North American Urban Areas Research Articles

Do stop-signs improve the safety for all road users? A before-after study of stop-controlled intersections using video-based trajectories and surrogate measures of safety

Converting minor-approach-only stop (MAS) intersections to all-way-stop (AWS) intersections is a prevailing safety countermeasure in North American urban areas. Although the general population positively perceives the installation of stop-signs in residential areas, little research has investigated the impact of AWS on road safety and road user behaviour. This paper investigated the safety effectiveness of converting MAS to AWS intersections using an observational before and after approach and surrogate measures of safety. More specifically, the safety impacts of AWS conversion were investigated using multiple indicators, including vehicle speed measures, vehicle–pedestrian, vehicle-cyclist, vehicles-vehicle interactions as well as yielding rates before and after the treatment implementation. A multi-level regression approach was adopted to determine the effect of stop signs controlling for built environments, traffic exposure, and intersection geometry factors as well as site-specific unobserved heterogeneity.A unique sample of 31 intersections were used in this before-after study. From this sample, video data were collected before and after implementing AWS. In total, 245 h of video were automatically processed and corrected using a specialized computer vision software. More than 68,000 (37,668 before and 31,305 after AWS treatment) road user trajectories were obtained from 104 approaches. The results show that the conversion of MAS to AWS intersections significantly decreased vehicle speed and increased post-encroachment time. This work also shows that implementing AWS significantly increased the yielding rates from 45.7% to 76.7% in MAS conditions and reduced the average speed of motor-vehicles. Using multi-level regression model, it is estimated that when the intersection was converted from MAS to AWS, the minimum speed in the major approaches was reduced by 60.0%.

Contemporary climatic analogs for 540 North American urban areas in the late 21st century

A major challenge in articulating human dimensions of climate change lies in translating global climate forecasts into impact assessments that are intuitive to the public. Climate-analog mapping involves matching the expected future climate at a location (e.g., a person’s city of residence) with current climate of another, potentially familiar, location - thereby providing a more relatable, place-based assessment of climate change. For 540 North American urban areas, we used climate-analog mapping to identify the location that has a contemporary climate most similar to each urban area’s expected 2080’s climate. We show that climate of most urban areas will shift considerably and become either more akin to contemporary climates hundreds of kilometers away and mainly to the south or will have no modern equivalent. Combined with an interactive web application, we provide an intuitive means of raising public awareness of the implications of climate change for 250 million urban residents.

Dominance of Pavement Ants (Hymenoptera: Formicidae) in Residential Areas of West Lafayette, IN, USA1

Abstract Ant abundance and diversity are affected by numerous factors, including competition. Pavement ants (Tetramorium immigrans Santschi) are by far the most dominant species in North American urban areas, and so likely engage in interspecific competition and thus affect the abundance and diversity of other ant species. Ant abundance and diversity were monitored at the level of genus at two field sites in West Lafayette, IN, taking into account temperature, humidity, and habitat as possible factors in ant distribution. Temperature was found to be a significant factor affecting the abundance of ants, while humidity was not. The different habitats at the two locations resulted in the presence of different genera. The number of pavement ants was positively correlated with the number of cornfield ants (Lasius neoniger Emery) in Copper Beech Apartments, but not at Purdue Village. There was also a slightly greater diversity of ants found at Copper Beech Apartments.

Permeable pavement in northern North American urban areas: research review and knowledge gaps

ABSTRACTA majority of existing permeable pavement installations are related to parking lots and commercial areas with low speeds and light traffic loads. During the past two decades, a tremendous amount of progress has been made with regard to the application of permeable pavements regarding mix design, hydrologic design, water quality assessment and maintenance requirements. Review of the literature revealed, however, that there are still many important questions that must be answered before permeable pavements can be fully integrated in urban roads, especially in highways with high speeds and loads. This paper summarises the major research progress in the above listed areas and identifies research needs. Research needs are summarised under four topics: (1) structural and materials property, (2) hydrologic performance, (3) water quality and (4) maintenance. Research needs are further organised based on their immediate, short-term and long-term impact.

