Blog Archives

The impact of street network connectivity on pedestrian volume

This paper investigates the impact of street network connectivity on pedestrian volume. Street
network connectivity measured in most current studies captures only the metric characteristics
of streets or physical connectivity. A whole different type of connectivity, visual connectivity, is
largely ignored. Described in basic terms, higher physical connectivity means shorter travel time
to reach the same number of destinations while higher visual connectivity means fewer turns to
see the same number of destinations. Despite the correlation of these two connectivity constructs, studying both physical and visual connectivity is essential to better understand the role of
street network on pedestrian activity. Using pedestrian counts of 302 street segments in Buffalo,
New York, structural equation modelling highlights the multiple relationships between street network connectivity, built environment characteristics, and pedestrian volumes. Our findings
suggest that both the conventional metric-based measure of physical connectivity and geometric based measure of visual connectivity have significant positive impacts on pedestrian volumes,
together with job density and land use mix. This outcome can encourage practitioners to pay
attention to both the geometry of street network and its metric characteristics in order to create
a pedestrian-friendly environment.

Park design and children’s active play: a microscale spatial analysis of intensity of play in Olmsted’s Delaware Park

This paper offers a microscale exploration of the role of park design on the intensity of physical activity among youth. The actual, unstructured use of a park—specifically, Delaware Park, an Olmsted-designed park in Buffalo, New York—by ninety-four children was observed and analyzed objectively using geographic information systems, global positioning systems, and accelerometers. Data were analyzed at the scale of 25 ft × 25 ft cells overlaid as a grid on the entire park. Results from the regression analysis show that particular features of parks—especially complexity in landscape surfaces, proximity to sport facilities and playgrounds, and the availability of pedestrian trails—enable greater intensity of youth physical activity in a park.

Municipal property acquisition patterns in a shrinking city: Evidence for the persistence of an urban growth paradigm in Buffalo, NY


The purpose of this article is to examine municipal property acquisition patterns in shrinking cities. We use data from the City of Buffalo’s municipal property auction records to analyze the spatial distribution of properties offered for sale in its annual tax foreclosure auction. In addition to these data, we examine demolition and building permit records. Our analysis suggests that cities like Buffalo follow strategies based on an urban growth paradigm when responding to abandonment. This paradigm operates under the assumption that growth is a constant and urban development is only limited by fiscal constraints, underdeveloped systems of urban governance, environmental degradation, and resistance by anti-growth coalitions. We recommend that planners in shrinking cities de-emphasize growth-based planning and focus on rightsizing strategies. These strategies are based on the assumption that growth is not a constant. Consequently, urban revitalization is concentrated in a smaller urban footprint.

Neighborhood Parks and Reduction in Stress among Adolescents: Results from Buffalo, New York


Planners and landscape architects have long recognized the critical role of green space in urban environments. This cross-sectional field study of 68 adolescents determined the association between percent neighborhood park area and perceived stress among adolescents, while controlling for physical activity. This study is the first to examine this association using objective measures of park area and adolescents physical activity. A multivariate regression model indicated that percentage of park area (β = -62.573, p < 0.03) predicts perceived stress among adolescents. Access to neighborhood parks buffers adolescents against perceived stress after controlling for socio-economic status and physical activity. Policy recommendations for incorporating parks into neighborhood design are given.

‘Big Data’ for Pedestrian Volume: Exploring the use of Google Street View Images for Pedestrian Counts

New sources of data such as ‘big data’ and computational analytics have stimulated innovative pedestrian oriented research. Current studies, however, are still limited and subjective with regard to the use of Google Street View and other online sources for environment audits or pedestrian counts because of the manual information extraction and compilation, especially for large areas. This study aims to provide future research an alternative method to conduct large scale data collection more consistently and objectively on pedestrian counts and possibly for environment audits and stimulate discussion of the use of ‘big data’ and recent computational advances for planning and design. We explore and report information needed to automatically download and assemble Google Street View images, as well as other image parameters for a wide range of analysis and visualization, and explore extracting pedestrian count data based on these images using machine vision and learning technology. The reliability tests results based on pedestrian information collected from over 200 street segments in Buffalo, NY, Washington, D.C., and Boston, MA respectively suggested that the image detection method used in this study are capable of determining the presence of pedestrian with a reasonable level of accuracy. The limitation and potential improvement of the proposed method is also discussed.

Creating sustainable urban built environments: An application of hedonic house price models in Wuhan, China


Due to rapid urbanization, auto-mobility, and industrialization, the increasing desire to protect environments and satisfy residents has led to an emphasis on the creation of sustainable urban environments in China. This paper is an empirical study using hedonic price models to examine a comprehensive set of environmental sustainability elements including green space, transit systems, and central business districts (CBDs) and compare their relative importance in Wuhan, China. The results show that among all housing characteristics, environmental sustainability elements had the greatest impacts on house prices. Natural water resources have the most significant positive effects on property values when they are integrated with cultural, tourism, and commercial resources to form natural recreation clusters or areas. Also, home buyers are willing to pay more for housing clusters or subdivisions with proximity to CBDs. In addition, the significant negative effects of light rail on house prices within a 1-mile radius indicate that it has not become an attractive amenity to home buyers, due to combined effects of other neighborhood amenities, little land use diversity, and the fare system. These results have implications for local and regional governments in setting priorities for sustainable development.

