Intersection Density Research Articles

Potential drivers of urban green space availability in Latin American cities

AbstractUrban green spaces play a critical role in regulating air temperature, reducing air pollution and enhancing people’s well being. Yet, existing data and research on potential drivers of urban green space availability in Latin America are limited. Here, focusing on 371 large cities in 11 countries in Latin America, we described the total and per capita variability of urban green space, its spatial configuration and green urban parks across the categories of cities’ natural, built and socioeconomic environments. We tested the relative importance of geographic (climate) versus city-level built environment (population, population density, street intersection density) and socioeconomic (city gross domestic product per capita, unemployment, education) drivers in explaining urban green space availability. We found a high level of heterogeneity in green space quantity across cities and across categories of cities’ environments. Relative to other city factors, climate zone had the largest influence in explaining the quantity of green space, whereas education, street intersection density and population density were the most important drivers of urban park availability. The significance of climate for green space availability, combined with the inequitable quantity of green space, indicates that cities have differing capacities to implement nature-based solutions for heat mitigation and health promotion.

Assessing Non-linear Influences of Urban Layout on Driving Travel Distance: A Mumbai Case Study

Introduction This study investigates the impact of built environment factors on travel behavior in Mumbai, India, focusing on the non-linear effects on driving distances. The rapid urbanization and complex urban of Mumbai constitute present challenges for sustainable transportation, necessitating a deeper understanding of how urban planning influences travel behavior. While demographic factors have often been highlighted in travel studies, this research prioritizes the role of built environment factors. Materials and Methods The study utilized Gradient Boosting Decision Trees (GBDT) to analyze household travel survey data from Mumbai, capturing the non-linear relationships between built environment variables and driving distances. Partial dependence plots were used to visualize these effects, and the relative importance of each variable was assessed to identify key determinants of travel behavior. Results The analysis identified trip time as the most influential factor in determining driving distances, followed by built environment characteristics, such as proximity to commercial areas and intersection density. Socio-demographic factors were found to have a comparatively low impact. Non-linear relationships were observed, such as the stabilization of driving distances beyond certain thresholds of block density and proximity to bus stops. Discussion The findings challenge the traditional emphasis on demographic factors in explaining travel behavior, highlighting the significant role of urban form. The study reveals that specific built environment factors, such as accessibility and connectivity, play a crucial role in shaping driving behavior in a rapidly urbanizing city like Mumbai. These results suggest that urban planning strategies should prioritize these factors to reduce car dependency. Conclusion This study underscores the importance of the built environment in influencing travel behavior in Mumbai, particularly in reducing driving distances. The insights gained offer valuable guidance for urban planners and policymakers aiming to promote sustainable mobility in rapidly developing cities. Further research is recommended to validate and expand upon these findings in other urban contexts.

Defining neighborhood walkability for children in the ELFE cohort study

Abstract Background Although walkability is known to be associated with obesity in adults, there is a paucity of data evaluating the association of walkability and health outcomes in children. In particular, little is known regarding the possible association with children’s mental health. Methods We used data from the Etude Longitudinale Française depuis l’Enfance (ELFE) cohort study. Participating mothers gave birth in 2011 in a representative sample of 320 maternity hospitals in mainland France. This pilot study is limited to participants in Paris and children at 5.5 years old. Walkability is defined by three parameters: population density (defined by census data), street connectivity (defined by intersection density), and land-use mix (entropy index). To approximate walkable areas, 500-meter street-network buffer zones were created around each participants address using a geographic information system. Children’s mental health was assessed using parent-reported Strengths and Difficulties Questionnaire at age 5.5 years. Results There was a total of 280 children in this pilot study. On measures of land-use mix, we found a mean of 0.79 (SD: 0.12), representing high accessibility. Residential and intersection density were highly correlated (p < 0.01). The walkability index demonstrated high variability among participants (mean: 10.6; SD: 10.44; range: -1.67 - 30.59). Conclusions Developing a walkability index is a multifactorial measure to describe a children’s neighborhood environment. Future work includes determining the association with children’s mental health disorders, while accounting for individual and neighborhood variables. This ecological model can inform social epidemiology and contextual disparities in children’s health. Key messages • Little is known about neighborhood walkability and the association with children’s mental health. • Using objective measures to calculate neighborhood composition and help elucidate this relationship.