Turning cities inside out: transportation and the resurgence of downtowns in North America

North American urban areas have changed dramatically over the last four dec- ades. While downtowns were thought to be in long-term decline 40 years ago, central business districts are today the most vibrant residential and commercial centers throughout a largely suburban continent. This paper examines the role of transportation technology and policy in the earlier decline and recent revival of American downtowns and examines challenges to the continuation of urban regeneration. Major recent investments in physical improvements in central cities have been complemented by a dramatic shift in the locus of logistical and goods processing activities from city centers to outlying areas. While many tout the energy efficiency and environmental benefits of walkable and denser inner cities, a more complete accounting of their impacts also requires analysis of increasing urban congestion and the steady rise in urban goods movement in support of the new development patterns.

A Comparison of Summertime Secondary Organic Aerosol Source Contributions at Contrasting Urban Locations

Primary and secondary sources contributing to atmospheric organic aerosol during the months of July and August were quantitatively assessed in three North American urban areas: Cleveland, Ohio, and Detroit, Michigan, in the Midwest region and Riverside, California, in the Los Angeles Air Basin. Organic molecular marker species unique to primary aerosol sources and secondarytracers derived from isoprene, alpha-pinene, beta-caryophyllene, and toluene were measured using gas chromatography-mass spectrometry. Source contributions from motor vehicles, biomass burning, vegetative detritus, and secondary organic aerosol (SOA) were estimated using chemical mass balance (CMB) modeling. In Cleveland, primary sources accounted for 37 +/- 2% of ambient organic carbon, measured biogenic and anthropogenic secondary sources contributed 46 +/- 6%, and other unknown sources contributed 17 +/- 4%. Similarly, Detroit aerosol was determined to be 44 +/- 5% primary and 37 +/- 3% secondary, while 19 +/- 7% was unaccounted for by measured sources. In Riverside, 21 +/- 3% of organic carbon came from primary sources, 26 +/- 5% was attributed to measured secondary sources, and 53 +/- 3% came from other sources that were expected to be secondary in nature. The comparison of samples across these two regions demonstrated that summertime SOA in the Midwestern United States was substantially different from the summertime SOA in the Los Angeles Air Basin and indicated the need to exert caution when generalizing about the sources and nature of SOA across different urban areas. Furthermore, the results of this study suggestthatthe contemporary understanding of SOA sources and formation mechanisms is satisfactory to explainthe majority of SOA in the Midwest Additional SOA sources and mechanisms of formation are needed to explain the majority of SOA in the Los Angeles Air Basin.

In search of a stable urban regime for Montreal: issues and challenges in metropolitan development

As with many major North American urban areas since the 1960s, Montreal has faced contextual changes that have brought to the fore the question of its development. However, because of its history and the uncertainties linked with Quebec's constitutional future, attempts to stimulate its development have required certain compromises, often with unexpected results. In order to evaluate the performance of coalitions formed with the objective of meeting the challenges associated with urban and metropolitan development, we have drawn upon the concept of urban regimes. Focusing specifically on Montreal, we ask whether it is possible to transpose urban regime analyses that consider both structural and cultural factors specific to local organized forces. Revealing though they might be, these analyses nevertheless possess certain limitations, notably the underestimation of the weight and increasing importance of players and forces occurring on a metropolitan scale. This is particularly true in the case of Montreal.

Sustainability and local economic development in Canada and the United States

This article provides a description, summary, and analysis of representative efforts to deal with the challenges to sustainability that result from the predominant patterns of land use in the metropolitan areas of North America. Two broad categories of public policies are considered: management and control of peripheral growth and revitalization efforts to improve the competitiveness of older urban areas. Metropolitan efforts to achieve more sustainable development through management of new development tend to rely more on voluntary agreements that preserve local government autonomy than on regional collaborations. The regional approaches that have been implemented to date have had only limited effectiveness. Efforts to make older communities more competitive with greenfield development have focused on downtown revitalization, industrial location incentives, business incubators, and neighborhood revitalization. While most of these efforts are carried out by state and local governments, faith-based organizations have come to play an increasingly important role. Downtown and industrial revitalization initiatives frequently provide only limited benefits despite their high public cost. Business incubators and neighborhood improvement efforts appear to be more cost effective strategies. On balance, the lack of political will and the preferences of households and businesses for new, low-density developments are likely to continue to foster unsustainable forms of urban development in most North American urban areas.

