Longitudinal association of built environment pattern with DXA-derived body fat in elderly Hong Kong Chinese: a latent profile analysis.

BACKGROUND: One major limitation of prior studies regarding the associations between built environment (BE) and obesity has been the use of anthropometric indices (e.g., body mass index [BMI]) for assessing obesity status, and there has been limited evidence of associations between BE and body fat. This study aimed to explore the longitudinal association between BE and body fat in a cohort of elderly Hong Kong Chinese and examine whether the BE-body fat associations differed by BMI categories. METHODS: Between 2001 and 2003, 3944 participants aged 65-98 years were recruited and followed for a mean of 6.4 years. BE characteristics were assessed via Geographic Information System. Body fat (%) at whole body and regional areas (trunk, limbs, android, and gynoid) were assessed by dual energy X-ray absorptiometry at baseline and three follow-ups. Latent profile analysis was used to derive BE class, and linear mixed-effects models were used to investigate the associations of BE class with changes in body fat. Stratified analyses by BMI categories were also conducted. RESULTS: Three BE classes were identified. Participants in Class 2 (characterized by greater open space and proportion of residential land use) had a slower increase in whole body fat (B = -0.403, 95% confidence interval [CI]: -0.780, -0.014) and limbs fat (-0.471, 95% CI: -0.870, -0.071) compared with participants in Class 1 (characterized by high proportion of commercial land use). There were significant interactions of BE class with BMI, and participants in Class 2 had a slower increase in whole body fat and regional fat compared with participants in Class 1 (B ranging from -0.987 [limbs] to -0.523 [gynoid]) among overweight and obese participants only. CONCLUSIONS: We found that those who resided in the areas characterized by greater open space and proportion of residential land use had a slower body fat increase.

Differential associations of the built environment on weight gain by sex and race/ethnicity but not age.

OBJECTIVE: To explore the built environment (BE) and weight change relationship by age, sex, and racial/ethnic subgroups in adults. METHODS: Weight trajectories were estimated using electronic health records for 115,260 insured Kaiser Permanente Washington members age 18-64 years. Member home addresses were geocoded using ArcGIS. Population, residential, and road intersection densities and counts of area supermarkets and fast food restaurants were measured with SmartMaps (800 and 5000-meter buffers) and categorized into tertiles. Linear mixed-effect models tested whether associations between BE features and weight gain at 1, 3, and 5 years differed by age, sex, and race/ethnicity, adjusting for demographics, baseline weight, and residential property values. RESULTS: Denser urban form and greater availability of supermarkets and fast food restaurants were associated with differential weight change across sex and race/ethnicity. At 5 years, the mean difference in weight change comparing the 3rd versus 1st tertile of residential density was significantly different between males (-0.49 kg, 95% CI: -0.68, -0.30) and females (-0.17 kg, 95% CI: -0.33, -0.01) (P-value for interaction = 0.011). Across race/ethnicity, the mean difference in weight change at 5 years for residential density was significantly different among non-Hispanic (NH) Whites (-0.47 kg, 95% CI: -0.61, -0.32), NH Blacks (-0.86 kg, 95% CI: -1.37, -0.36), Hispanics (0.10 kg, 95% CI: -0.46, 0.65), and NH Asians (0.44 kg, 95% CI: 0.10, 0.78) (P-value for interaction <0.001). These findings were consistent for other BE measures. CONCLUSION: The relationship between the built environment and weight change differs across demographic groups. Careful consideration of demographic differences in associations of BE and weight trajectories is warranted for investigating etiological mechanisms and guiding intervention development.

Reimagining spaces where children play: developing guidance for thermally comfortable playgrounds in Canada.