Unraveling hierarchically ordered melt electro-written tissue engineering scaffolds: Morphological and mechanical insights

Addressing critical tissue defects treatment remains a pressing challenge in medicine and bioengineering. Tissue engineering (TE) scaffolds, characterized by porous architectures suitable to cell growth, is a pivotal solution. Recent advances in additive techniques have revolutionized scaffold fabrication, enabling precise control over complex porous structures. This study conducts a comprehensive analysis of hierarchically ordered melt electrospun written (MEW) TE scaffolds, elucidating the relationships between fabrication parameters and their morphological and mechanical properties. Leveraging the phenomenon of melt jet deposit buckling, characteristic hierarchically ordered porous architectures were attained. The study explores the fabrication potential of hierarchically ordered porous MEW architectures across varied voltages, feed rates, and needle sizes. Morphometric parameters, including percent porosity, density of fiber intersections, and fiber diameter, were identified. It was revealed that for feed rates exceeding 20 mm/s, resultant fiber diameters were unaffected by voltage. However, increasing voltage leads to noticeable reduction of mesh stiffness due to the coiled fibers presence. Exceptions occur at the feed rate of 20 mm/s and for needle G24, where stiffness surpasses those of regular primary pattern, which could be attributed to increased number of fiber interconnections.

Impact of urban road characteristics on vehicle speed: Insights from Brescia, Italy

In managing road infrastructures, a key benchmark is the 85th percentile of vehicle speeds (V85). While V85 can be derived from spot speed samples, these are often lacking on each urban road. Thus, prediction models become valuable tools for examining the relationship between V85 and road characteristics. Although various models exist for rural roads, the impact of roadside characteristics and markings on V85 in urban road networks has been partially investigated, and the effect of traffic calming measures remains fragmented.This study aims to address these gaps by applying a methodology that sheds light on the effects of some variables that influence V85 on urban roads. Specifically, the methodology selects and segments roads along the urban road network of the municipality of Brescia (Italy) and collects data on both road characteristics and 48,000+ spot speed information. Following data cleansing, it processes these data according to three different multiple regression models to analyse the influence of various predictors on V85. Once the best model is estimated, its performance is evaluated, and the final list of significant predictors is obtained.The results revealed that V85 increases with longer homogeneous segments, greater distance to successive intersections, bituminous conglomerate roads with more lanes, and the presence of trees, visible road markings, and posted speed limits. Conversely, V85 decreases in the presence of on-street parking and other obstacles (e.g., walls and road posts), when the density of road intersections and pedestrian crossings increases, when the left crossbar width increases and when the land use crossed is commercial or office, residential or industrial. Nevertheless, no significant effect was found for several traffic calming measures included in the model.These findings can assist road authorities in verifying road operating conditions and planning infrastructure interventions to reduce speeds, thereby creating a safer urban environment for all users.

The Influence of Morphological Elements of Urban Gated Communities on Road Network Connectivity: A Study of 120 Samples of the Central Districts of Jinan, China

Currently, the dominant gated communities (GCs) in Chinese cities have fragmented the urban road network, causing traffic congestion, energy consumption, carbon emissions, and environmental pollution. The morphological elements of GCs are key factors affecting road network connectivity. This paper aimed to explore the influence of the morphological elements of GCs on road network connectivity, to provide a quantitative basis for the evaluation and renovation of the connectivity of GCs, and to provide insights for urban planning and policy. This paper quantitatively analyzed the connectivity of GCs using 120 samples from the central districts of Jinan, China. Morphological elements were the independent variables, while route directness (RD) and the network distance (D) to the nearest entrance were the dependent variables. RD measured the internal connectivity, and D measured the connectivity between the internal and external road networks of GCs. GIS was used to measure RD and D, and SPSS was used to conduct a correlation analysis to identify significant variables. Multiple linear regression and LASSO regression were used to test the influence of these factors on RD and D. LASSO regression was employed to construct prediction models for RD and D. We found that intersection density had the greatest impact on RD, while the number of entrances and exits, and the scale of GCs, had the greatest impact on D. Using thresholds of D = 250 and RD = 1.3, the four types of GCs were classified and corresponding renovation measures were proposed.