High-Sensitivity GPS Data Classification Based on Signal Degradation Conditions

High-sensitivity global positioning system (GPS) can significantly improve system availability in signal degradation environments but is limited by low reliability. This paper presents a fuzzy inference system to classify high-sensitivity GPS data based on two geo-signal degradation measures that incorporates GPS-signal quality and geometry information. Effective and proper data classification by applying the proposed method is demonstrated through several field tests in the typical North American urban areas

Funds of Knowledge: Theorizing Practices in Households, Communities and Classrooms (review)

Reviewed by: Funds of Knowledge: Theorizing Practices in Households, Communities and Classrooms Sandra R. Schecter González, Norma, Moll, Luis C., & Amanti, Cathy . (Eds.). (2005). Funds of Knowledge: Theorizing Practices in Households, Communities and Classrooms. Mahwah, NJ: Lawrence Erlbaum. Pp. 307, US$34.50. This edited volume brings together new and previously published articles and essays by university researchers and practitioners who have collaborated over an 18-year period on the Funds of Knowledge project, based at the University of Arizona. The book is divided into four parts. The first of these offers four essays on the theoretical underpinnings of the Funds of Knowledge project; a second part, containing six chapters, describes various teacher research initiatives in the greater Tucson area. The four chapters in Part Three discuss work within the same conceptual framework conducted in urban contexts in the eastern United States, while in Part Four a concluding commentary by Luis Moll links and summarizes the papers. The title of the volume (and the project) relates to the authors' central premise that linguistic and ethnic minority families possess valuable social and intellectual resources, particular to their trajectories and circumstances, upon which formal classroom instruction can effectively be built. The envisioned approach toward realizing these pedagogic goals is ethnographically grounded action research, wherein reflective practitioners seek to uncover the processes and practices within families and social networks that both give sense to and help people make sense of their daily lives. While this theoretical premise and this (teacher-as-learner) approach should by now be self-evident, sadly, in a majority of North American contexts, a deficit model of education is still prevalent, notwithstanding the impoverished academic results associated with its [End Page 298] legacy. This volume's contents, and its advocacy refrain, therefore remain timely: We could do with some reminding. Foremost among the volume's strengths is that it brings together an important body of work that has served as a reference point for researchers and educators with a commitment to principles and practices of community-based pedagogy. Papers published in the introductory sections by Moll and colleagues provide insights into the theoretical shaping of this seminal work and the theorizing practices that have produced a lexicon with far-ranging impact – funds of knowledge, reciprocal relations, networks of exchange, confianza. While the socio-political and economic contexts of the households described do not have direct analogues in Canada – we have not driven the middle classes out of our large cities, nor have we expelled minorities from rural areas into urban settings – the basic tenets of the Funds of Knowledge project are applicable to schooling contexts within a majority of North American urban areas, that is, schooling contexts defined by significant linguistic and cultural diversity. Moreover, the examples provided by practitioner authors on the ground constitute excellent points of departure for educators with the will and imagination to empower parents and other community members in the education of their children. A stunning essay by Tucson teacher Marla Hensley on her own efforts to tap into the resources of families – with respect, for example, to quilting, tortilla making, and weaving – concludes with a variety of heuristics, including involving parents in specific class projects that would benefit from their linguistic and cultural resources and integrating the work/occupations of parents into thematic planning of class curricula. Tucson teacher Cathy Amanti's contribution discusses a learning module centring on students' extensive knowledge of horses. The majority of the Mexicano/a students in the Tucson area have frequent contact with horses, usually on ranches owned by relatives; thus, the topic provides a strategic entry point into many school subjects. Amanti describes how students collect texts and other material and relate them to their experience, or schema. These same students compile rich Spanish and English vocabularies describing the upkeep and functions or activities of these valued domestic animals. The horses' bodies provide an entrance into the biological sciences, including anatomy, cell theory, gestation, and evolution. In another essay, Anne Browning-Aiken applies the students' and their families' extensive knowledge of copper mining, a major boom–bust industry in the Tucson area, to the formal study of history, language, mathematics, and science. For example, in...