SETTING: Planning and designing thermally comfortable outdoor spaces is increasingly important in the context of climate change, particularly as children are more vulnerable than adults to environmental extremes. However, existing playground standards focus on equipment and surfacing to reduce acute injuries, with no mention of potential negative health consequences related to heat illness, sun exposure, and other thermal extremes. The goal of this project was to develop proposed guidelines for designing thermally comfortable playgrounds in Canada for inclusion within the CAN/CSA-Z614 Children's playground equipment and surfacing standard. INTERVENTION: The project to develop guidance for thermally comfortable playgrounds was initiated with a municipal project in Windsor, Ontario, to increase shade, vegetation, and water features at parks and playgrounds to provide more comfortable experiences amid the increased frequency of hot days (≥30°C). The lack of available information to best manage environmental conditions led to a collaborative effort to build resources and raise awareness of best practices in the design of thermally comfortable playgrounds. OUTCOMES: A group of multidisciplinary experts developed technical guidance for improving thermal comfort at playgrounds, including a six-page thermal comfort annex adopted within a national playground and equipment standard. The annex has been used by Canadian schools in a competition to design and implement green playgrounds. IMPLICATIONS: Both the technical report and the thermal comfort annex provide increased awareness and needed guidance for managing environmental conditions at playgrounds. Thermally safe and comfortable play spaces will help ensure that Canada's playgrounds are designed to minimize environmental health risks for children.

RéSUMé: CONTEXTE: À l'ère des changements climatiques, le confort thermique n'a jamais été si important pour la planification et l'aménagement d'espaces extérieurs, surtout car les enfants sont plus sensibles que les adultes aux chaleurs brûlantes. Cependant, les normes qui encadrent actuellement les aires de jeu s'articulent autour d'une logique de prévention de traumatismes. Elles portent donc principalement sur les équipements et leurs revêtements plutôt que sur les conséquences des canicules, des malaises liés à la chaleur et des insolations. L'objectif du présent projet est de rédiger un projet de directives pour favoriser le confort thermique des aires de jeu au Canada et d'intégrer ces directives à la norme CAN/CSA-Z614 Aires et équipements de jeu. INTERVENTION: Les origines du projet remontent à une action municipale à Windsor, en Ontario. Celle-ci avait pour but d'augmenter la quantité de zones d'ombres, de végétation et de jeux d'eau dans les parcs et les aires de jeu en vue de favoriser le confort thermique vu la fréquence croissante des canicules (≥30°C). Le constat de lacunes d'informations autour de la gestion des conditions écologiques a suscité une concertation pour créer des ressources et faire rayonner des pratiques d'aménagement optimales pour l'amélioration du confort thermique des aires de jeu. RéSULTATS: Une équipe transversale d'experts a rédigé des directives techniques pour améliorer le confort thermique des aires de jeu, ainsi qu'une annexe de six pages sur la question qui a été intégrée à une norme nationale. Dans le cadre d'un concours, des écoles canadiennes se sont servies de l'annexe comme référentiel pour penser et aménager des aires de jeu vertes. IMPLICATIONS: Le rapport technique et l'annexe mettent en valeur le besoin d'encadrer la gestion des facteurs environnementaux des aires de jeu. L'amélioration du confort thermique de ces espaces et la réduction des risques environnementaux permettent de protéger la santé des enfants au Canada.

Does the built environment have independent obesogenic power? Urban form and trajectories of weight gain.