Association between Built Environment and Bus Usage among Older Adults: Urban–Rural Differences in the Nonlinearities

Public transport improves mobility and well-being for the rapidly aging population. However, few planning interventions have addressed the urban–rural disparity in bus usage among older adults. Using data from Zhongshan, China, this study adopts the eXtreme Gradient Boosting (XGBoost) model to examine urban–rural differences in the nonlinear relationship between built environment and daily bus usage among elderly adults. The results indicate nonlinearities across all built environment variables and stronger effects of the built environment in rural areas. Distance to transit contributes the most in urban neighborhoods but least in rural ones. Furthermore, dwelling unit density and green space accessibility play the biggest roles in the rural context. Additionally, the most effective ranges of intersection density, land use mixture, and CBD accessibility are greater in rural areas. The findings facilitate fine-grained and diversified planning interventions to facilitate bus usage among older adults in both urban and rural areas.

Neighbourhood environments and cognitive health in the longitudinal Personality and Total Health (PATH) through life study: A 12-year follow-up of older Australians

BackgroundUrban neighbourhood environments may impact older adults’ cognitive health. However, longitudinal studies examining key environmental correlates of cognitive health are lacking. We estimated cross-sectional and longitudinal associations of neighbourhood built and natural environments and ambient air pollution with multiple cognitive health outcomes in Australian urban dwellers aged 60+ years. MethodsThe study included 1160 participants of the PATH Through Life study (60+ cohort) who were followed up for 12 years (four assessments; 2001/02 to 2013/15) and with data on socio-demographics, health, cognitive functions and diagnoses, and full residential address. Neighbourhood environmental features encompassed population and street-intersection densities, non-commercial land use mix, transit points, presence of blue space, percentages of commercial land, parkland and tree cover, and annual average PM2.5 and NO2 concentrations. All exposures except for tree cover were assessed at two time points. Generalised additive mixed models estimated associations of person-level average, and within-person changes in, exposures with cognitive functions. Multi-state hidden Markov models estimated the associations of neighbourhood attributes with transitions to/from mild cognitive impairment (MCI). ResultsDense, destination-rich neighbourhoods were associated with a lower likelihood of transition to MCI and reversal to no MCI. Positive cross-sectional and longitudinal associations of non-commercial land use mix, street intersection density and percentage of commercial land were observed especially with global cognition and processing speed. While access to parkland and blue spaces were associated with a lower risk of transition to MCI, the findings related to cognitive functions were mixed and supportive of an effect of parkland on verbal memory only. Higher levels of PM2.5 and NO2 were consistently associated with steeper declines and/or decreases in cognitive functions and worse cognitive states across time. ConclusionTo support cognitive health in ageing populations, neighbourhoods need to provide an optimal mix of environmental complexity, destinations and access to the natural environment and, at the same time, minimise ambient air pollution.

Scanning electron microscopy-based quantification of keratin and hyaluronic acid microstructure in electrospun scaffolds

