High-density Neighborhoods Research Articles

The impact of urban residential development patterns on forest carbon density: An integration of LiDAR, aerial photography and field mensuration

Urban development continues to reshape forest landscapes and influence the carbon storage capacity of trees. To date, the impact of urban patterns on forest carbon density remains to be systematically evaluated. A major challenge is the lack of accurate and spatially explicit estimates of forest carbon storage over the entire urbanized area. In this study, we first developed an integrated approach that synergizes remote sensing LiDAR (light detection and ranging) and aerial photography to efficiently model landscape-level forest carbon storage in an urban environment at a fine resolution of 20m. Using a case study in the Charlotte Metropolitan Region, USA, we were able to determine the total amount of carbon stored in the local forests to be 3.8 million tonnes ($298 million value), with an average carbon density of 53.6t/ha. We further applied statistical analysis to investigate the relationship between urban developed patterns (i.e., landscape metrics) and forest carbon density in four types of residential neighborhoods (categorized by percent built-up ranging from low, medium-low, medium-high to high density). Results indicate a decrease of forest carbon density with an increase of carbon variance in neighborhoods where the intensity of development became higher. Residential neighborhoods with a higher built-up density were more likely to be affected by a larger number of landscape metrics. This indicates that a proper design of the neighborhood level urban spatial patterns (especially in high density neighborhoods) is essential to maximizing forest carbon storage at the landscape level.

An examination of recent trends in multimodal travel behavior among American motorists

ABSTRACTAccording to national statistics, 87% of all trips in the United States are by automobile and 90% of commuters typically get to work by car. Statistics for individual trips or the main mode of commuting do not capture variability in individual travel behavior over time. This article uses the 2001 and 2009 National Household Travel Surveys to analyze recent trends in the share of multimodal motorists who use a car and also walk, bicycle, or ride public transport during a day or week. This article identifies trends of multimodal behavior among car users in the United States and provides profiles of these multimodal motorists.During a typical day about 14% of American car users make at least two trips by foot, bicycle, or public transport, while during a typical week about 25% of motorists make at least seven trips by means of transport other than the car. Results from a bivariate analysis and logistic regressions suggest significant shifts toward more multimodal behavior among motorists between 2001 and 2009. Multimodal motorists tend to be younger, educated beyond high school, in households without cars, and live in high-density neighborhoods with access to a rail system. Results suggest that planning for walking, cycling, and public transport benefits a larger proportion of the U.S. population than suggested by traditional trip-based analysis.

Travel Distances in Daily Travel and Long-Distance Travel: What Role is Played by Urban Form?

There is a lot of research on spatial differences in travel behaviour, specifically on travel distances. This research suggests that the distances travelled by the inhabitants of municipalities with lower population and neighbourhoods with lower density and less mixed land use are longer than those travelled by the inhabitants of cities with higher population, high density, and greater mixed land use. However, related studies focus mainly on daily travel. In this paper we study travel distances in daily trips based on random day trip diaries and long-distance trips for private and business purposes based on retrospective questions in the same questionnaire, asking about “longer journeys with overnight stay” within three months of the survey. We use Heckman models and ordinary least squares regressions to study the effects of municipality size classes based on population, population density, and land-use mix, while controlling for sociodemographics. We find distances travelled on long-distance trips and daily trips to be affected by sociodemographics in much the same way, while spatial effects affect distances travelled on daily and long-distance trips mostly in different directions. Residents of small municipalities and low-density neighbourhoods make fewer and/or shorter long-distance journeys than those living in large cities and high-density neighbourhoods, but the latter travel shorter distances in their daily lives.