Mapping Urban Impervious Surface by Fusing Optical and SAR data Based on the Random Forests and D-S Theory

The proliferation of impervious surfaces results in a series of environmental issues, such as the decrease of vegetated areas and the aggravation of the urban heat island effects. The mapping of impervious surface and its spatial distributions is of significance for the ecological study of urban environment. Currently, the integration of optical and synthetic aperture radar (SAR) data has shown advantages in accurately characterizing impervious surface. However, the fusion mainly occurs at the pixel and feature levels which are subject to influences of data noises and feature selections, respectively. In this paper, an innovative and effective method was developed to extract urban impervious surface by synergistically utilizing optical and SAR images at the decision level. The objective of this paper was to obtain an accurate urban impervious surface map based on the random forest classifier and the evidence theory and to provide a detailed uncertainty analysis accompanying the fused impervious surface maps. In this study, both the GaoFen (GF-1) and Sentinel-1A imagery were first used as independent data sources for mapping urban impervious surfaces. Then additional spectral features and texture features were extracted and integrated with the original GF-1 and Sentinel-1A images in generating impervious surfaces. Finally, based on the Dempster-Shafer (D-S) theory, impervious surfaces were produced by fusing the previously estimated impervious surfaces from different datasets at the decision level. Results showed that impervious surfaces estimated from the combined use of original images and features yielded a higher accuracy than those from the original optical or SAR data. Further validations suggested that optical data was better than SAR data in separating impervious surfaces from non-impervious surfaces. The fused impervious surfaces at the decision level had a higher overall accuracy than those produced independently by optical or SAR data. It was also highlighted that the fusion of GF-1 and Sentinel-1A images reduced the amount of confusions among the low reflectance of impervious surface and water, as well as for low reflectance of bare land. An overall accuracy of 95.33% was achieved for extracting urban impervious surfaces by fused datasets. The spatial distributions of uncertainties provided by the evidence theory displayed a confidence level of at least 75% for the impervious surfaces derived from the fused datasets.

Neighborhood for Playing: Using GPS, GIS, and Accelerometry to Delineate Areas within which Youth are Physically Active


Despite the documented importance of the neighbourhood environment on youth physical activity, little empirical research exists regarding the geographical boundaries of neighbourhoods within which youth are physically active around their homes. Studies and public policies often arbitrarily assume the extent of these boundaries, which vary from study to study. This paper combines GPS data, diaries and accelerometry to delineate empirically the local area and distance within which youth play in Erie County, New York. The study found that youth tend to be physically active within a quarter-mile radius around their homes and to focus on one section of the often assumed circled neighbourhood.

Assessing Walkability in the City of Buffalo: Application of Agent-Based Simulation


Significant research has been conducted on how environmental attributes influence people’s decisions to walk. In much of this
research, however, environmental attributes are averaged for neighborhoods or census geographies for sampled populations. Moreover, the
effect of an agent’s walking choices on other actors is not adequately represented by either objective or perceived measures in the literature.
Macro-level patterns of walkability arise from interactions across actors and urban environments. The agent-based approach allows for
modeling individual uses of the environment by treating the populations as objects that can interact with the environment and other people.
This study builds on previous research on pedestrian movement and geographic information system (GIS) measures of the built environment
using the agent-based approach to explore the dynamics of the built environment and people’s decision-making processes concerning walking. The results show that models that take individual perspective into account and include social interaction can better capture characteristics
of the built and social environment that influence people’s walking choices. This method lays out a new framework for assessing macro-level
patterns of walkability across a city using micro-level data.

Street Level Urban Design Qualities for Walkability: Combining 2D and 3D GIS Measures

Much of the physical activity and built environment literature has focused on composite walkability indices based on the D variables– design, density, diversity, destination accessibility, and distance to transit. This literature, however, has largely ignored the microscale streetscape features that affect the pedestrian experience. Five street level urban design qualities were recently identified and defined for quantitative measures although these  measures are mostly through subjective field observation. View related features such as long sight line and proportion of sky have not yet been objectively measured due to the limitation of data and method. This study uses both 2D and 3D GIS to objectively measure street level urban design qualities in Buffalo, New York and tests their correlation with observed pedestrian counts and Walk Scores. Our results showed that 3D GIS helped to generate objective measures on view related features. These objective measures can help us better understand the influence of street level urban design features on walkability for designing and planning healthy cities.