BackgroundThe extracellular matrix (ECM) structural deficiencies in chronic wounds prevent the wounds from healing through natural physiological processes. Electrospun biocompatible polymers offer a platform to produce microstructure wound dressing materials that mimic the ECM containing various bioactives to address the deficiencies in the chronic wound healing process. Quantitative characterization of the electrospun fiber microstructure could provide valuable information on using fiber constructs to facilitate wound healing. This work employed a validated image analysis tool to quantitatively explain various parameters for the microstructure of six electrospun fiber constructs, D1{Polycaprolactone (PCL), Polyvinyl alcohol (PVA), Keratin}, D2{PCL, PVA, keratin, Co-enzyme Q10 (CoQ10)}, D3 (PCL, PVA, keratin, mupirocin), D4 (PCL, PVA, keratin, CoQ10, mupirocin, valsartan), D5 {PVA, Hyaluronic acid (HA)}, and D6 (PVA), using scanning electron microscopy imaging modality.ResultsThe fiber intersection density (FID) parameter was quantified in the formulations, e.g., 0.272% for D5 and 0.416% for D4. Orientation histograms for D1 and D6 are characteristic of isotropic materials, while orientations for D2 and D3 indicate anisotropy with 2 preferred orientations in each formulation. D4 and D5 present orientations characteristic of transversely isotropic materials. The tortuosity for D2 and D4 indicates almost straight fiber segments, in contrast with undulated fiber segments in all other formulations. Furthermore, the mean fiber diameter was quantified, e.g., 1.414 and 1.630 mm for D3 and D4, respectively.ConclusionCo-electrospun PVA/PCL microfibers offer great potential for controlled delivery of bioactives needed to accelerate the healing of chronic wounds. This image-based analysis technology quantitatively characterized different formulations of electrospun fiber scaffolds. This analysis sets the stage for future study that utilizes microstructural information in finite element biomechanical modeling, to investigate possible influence of structure-based mechanical factors on the ECM restorative potential of wound dressings. Adjustment of electrospinning conditions could produce fabricated constructs like the native ECM structural components with a functional role in wound healing.

Examining social-demographic determinants of bike-sharing station capacity

This study applied Negative Binomial models to examine the social-demographic determinants of bike-sharing station capacity. It used social-demographic data from Smart Location Database and over 7,000 bike-sharing stations located in the United States. Results revealed that the station's city, households with no cars, the percentage of workers aged 18–64, gas prices, the Caucasian population, gross residential density on unprotected land, intersection density, and low to medium-earning workers are associated with the increase in station capacity. Contrarily, station capacity decreased with vehicle miles traveled and the number of high-earning workers. Findings are crucial to planners and operators in improving bike-sharing operations.

Investigation of the road network structure around rail transit stations

This study examined the connectivity of road networks around rail transit stations in İzmir, Türkiye, using intersection density and connected node ratio metrics. The analysis was conducted within 800 m, 600 m, and 400 m catchment areas around these stations, which were considered reasonable walking distances. Rail transit stations and road networks were digitized using ArcGIS Pro software. The research identified variations in connectivity scores among different stations and buffer zones. Stations in high-density areas like Konak and those near the ferry port showed higher connectivity scores, indicating well-integrated street networks that support multimodal transportation. In contrast, stations such as Ataşehir and Mavişehir, where intersection densities were lower, demonstrated significant connectivity challenges, underscoring the necessity for targeted urban planning interventions.

Spatial Characteristics of Multidimensional Urban Vitality and Its Impact Mechanisms by the Built Environment

Urban vitality, intricately connected to urban morphology, has long been a cornerstone of urban planning and design. The accelerated pace of urbanization has created abundant living and working spaces, but it has also brought about a series of issues such as traffic congestion, environmental pollution, insufficient public spaces, and uneven urban development, leading to a decline in urban vitality. The spatial distribution patterns of urban vitality and their influencing factors are diverse and vary across different cities, necessitating a multidimensional exploration of the relationship between urban vitality and the built environment. Utilizing the central urban area of Beijing as a case study, this research leverages multi-source urban spatial data to delineate the spatial characteristics of social, economic, cultural, and comprehensive vitality. Furthermore, a comprehensive set of built-environment indicators is developed across five dimensions to analyze their correlation with urban vitality. The results indicate: (1) There is a significant spatial clustering of various vitality types in Beijing, with a pronounced correlation between high-density population aggregation and vigorous economic activities. (2) Subdistricts exhibiting high social vitality display an “n”-shaped distribution around the Second Ring Road. In contrast, those with high economic vitality are concentrated along Chang’an Street and various district commercial centers. High cultural vitality subdistricts are distributed in a northwest–southeast trajectory from the Fourth Ring Road to the Second Ring Road, and subdistricts with high comprehensive vitality exhibit a concentric distribution radiating outwards from the center. (3) Social vitality is most closely related to comprehensive vitality, and the various vitality types in Beijing’s central urban area develop relatively evenly. (4) The built environment significantly affects all types of urban vitality. Factors such as floor area ratio, POI density, POI mixing degree, and intersection density are fundamental to enhancing urban vitality, whereas the greening rate somewhat inhibits it. (5) Future spatial planning should utilize the radiating effect of high-vitality subdistricts to optimize population distribution, enhance POI mixing, increase metro station density, and strengthen critical urban structures for synergistic economic and cultural development. This study provides a foundation and promotion strategies for optimizing the layout and enhancing vitality at the subdistrict scale within Beijing’s central urban area.

