Research evaluating the impacts of smart growth, new urbanism, and pedestrian oriented design on transportation, public health and community life is limited by weaknesses of conventional urban form measures. A review of recent literature finds standard measures, such as development density and land use, do not sufficiently differentiate basic elements of neighborhood form. This contributes to ambiguous research findings. Improved methods for operationalizing urban form as an independent variable is a critical need for the emerging field of urban design.
This dissertation explores the potential of developing simple, replicable measures that can better distinguish first order differences between neighborhoods. The complex nature of three dimensional space and a lack of useable datasets at this scale suggested an exploratory, hypothesis generating, research approach. The project is built around detailed study of a dozen neighborhoods in the Upper Valley Region of Vermont and New Hampshire. An extensive field based analysis of urban form identified key urban form variables and speculated on associations with perceived qualities of the neighborhood environment. Based on those findings, a GIS based, parcel-level data set was compiled at two scales of analysis neighborhood-wide and the more detailed realm of the street, block, lot, and building. The database was the basis for exploratory derivation and testing of simple replicable measures of neighborhood form. A field based survey tour established a perceptual baseline for a series of environmental qualities across the case studies. Correlating mean survey scores with calculated values served as a basic validity test for experimental measures.
Initial findings suggest both substantial limitations and promising areas of research related to developing quantitative measures of city form. The complexity of the built environment limited successful measures to very simple constructions based on the standard density measure of units per acre such as parcels per acre, buildings per parcel, or simple ratios such as building height to setback. Correlations of measured and perceived values offered insights into the relationship between urban form and environmental qualities. For qualities such as density, connectivity, and enclosure, the associated physical dimensions were generally clear and relatively easy to measure. Physical relationships associated with other qualities such as grain, scale, consistency and permeability, are more complex but certain classes of measures seemed to capture much of the observed variation between cases. Others, such as variability, are so complex that they seem best approached, at least initially, through use of proxy measures. Opportunities for future research include testing measures across a broader context of urban form and density and operationalizing measurement protocols within a GIS framework.