Compact Development without Transit: Life-Cycle GHG Emissions from Four Variations of Residential Density in Vancouver

Numerous studies have shown that compact, mixed-use, transit-oriented developments contribute to reduced use of automobiles and in turn contribute to lower greenhouse gas emissions. When everyday destinations are within walking distance, people are more likely to walk or cycle, and if transit is within walking distance people are more likely to use it. Other studies have shown that compact development enables reductions in building energy consumption that contribute further to emissions savings. The reduced emissions are assumed to rely on the combination of compactness and transit connectedness. However, this combination requires an extensive transit network covering large areas both of residential and of employment destinations. Such networks often do not exist and are too costly to construct. When they do exist, the transit networks often do not reach those outlying neighbourhoods with the greatest potential for future growth and densification. This paper therefore asks what emissions savings compact development can achieve in the absence of high-frequency transit. In an examinination of the life-cycle emissions of four variations of density in three different neighbourhoods in Vancouver, none of which is well served by transit, we found a wide range of emissions profiles. A mixed-use new urbanist development produced 22% fewer emissions than an adjacent development of large single-family homes, both of which were in a transit-poor area on the far edge of a suburban city. A high-density neighbourhood adjacent to a suburban city centre, and one adjacent to a central city centre, produced 50% and 67% fewer emissions than the neighbourhood of large single-family homes. Findings suggest that, while compactness may be most effective when it is coupled with high frequency transit, decoupling the pair and building compactness before or without transit can still yield considerable household emissions reductions.

Solar optimized residential neighborhoods: Evaluation and design methodology

The paper investigates the key design parameters of two-story residential units and neighborhood patterns for increased solar potential. The investigation aims at exploring flexibility of design and maintaining functionality of the dwellings, while promoting energy conservation, and maximizing solar capture and utilization by façades and roofs. Building shapes include convex shapes (rectangle) and non-convex shapes consisting of potentially mutually shading wings, such as L and U shapes. Site layouts incorporating straight and curved road (e.g. cul-de-sac) are investigated.The main considerations in the design of a convex building shape are aspect ratio and orientation relative to south (in the northern hemisphere). For non-convex shapes the primary additional parameters that should be taken into consideration are: depth ratio–ratio of shading to shaded façade widths, number of shading façades (wings), and the angle enclosed by the wings. For high density neighborhoods, attached units can reduce heating and cooling energy consumption while maximizing roof surface for integration of solar collectors. In neighborhoods featuring configurations of parallel rows of dwelling units, the distance between rows is of primary importance. A distance of at least 85% of the minimal distance required to avoid shading between the rows is recommended to minimize shading effects.Design guidelines and methodology for the design of solar optimized neighborhoods located in northern mid-latitudes are proposed, based on the effects of design parameters on energy performance. The proposed methodology involves selection among design alternatives by means of an evaluation procedure based on weighted performance criteria.

Childhood drowning in Georgia: A geographic information system analysis

Drowning is one of the major causes of childhood mortality from unintentional injury in the United States. This study aims to delineate the drowning hot spots by aquatic environment and to examine the socioeconomic characteristics of neighborhoods with high densities. Drowning death records (2002–2008) among children aged 0–17 were obtained from the Office of the Child Advocate in Georgia. Drowning victims are initially analyzed by race, gender, age, aquatic environment, use of a personal floatation device, and the security of a pool. Using kernel density estimation and LISA statistics, this paper delineates drowning clusters by density and rate respectively. High-density neighborhoods are then investigated using a variety of socioeconomic factors by multiple-comparison test, Ordinary Least Squares (OLS) regression, and Geographically Weighted Regression (GWR). The result shows that the majority of victims were white, male, and children aged 0–4. Private swimming pools and open water were two leading drowning places. Blacks were more likely to drown in public swimming pools and in children aged 5–14 than white counterparts. Private swimming pools and children aged 0–4 have seen more white victims than blacks. Substantial spatial variation in drowning density and rate is present in Georgia. High-density drowning neighborhoods had a significantly lower rank of median income (p < 0.01) and lower rank of educational attainment in their counties than the low-density group. The GWR results suggest such associations vary in space. This study highlights the role of different socioeconomic factors in the interconnections of drowning risk factors. Findings suggest that health policies and prevention campaigns may be customized based on specific aquatic types and risk factors in different local communities.