Moderation Effects of Streetscape Perceptions on the Associations Between Accessibility, Land Use Mix, and Bike-Sharing Use: Cross-Sectional Study.

Cycling is known to be beneficial for human health. Studies have suggested significant associations of physical activity with macroscale built environments and streetscapes. However, whether good streetscapes can amplify the benefits of a favorable built environment on physical activity remains unknown. This study examines whether streetscape perceptions can modify the associations between accessibility, land use mix, and bike-sharing use. This cross-sectional study used data from 18,019,266 bike-sharing orders during weekends in Shanghai, China. A 500 × 500 m grid was selected as the analysis unit to allocate data. Bike-sharing use was defined as the number of bike-sharing origins. Street view images and a human-machine adversarial scoring framework were combined to evaluate lively, safety, and wealthy perceptions. Negative binomial regression was developed to examine the independent effects of the three perceptual factors in both the univariate model and fully adjusted model, controlling for population density, average building height, distance to nearest transit, number of bus stations, number of points of interest, distance to the nearest park, and distance to the central business district. The moderation effect was then investigated through the interaction term between streetscape perception and accessibility and land use mix, based on the fully adjusted model. We also tested whether the findings of streetscape moderation effects are robust when examinations are performed at different geographic scales, using a small-sample statistics approach and different operationalizations of land use mix and accessibility. High levels of lively, safety, and wealthy perceptions were correlated with more bike-sharing activities. There were negative effects for the interactions between the land use Herfindahl-Hirschman index with the lively perception (β=-0.63; P=.01) and safety perception (β=-0.52; P=.001). The interaction between the lively perception and road intersection density was positively associated with the number of bike-sharing uses (β=0.43; P=.08). Among these, the lively perception showed the greatest independent effect (β=1.29; P<.001), followed by the safety perception (β=1.22; P=.001) and wealthy perception (β=0.72; P=.001). The findings were robust in the three sensitivity analyses. A safer and livelier streetscape can enhance the benefits of land use mix in promoting bike-sharing use, with a safer streetscape also intensifying the effect of accessibility. Interventions focused on streetscape perceptions can encourage cycling behavior and enhance the benefits of accessibility and land use mix. This study also contributes to the literature on potential moderators of built environment healthy behavior associations from the perspective of microscale environmental perceptions.

Impact of Neighborhood Urban Morphologies on Walkability Using Spatial Multi-Criteria Analysis

With the increase in car domination, air pollution, traffic congestion, and urban sprawl, sustainable, livable, creative, and walkable cities are critical, now more than ever, for improving quality of life. The effect of neighborhood urban morphologies on walkability has received much attention in recent years. In this vein, the main research question is: how do different neighborhood urban morphologies impact the level of walkability in urban environments, and what are the essential elements impacting the walkability index? Thus, this research aims to determine the impact of urban morphology on walkability in the city of Alexandria, Egypt, as a case study by utilizing multi-spatial analysis. In particular, the study focused on assessing the walkability of four different study areas that vary according to their urban morphology: Kafr–Abdo, Smouha, Latin Quarter, and Roushdy areas. The analysis utilized GIS to calculate a number of indicators to reach the final walkability index for each study area. Results helped to identify the neighborhoods characterized by the lowest level of pedestrian walkability in relation to the area’s urban morphology in an attempt to help decision-makers suggest the appropriate interventions for those areas. The aggregated index results showed that the highest walkability index was that of the gridiron morphology, followed by the linear morphology, with the radial and organic morphologies coming in behind them, respectively. The composite walkability index values were 0.364, 0.247, 0.232 and 0.225, respectively. The reason for this is mainly the presence of the commercial density, intersection density, street density, services density, BCR, and residential density.

