pattern use make this work extremely valuable for urban planning discussions around smart growth. Fang introduces a consideration for planners when dealing with TDRs and proposes that one cannot truly measure the outcome of TDR effectively without also considering how development patterns evolve. Instead, encouraging desirable patterns should be a part of consideration in designing land preservation programs, through policy tools such as "tighten[ed] zoning" for contiguous land or "encourage cluster building" in the design of a TDR program.
While this study is limited to the findings of Montgomery County and may not necessarily reflect the nuanced situations for counties across the country, the author provides a strong case for adjusting the standard practices around TDR program evaluations, which should factor in land use and development changes.
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About the author
Mike Lidwin is a Master in Urban Planning candidate at Harvard University.