Real-Time Human Perceptions: Toward a Bicycle Level of Service

The primary focus of this study by Sprinkle Consulting Engineers, Inc. is to develop a bicycle-quality, or level-of-service, model for applications in U.S. metropolitan areas. Although there are several model forms being used throughout the United States that attempt to quantify road suitability or the quality of service afforded bicyclists traveling the street and roadway networks of urbanized areas, to date there have been no statistically calibrated models published. The statistically calibrated level-of-service model described here is based on real-time perceptions from bicyclists traveling in actual urban traffic and roadway conditions. The study’s participants represented a cross section of age, gender, experience level, and geographic origin of the population of cyclists that use the metropolitan road networks in the United States. The test course is representative of the collector and arterial street systems of North American urban areas. Although further hypothesis testing is being conducted and additional studies are planned to test the need for disaggregate models for central business district streets with high turnover parking, truck routes, and two-lane high-speed rural highways, the general bicycle level-of-service model reported here is highly reliable, has a high correlation coefficient ( R2 = 0.73), and is transferable to the vast majority of United States metropolitan areas. The study reveals that pavement-surface conditions and striping of bicycle lanes are important factors in the quality of service.

Revision of 20 years of Dobson total ozone data at Uccle (Belgium): Fictitious Dobson total ozone trends induced by sulfur dioxide trends

Since July 1971, total ozone measurements have been performed at Uccle (50°48′N, 4°21′E) with the Dobson spectrophotometer 40. All the individual measurements were reevaluated after a careful homogenization, using the detailed calibration history of the instrument. Special care was taken to assure the consistency between direct Sun (DS) and zenith sky (ZS) measurements. The monthly mean values of percentage differences between the quasi‐simultaneous direct Sun and zenith sky measurements show a weak modulation, probably induced by long‐term changes in the mean vertical ozone distribution. The overall standard deviation of the percentage differences between the two types of observations amounts to 1.72%. From a detailed comparison of our revised data over the period 1971–1986 with the results of an approximate revision on a month‐by‐month basis (used in the Report of the International Ozone Trends Panel), it is concluded that the latter method of revision is not reliable. The trend of the reduced thickness of the SO2 amount in the lower troposphere, as measured with the Brewer instrument 16 located at the same site as the Dobson spectrophotometer, is in agreement with the trend of the SO2 density near the ground which has been measured in the urban area of Brussels since 1968. From these two SO2 data sets the variation of the reduced SO2 amount since 1968 and the corresponding correction of the Dobson instrument data of Uccle were calculated on a month‐by‐month basis. Without the SO2 correction the revised Dobson data for the period from August 1971 through July 1991 show a statistically significant downward trend (± standard deviation) that amounts to −1.38 ± 0.50% per decade, while after the SO2 correction a nonsignificant trend of 0.31 ± 0.51% per decade is found. This means that the decrease of SO2 over the last two decades at Uccle has induced a fictitious Dobson total ozone trend of −1.69% per decade. At the subperiod for which reprocessed total ozone mapping spectrometer (TOMS) data are available (November 1978 to May 1990) our corrected Dobson data show a statistically significant downward trend (± standard deviation) of −2.93 ± 1.17% per decade which is consistent with the results from TOMS; this proves that analysis of total ozone data over time periods as short as one solar cycle does not allow to make conclusive statements about long‐term trends. The spectacular decrease of SO2 densities is not a regional phenomenon but has been generally ascertained in European and North American urban areas; therefore it should not be neglected in any study about global ozone trends derived from Dobson data.

Crowding and Human Reproduction

Studies of crowding in lower animals repeatedly demonstrate that compressed living conditions depress the ability of the species to reproduce. In a sample of 470 urban Toronto women we examined the effect of neighborhood and household crowding on the probability of a pregnancy and on the probability that any given product of the pregnancy will not survive until one year of age. Crowding did not influence fertility nor fetal and infant survival within the range of crowding found in this sample. If crowding has any influence on reproduction it would more profitably be investigated beyond the range of living density and housing markets found in North American urban areas.

Use of Diazepam in Hallucinogenic Drug Crises

The increasing spread of hallucinogenic-drug compounds with atropine-like action presents problems for physicians in North American urban areas. Dangers of using phenothiazines in treatment programs are no longer restricted to 5-dimethoxy-4-methyl-amphetamine (STP), but also to more routinely used illegal compounds. The doctor must assume that such drugs may be combined with a chemical having atropine-like action. Diazepam was used in the treatment of hallucinogenic-drug crises in 69 patients; 67 responded well. Diazepam seems to be suitable in supportive chemotherapy of "illusinogenic" drug crises.