The relationship between neighbourhood built characteristics, physical activity, and health-related fitness in urban dwelling Canadian adults: A mediation analysis.

ObjectivePhysical activity supportive environments have the potential to promote health-related fitness in adults. However, the extent to which neighbourhood built characteristics promote health-related fitness via physical activity has received little research attention. Therefore, our objective was to estimate the indirect and direct effects between neighbourhood built characteristics and health-related fitness mediated by physical activity. MethodsUsing cross-sectional data collected between 2014 and 2019, we merged neighbourhood built characteristics, physical activity, and health-related fitness variables, derived from two Canadian national databases. Using these data, we estimated sex-stratified covariate-adjusted path models (males: n = 983 to 2796 and females: n = 962 to 2835) to assess if accelerometer-measured light, moderate, and vigorous intensity physical activity mediated associations between objectively measured neighbourhood built characteristics (intersection density, dwelling density, points of interest, and transit density) and health-related fitness (grip strength, jump height, V̇O2max, and flexibility). Across 16 sex-specific models, we estimated 48 indirect and 16 direct effects. ResultsConcerning significant associations, for males we found that 16.6% of indirect and 18.8% of direct were negative and 4.2% of indirect and 0% of direct were positive. For females, we found that 12.5% of indirect and 0% of direct were negative and 0% of indirect and 25% of direct effects were positive. ConclusionsIndividual Canadian Active Living Environment built characteristics are positively associated with moderate-intensity physical activity and negatively associated with light-intensity physical activity. Further, associations between activity friendly neighbourhood characteristics and health related-fitness may be distinct from physical activity.

Associations of neighbourhood attributes with depression in mid-age and older adults: the moderating role of traffic-related air pollution and neighbourhood socioeconomic status

ABSTRACT We aimed to examine whether features of the natural, built and socioeconomic neighbourhood environments were related to depressive symptoms in Australian mid-age and older adults; and whether traffic-related air pollution (TRAP) (NO2) and area-level SES moderated the associations. A total of 4141 of participants (M age = 61 years) were included in this cross-sectional study. Neighbourhood environmental characteristics included percentages of parkland, blue space and commercial land use, population density (persons/hectare), street intersection density (intersections/km2) within 1 km residential buffers. Annual mean concentrations of nitrogen dioxide (NO2) were included. In total-effect models, greater street intersection connectivity was associated with fewer depressive symptoms. Population density was positively associated with depressive symptoms in direct-effect models. Residents from disadvantaged areas with low levels of NO2 and with greater commercial land use coverage reported fewer depressive symptoms. In contrast, residents were more likely to report depressive symptoms with greater coverage of commercial land use in high SES neighbourhoods with low levels of NO2. Street connectivity and population density play a role in the maintenance of mental health in older adults. NO2 and area-level SES are moderators of commercial land use-depression associations, and this knowledge can better inform planning of commercial destinations and facilities in urban environments.

Study on the Morphological Analysis and Evolution of the Street Network in the Historic Urban Area of Changsha City from 1872–2023

This study focuses on the streets and spatial networks of the historic urban area in Changsha, the capital of Hunan Province, China, by mainly investigating the evolution of their geometric and topological characteristics. It draws on the theories and methods of urban morphology and space syntax, combines the digital historical maps at different times, and uses methods such as historical map spatial interpretation, geographic information system (GIS), sDNA tools, and urban morphological parameter analysis to explore and sort out the evolutionary process of the street and alley network in Changsha from the early modern period to the present. The paper constructs a parameter system for analyzing the street and alley network of historic urban areas from a geometric and topological perspective. It introduces the indicators of road density, road orientation, intersection density, and approaches such as closeness, betweenness, and intelligibility in space syntax into the parameter analysis framework of street and alley network morphology and spatial characteristics evolution. By comparing the changes in various parameters at different spatial scales, the process of the spatial order evolution of the street and alley network in the historic urban area is analyzed, and the evolutionary rules of the various periods’ morphological characteristics are extracted.