Habitat quality and population density drive occupancy dynamics of snowshoe hare in variegated landscapes

The influence of habitat quality and population density on occupancy dynamics may surpass that of traditional metrics of area and isolation, but often this is not considered explicitly in studies of spatially structured populations. In landscapes that are not easily characterized as binary habitat/non‐habitat (e.g. variegated landscapes), this influence may be even more important and occur at both local and landscape levels. It follows that occupancy dynamics may be driven by disparate processes depending on how extinction or colonization relate to habitat quality and population density. We examined the relative influence of area, structural isolation, habitat quality, local population density, and neighborhood population density (i.e. population density in the landscape around a site) on the probability of extinction and colonization of snowshoe hare Lepus americanus across an expansive forest mosaic landscape (encompassing the northern third of Idaho). Habitat quality and population density were highly influential in determining extinction and colonization, whereas patch area and isolation were much less important. Sites with heavier vegetative cover at the site or landscape‐level were more likely to be colonized and less likely to go extinct, and sites with greater local population density in the previous time step had lower probability of extinction. Sites embedded in high density neighborhoods also were less likely to go extinct, but not more likely to be colonized. We found a significant interaction between local and neighborhood population density on extinction in 1 yr, suggesting that the strength of demographic rescue may vary dependent on local site densities. Our results add to a growing literature showing that factors outside of structural metrics of area and isolation are important drivers of occupancy dynamics. Given the multi‐scaled influence of habitat quality and population density on occupancy dynamics, our work also indicates that research on snowshoe hare must extend beyond simply assessing local factors to understand the spatial dynamics of populations.

Breeding bird density does not drive vocal individuality

Abstract Many species produce individually specific vocalizations and sociality is a hypothesized driver of such individuality. Previous studies of how social variation influenced individuality focused on colonial or non-colonial avian species, and how social group size influenced individuality in sciurid rodents. Since sociality is an important driver of individuality, we expected that bird species that defend nesting territories in higher density neighborhoods should have more individually-distinctive calls than those that defend nesting territories in lower-density neighborhoods. We used Beecher’s information statistic to quantify individuality, and we examined the relationship between bird density (calculated with point-counts) and vocal individuality on seven species of passerines. We found non-significant relationships between breeding bird density and vocal individuality whether regressions were fitted on species values, or on phylogenetically-independent contrast values. From these results, we infer that while individuality may be explained by social factors, breeding bird density is unlikely to be generally important in driving the evolution of individually-specific vocalizations.

Neighborhood environment and walking for transport and recreation in Central European older adults

Background: Neighborhood environment is an aspect that influences physical activity, mainly walking. Hence, built environment research may help to use environmental and policy strategies to increase physical activity. Objective: This cross-sectional study aimed to investigate the association between perceived neighborhood environment and meeting the recommendation of at least 30 minutes of walking 5 or more days a week within active transportation and leisure-time domains in Central European older adults. Methods: Four hundred and fifty six healthy ambulatory older adults filled out the modified and culturally adapted version of the Neighborhood Environment Walkability Scale (ANEWS) for obtaining perceived environment information and the self-administrative long version of the International Physical Activity Questionnaire (IPAQ) for assessing physical activity levels. Results: Respondents living in high residential density neighborhoods (OR 1.87), living in flats (OR 2.09) and in location with &le;100,000 inhabitants (OR 1.63) were more likely to meet recommendation within walking for transportation. Owning a dog was associated with meeting recommendation within walking for leisure (OR 1.69). Conclusions: This study supported the specific impact of environment on meeting PA recommendations within transportation and leisure time walking in older adults. Out of all perceived neighborhood environmental attributes received from ANEWS questionnaire, only high residential density was positively associated with meeting recommendation within total walking and walking for transport.

The use of amenities in high density neighbourhoods by older urban Australians residents

Like other major cities, Brisbane (Australia) has adopted policies to increase residential densities to meet the liveability goal of decreasing car dependence. This objective hinges on urban neighbourhoods being amenity-rich spaces, reducing the need for residents to leave their neighbourhood for everyday living. While older people are attracted to urban settings, there has been little empirical evidence linking liveability satisfaction with older people's use of urban neighbourhoods. Using a case study approach employing qualitative (diaries, in-depth interviews) and quantitative (Global Positioning Systems and Geographical Information Systems mapping) methods, this paper explores the effect of the neighbourhood environment and its influence on liveability for older urban people. Reliance on motor vehicles and issues with availability and access to local amenities inhibit local participation for older people. Highlighting these issues furthers our understanding of the landscape planning and design factors that make urban neighbourhoods more liveable for older residents.