OBJECTIVE: To determine whether selected features of the built environment can predict weight gain in a large longitudinal cohort of adults. METHODS: Weight trajectories over a 5-year period were obtained from electronic health records for 115,260 insured patients aged 18-64 years in the Kaiser Permanente Washington health care system. Home addresses were geocoded using ArcGIS. Built environment variables were population, residential unit, and road intersection densities captured using Euclidean-based SmartMaps at 800-m buffers. Counts of area supermarkets and fast food restaurants were obtained using network-based SmartMaps at 1600, and 5000-m buffers. Property values were a measure of socioeconomic status. Linear mixed effects models tested whether built environment variables at baseline were associated with long-term weight gain, adjusting for sex, age, race/ethnicity, Medicaid insurance, body weight, and residential property values. RESULTS: Built environment variables at baseline were associated with differences in baseline obesity prevalence and body mass index but had limited impact on weight trajectories. Mean weight gain for the full cohort was 0.06 kg at 1 year (95% CI: 0.03, 0.10); 0.64 kg at 3 years (95% CI: 0.59, 0.68), and 0.95 kg at 5 years (95% CI: 0.90, 1.00). In adjusted regression models, the top tertile of density metrics and frequency counts were associated with lower weight gain at 5-years follow-up compared to the bottom tertiles, though the mean differences in weight change for each follow-up year (1, 3, and 5) did not exceed 0.5 kg. CONCLUSIONS: Built environment variables that were associated with higher obesity prevalence at baseline had limited independent obesogenic power with respect to weight gain over time. Residential unit density had the strongest negative association with weight gain. Future work on the influence of built environment variables on health should also examine social context, including residential segregation and residential mobility.

Neighborhood Built Environment and Late-Life Depression: A Multilevel Path Analysis in a Chinese Society.

OBJECTIVES: Neighborhood built environments (BEs) are increasingly recognized as being associated with late-life depression. However, their pathways are still understudied. This study investigates the mediating effects of physical and social activities (PA and SA) and functional ability (FA) in the relationships between BEs and late-life depression. METHODS: We conducted a cross-sectional analysis with data from 2,081 community-dwellers aged 65 years and older in Hong Kong in 2014. Two road-network-based service area buffers (200- and 500-m buffers) adjusted by terrain and slope from participants' residences were created to define the scope of neighborhoods. BEs comprised population density in District Council Constituency Areas, urban greenness, land-use diversity, and neighborhood facilities within 200- and 500-m buffers. Multilevel path analysis models were used. RESULTS: More urban greenness within both buffers and more commercial facilities within a 500-m buffer were directly associated with fewer depressive symptoms. SA mediated the relationship between the number of community facilities and depressive symptoms within a 200-m buffer. Neighborhood urban greenness and the number of commercial facilities had indirect associations on depressive symptoms within a 500-m buffer, which were mediated by FA. DISCUSSION: Our findings have implications for the ecological model of aging. The mediating effects of SA and FA underscore the importance of promoting active social lifestyles and maintaining FA for older adults' mental health in high-density cities. Policy implications on how to build age-friendly communities are discussed.

Built Environment Airborne Infection Control Strategies in Pandemic Alternative Care Sites.

OBJECTIVES, PURPOSES, OR AIM: To identify design strategies utilized in airborne infection isolation and biocontainment patient rooms that improve infection control potential in an alternative care environment. BACKGROUND: As SARS-CoV-2 spreads and health care facilities near or exceed capacity, facilities may implement alternative care sites (ACSs). With COVID-19 surges predicted, developing additional capacity in alternative facilities, including hotels and convention centers, into patient care environments requires early careful consideration of the existing space constraints, infrastructure, and modifications needed for patient care and infection control. Design-based strategies utilizing engineering solutions have the greatest impact, followed by medical and operational strategies. METHODS: This article evaluates infection control and environmental strategies in inpatient units and proposes system modifications to ACS surge facilities to reduce infection risk and improve care environments. RESULTS: Although adequate for an acute infectious disease outbreak, existing capacity in U.S. biocontainment units and airborne infection isolation rooms is not sufficient for widespread infection control and isolation during a pandemic. To improve patients' outcomes and decrease infection transmission risk in the alternative care facility, hospital planners, administrators, and clinicians can take cues from evidence-based strategies implemented in biocontainment units and standard inpatient rooms. CONCLUSIONS: Innovative technologies, including optimized air-handling systems with ultraviolet and particle filters, can be an essential part of an infection control strategy. For flexible surge capacity in future ACS and hospital projects, interdisciplinary design and management teams should apply strategies optimizing the treatment of both infectious patients and minimizing the risk to health care workers.

Health equity considerations in COVID-19: geospatial network analysis of the COVID-19 outbreak in the migrant population in Singapore.