Spatiotemporal impacts of metro network structure on land use change

Numerous studies have presented compelling findings regarding the favorable influence exerted by the construction of metro systems on the development of land use along the routes. However, the effects of metro network structure on land use change, especially the long-term dynamic effects, remain uncertain. To address this gap, this research utilizes land use coverage data and metro network data from Wuhan, China, spanning the period from 2014 to 2019. A complex network model is employed to analyze changes in the metro network structure, and the GTWR model is employed to investigate the impact of the of metro network structure on land use change. The results indicate that metro construction effectively stimulates land use change along the routes, predominantly leading to the conversion of non-construction land into construction land. Global accessibility, degree centrality, betweenness centrality, and eigenvector centrality, within the metro network structure attributes demonstrate significant positive effects on land use change, and these effects exhibit considerable spatiotemporal non-stationarity. Additionally, built environment factors surrounding metro stations, such as population density, plot ratio, street intersection density, and the quantity of bus stops, also exhibit notably spatiotemporal effects on land use change. These findings indicate that government agencies and urban planners should concentrate on optimizing the distribution of the urban metro network to improve its overall structural efficiency. When planning the construction of the metro network, careful attention should be paid to the built environment near the stations to effectively facilitate land use development in the vicinity.

Safety performance of dedicated and preferential bus lanes using multivariate negative binomial models for Bogotá, Colombia

Public transport priority systems such as Bus Rapid Transit (BRT) and Buses with High Level of Service (BHLS) are top-rated solutions to mobility in low-income and middle-income cities. There is scientific agreement that the safety performance level of these systems depends on their functional, operational, and infrastructure characteristics. However, there needs to be more evidence on how the different characteristics of bus corridors might influence safety. This paper aims to shed some light on this area by structuring a multivariate negative binomial model comparing crash risk on arterial roads, BRT, and BHLS corridors in Bogotá, Colombia. The analyzed infrastructure includes 712.1 km of arterial roads with standard bus service, 194.1 km of BRT network, and 135.6 km of BHLS network. The study considered crashes from 2015 to 2018 –fatalities, injuries, and property damage only– and 30 operational and infrastructure variables grouped into six classes –exposure, road design, infrastructure, public means of transport, and land use. A multicriteria process was applied for model selection, including the structure and predictive power based on [i] Akaike information criteria, [ii] K-fold cross-validation, and [iii] model parsimony. Relevant findings suggest that in terms of observed and expected accident rates and their relationship with the magnitude of exposure –logarithm of average annual traffic volumes at the peak hour (LOG_AAPHT) and the percentage of motorcycles, cars, buses, and trucks– the greatest risk of fatalities, injuries, and property damage occurs in the BHLS network. BRT network provides lower crash rates in less severe collisions while increasing injuries and fatalities. When comparing the BHLS network and the standard design of arterial roads, BHLS infrastructure, despite increasing mobility benefits, provides the lowest safety performance among the three analyzed networks. Individual factors of the study could also contribute to designing safer roads related to signalized intersection density and curvature. These findings support the unique characteristics and traffic dynamics present in the context of Bogotá that could inform and guide decisions of corresponding authorities in other highly dense urban areas from developing countries.

Evolving suburbs: measuring US subdivision street patterns over time

Street patterns in the United States have changed through time, evolving from a gridiron pattern to one dominated by culs- de- sac and loops by the 1950s. This change has made cities less convenient for pedestrians and cyclists to traverse. This research uses computational GIS techniques to analyze street pattern characteristics at the subdivision level to determine whether this trend toward disconnected street networks has continued over the past 70 years. Results show that the densities of three- and four- way intersections have increased in recent decades, though connectivity between subdivisions has not. Active transportation users may find their immediate neighbourhood more walkable, but remain unable to commute comfortably using those modes. This research also identifies representative subdivisions from Wake County, North Carolina that best reflect this change toward increased intersection density and smaller blocks. The small numbers of entrances to subdivisions have remained largely unchanged for decades. This is identified as a crucial challenge facing suburban street network design for pedestrians and cyclists. Overall, the differences between subdivision street network design in the 1950s and the 2010s is noticeable.