CANNABIS AND PSYCHOSIS: IS THE ASSOCIATION MODERATED BY ENVIRONMENTAL RISK FACTORS?

Substance and alcohol misuse is a global problem that increases the risk of HIV infection. This is a concern among orphans and vulnerable children (OVC) in sub-Saharan Africa who may have elevated substance use rates. The Alcohol, Smoking, and Substance Involvement Screening Test (ASSIST) is a reliable and valid instrument of substance use among adults in primary care high-income settings. This study examined psychometric properties of the ASSIST among OVC in Zambia using Audio Computer Assisted Self-Interviewing (ACASI).Baseline data from an ongoing randomized trial of interventions to reduce HIV risk behaviors were analyzed. The analysis included 502 OVC ages 13–17 living in low-income, high-density neighborhoods in Lusaka, Zambia. Internal consistency of the ASSIST was assessed and discriminant validity was measured using items from the Youth Self Report as criterion variables.Internal reliability was strong with a Cronbach’s alpha of ≥0.80 for each of the specific substance scales and total substance involvement. For all substances except tobacco and sedatives, discriminant validity was demonstrated in distinguishing between low risk use and moderate use. Sensitivity and specificity analysis indicated adequate area under the curve across substance types (AUC range: 0.68–0.80). Discrimination between moderate and high risk was demonstrated for alcohol and total substance involvement.ASSIST administered via ACASI is a reliable instrument and an appropriate tool for distinguishing between low and hazardous substance use among adolescent OVC populations in sub-Saharan Africa. Additional examination is warranted to determine its ability to measure gradations of severity within hazardous use.

The key to sustainable urban development in UK cities? The influence of density on social sustainability

High residential density is an important element of the compact city concept alongside mixed land uses, well-connected urban layouts, and easily accessible public transport networks. However, there is little consensus on how dense ‘high-density’ residential development should be, nor on what are the impacts of such urban environments on residents. This paper attempts to address this gap in knowledge by exploring the concept of density within the context of sustainability, calling on empirical evidence conducted in the UK by the CityForm research project. This research examined the relationship between elements of urban form (including density) and sustainability. This paper specifically makes reference to the relationship between density and aspects of social sustainability, specifically social equity (i.e. access to services and facilities), environmental equity (i.e. access to and use of green/open space) and sustainability of community (including perceptions of safety, social interaction and community stability). An extensive postal questionnaire survey and series of follow-up in-depth focus groups were conducted in a number of neighbourhoods in five UK cities to examine the hypothesis that high-density neighbourhoods were less likely to support socially sustainable behaviour and attitudes than low-density ones.The paper starts with an introductory account of density in the UK to provide the context of the study. It then defines density and the aspects of social sustainability under scrutiny and discusses the claimed relationships as well as the implications that such claims have for policy and practice. The paper then reports on the empirical research findings which examine the extent to which density has any influence on residents’ propensity to engage in socially sustainable activities. The paper concludes by critically reflecting on how the findings fit more broadly into the ‘compact city’ debate in the 21st century, where urban, and not rural, environments are home to ever-increasing populations around the world.

Asymmetrical Integration: Public Finance Deprivation in China's Urbanized Villages

China's unprecedented urbanization since the 1978 economic reform has left many rural villages engulfed by expanding urban jurisdictions. Because of the collective ownership of land, these villages have not vanished over night. On the contrary, they have maneuvered to bypass planning and construction codes and rebuilt themselves into high-density neighborhoods, housing millions of migrants in the cities. This paper analyzes the continued survival of the collective economy of these villages-in-the-city ( chengzhongcun) from the perspective of public finance. Urbanized villages remain financially responsible for public services within their jurisdictions, including infrastructure, sanitation, policing, social welfare, and even education. Neither the problem of urban—rural disparities, nor the consequent lack of adequate public services has been resolved by the integration of these villages into urban areas. These villages have had to find new ways to cope with rapid population growth, finance an urbanized community, and at the same time, bear the burden of their stigmatization as a cancerous growth within otherwise ‘modern’ cities. Using the rapidly urbanized Pearl River Delta region as an empirical case, this paper explores how the urban villages are asymmetrically integrated within the cities: they contribute to the city's growth, but receive little or no public support. In contrast with the common sense that incorporation into an urban jurisdiction will bring about rising fiscal investment, in China, it is the rural villages that are financing the growth of cities.

Exploring the Influences of Density on Travel Behavior Using Propensity Score Matching

The causality issue has become one of the key questions in the debate over the relationship between the built environment and travel behavior. Since a residential self-selection effect exists, it is important to know if the observed influence of the built environment on travel behavior diminishes substantially once we control for self-selection. Using 5537 adult respondents to the 2006 Great Triangle Travel Survey in North Carolina, this study applied the propensity score matching approach to identify the causal effect of density on travel behavior and the relative contribution of self-selection to travel behavior. The results showed that, after removing self-selection bias, residents living in high-density neighborhoods travel, on average, 3.31 fewer miles per person per day than those who live in low-density neighborhoods. Self-selection effects account for 28%, 64%, and 49% of the observed influences of density on personal miles travelled, driving duration, and transit duration, respectively. We also found that different modeling approaches produce different point estimates, and that interval estimates of treatment effects tend to have a large variation. This points to a caveat of using point estimates to evaluate the impacts of the built environment on travel behavior.

An online calculator to compute phonotactic probability and neighborhood density on the basis of child corpora of spoken American English

An online calculator was developed (www.bncdnet.ku.edu/cml/info_ccc.vi) to compute phonotactic probability--the likelihood of occurrence of a sound sequence--and neighborhood density--the number of phonologically similar words--on the basis of child corpora of American English (Kolson, 1960; Moe, Hopkins, & Rush, 1982) and to compare its results to those of an adult calculator. Phonotactic probability and neighborhood density were computed for a set of 380 nouns (Fenson et al., 1993) using both the child and adult corpora. The child and adult raw values were significantly correlated. However, significant differences were detected. Specifically, child phonotactic probability was higher than adult phonotactic probability, especially for high-probability words, and child neighborhood density was lower than adult neighborhood density, especially for words with high-density neighborhoods. These differences were reduced or eliminated when relative measures (i.e., z scores) were used. Suggestions are offered regarding which values to use in future research.

Designing a Liveable Compact City: Physical Forms of City and Social Life in Urban Neighbourhoods

This paper reports findings from recent research examining the relationship between urban design and layout and aspects of social and communal life in urban neighbourhoods. To address this, six UK neighbourhoods of varying densities and layouts were selected for detailed investigation. Data on social interactions, social activities and social networks along with perceptions of the built and social environment of the neighbourhoods were collected through observations, questionnaire surveys and secondary data sources. Neighbourhood design and layout were analysed using spatial network and visibility graph analysis methods. Correlation and multiple regression tests were conducted to test the claimed associations. Findings indicate differences between socializing patterns and structure of social networks in high- and low-density areas. Low-density areas were associated with widely spread social networks and activities with very few strong relationships. In high-density neighbourhoods, respondents had small networks but stronger ties were found. Detailed investigation shows that much of this can be attributed to, among other physical factors: the location of public spaces, visibility from and to these spaces, visual links between neighbourhoods', typology and physical form of development rather than density alone. This indicates that some of the negative social impacts found within high-density urban development might be rectified with better design of neighbourhoods. It is clear that to deliver sustainable development, the compact city will have to be designed with specific spatial and built environment characteristics.

Teaching and Learning Guide for: Environmental Economic Geography

environment. Likewise,modern (post-1960) economic geography largely sub-disciplined itself around aninterest in employment (e.g. industrial geography) or in nature (e.g. environmentalgeography). Fortunately, the nature of the debate is changing rapidly andpolitical, business and environmental leaders have recognized that economicdevelopment and environmental sustainability, the two central challenges facingthe world in the twenty-first century, depend on each other as potentially mutuallycompatible imperatives. Recognition that economic evolution is driven byinnovations of all kinds that restructure relations between economy and environmentsupports this view. If these restructurings have been overwhelmingly negative forthe environment in the past, a re-calibration of institutional and technologicalinnovation towards a Green Paradigm that seeks to realize positive sum relationshipsbetween economy and environment is feasible. Moreover, a Green Paradigm needsto be both global in scope and sensitive to geographically uniqueness. Economy–environment relationships are distinctive in particular places and connected acrossspace; climate warming, for example, is a global phenomenon in which processesand outcomes are locally varied. The vital role for environmental economicgeography is to assess how place and space influence economy–environmentrelations that are site-specific, globally interdependent and multi-scalar, and toprescribe (local–global) relations that will realize economic and environmentalvalues. Normatively, with respect to the achievement of economic and environ-mental values: How should innovation systems be organized globally and locally?What is the proper distribution of economic activities? How should cities andresource peripheries be remapped? How should value chains that directly andindirectly link multi-faceted (resource, manufacturing and service activities)activities in the supply of goods and services for consumers best be organizedlocally and globally? These are some of the fascinating questions facing environmentaleconomic geography.

The role of neighbourhood density in transposed-letter priming

We investigated how transposed-letter (TL) priming effects are modulated by neighbourhood density in lexical decision task and cross-case same-different task. Robust identity priming and TL priming effects were observed in both tasks. Neighbourhood density facilitated ‘word’ decisions and reduced the size of identity priming effect in the lexical decision task. It had no effect on the same-different task, and did not modulate identity or TL priming. We take these results as indicating that neighbourhood density modulates priming during lexical access. In the lexical decision task, the difference between identity priming and TL priming was reduced for words from high-density neighbourhood. The last finding is at odds with the ‘lexical tuning’ hypothesis which has been used to explain modulatory effects of neighbourhood density on masked form priming effects. We also discuss implication of the results for various letter position coding schemes.

Effects of onset density in preschool children: Implications for development of phonological awareness and phonological representation

ABSTRACTNeighborhood density influences adult performance on several word processing tasks. Some studies show age-related effects of density on children's performance, reflecting a developmental restructuring of the mental lexicon from holistic into segmental representations that may play a role in phonological awareness. To further investigate density effects and their implications for development of phonological awareness, we compared performance on dense and sparse onset words. We adapted these materials to three phonological awareness tests that were pretested on adults then administered to preschool children who were expected to vary in phonological awareness skills. For both the adults and the children who passed a phonological awareness screening task, dense onset neighborhoods were associated with slower reaction times and increased errors. A separate comparison of word repetition by the children who passed and who did not pass the phoneme awareness screening failed to provide evidence that lexical restructuring was a sufficient condition for the attainment of phonological awareness. Both groups of children more accurately repeated words from high onset density neighborhoods, regardless of the level of their phonological awareness. Thus, we find no evidence of either age- or ability-driven effects in children's performance, contradictory to a view that the attainment of phoneme awareness relates to developmental changes in the segmental representation of words in dense neighborhoods.

Environmental impacts of natural gas distribution networks within urban neighborhoods

This study uses the life cycle assessment methodology to analyze the type and origin of environmental impacts related to natural gas distribution networks in high and low density neighborhoods, and compares the environmental performance of two infrastructures in low density neighborhoods: a standard natural gas grid and a discontinuous system based on propane tanks. The results show that the impact per dwelling in the environmental categories studied is between 1.9 and 4.8 times higher in a low density neighborhood, depending on the impact category. Besides, in high density areas the main impact originates from components and materials related to the buildings and dwellings, whereas in low density areas the main impact originates on the neighborhood network. Given this last result, the advisability of substituting the neighborhood network by a discontinuous system based on propane tanks has been evaluated, obtaining as a result that when a single neighborhood pipe, longer than 1 km, is required to reach one user, it is environmentally preferable for all the studied environmental categories to use the propane tank system.