BACKGROUND: Low-wage dormitory-dwelling migrant workers in Singapore were disproportionately affected by coronavirus disease 2019 (COVID-19) infection. This was attributed to communal living in high-density and unhygienic dormitory settings and a lack of inclusive protection systems. However, little is known about the roles of social and geospatial networks in COVID-19 transmission. The study examined the networks of non-work-related activities among migrant workers to inform the development of lockdown exit strategies and future pandemic preparedness. METHODS: A population-based survey was conducted with 509 migrant workers across the nation, and it assessed dormitory attributes, social ties, physical and mental health status, COVID-19-related variables and mobility patterns using a grid-based network questionnaire. Mobility paths from dormitories were presented based on purposes of visit. Two-mode social networks examined the structures and positions of networks between workers and visit areas with individual attributes. RESULTS: COVID-19 risk exposure was associated with the density of dormitory, social ties and visit areas. The migrant worker hub in the city centre was the most frequently visited for essential services of grocery shopping and remittance, followed by south central areas mainly for social gathering. The hub was positioned as the core with the highest degree of centrality with a cluster of workers exposed to COVID-19. CONCLUSIONS: Social and geospatial networks of migrant workers should be considered in the implementation of lockdown exit strategies while addressing the improvement of living conditions and monitoring systems. Essential services, like remittance and grocery shopping at affordable prices, need to be provided near to dormitories to minimize excess gatherings.

Satellite Imaging-Based Residential Greenness and Accelerometry Measured Physical Activity at Midlife-Population-Based Northern Finland Birth Cohort 1966 Study.

BACKGROUND: Recently, the importance of light physical activity (LPA) for health has been emphasized, and residential greenness has been positively linked to the level of LPA and a variety of positive health outcomes. However, people spend less time in green environments because of urbanization and modern sedentary leisure activities. AIMS: In this population-based study, we investigated the association between objectively measured residential greenness and accelerometry measured physical activity (PA), with a special interest in LPA and gender differences. METHODS: The study was based on the Northern Finland Birth Cohort 1966 (5433 members). Participants filled in a postal questionnaire and underwent clinical examinations and wore a continuous measurement of PA with wrist-worn Polar Active Activity Monitor accelerometers for two weeks. The volume of PA (metabolic equivalent of task or MET) was used to describe the participant's total daily activity (light: 2-3.49 MET; moderate: 3.5-4.99 MET; vigorous: 5-7.99 MET; very vigorous: ≥8 MET). A geographic information system (GIS) was used to assess the features of each individual's residential environment. The normalized difference vegetation index (NDVI) was used for the objective quantification of residential greenness. Multiple linear regression and a generalized additive model (GAM) were used to analyze the association between residential greenness and the amount of PA at different intensity levels. RESULTS: Residential greenness (NDVI) was independently associated with LPA (unadjusted ß = 174; CI = 140, 209) and moderate physical activity (MPA) (unadjusted ß = 75; CI = 48, 101). In the adjusted model, residential greenness was positively and significantly associated with LPA (adjusted ß = 70; CI = 26, 114). In men, residential greenness was positively and significantly associated with LPA (unadjusted ß = 224; CI = 173, 275), MPA (unadjusted ß = 75; CI = 48, 101), and moderate to vigorous physical activity (MVPA) (unadjusted ß = 89; CI = 25, 152). In women, residential greenness was positively related to LPA (unadjusted ß = 142; CI = 96, 188) and inversely associated with MPA (unadjusted ß = -22; CI = -36, -8), vigorous/very vigorous physical activity (VPA/VVPA) (unadjusted ß = -49; CI = -84, -14), and MVPA (unadjusted ß = -71; CI = -113, -29). In the final adjusted models, residential greenness was significantly associated only with the amount of LPA in men (adjusted ß = 140; CI = 75, 204). CONCLUSIONS: Residential greenness was positively associated with LPA in both genders, but the association remained significant after adjustments only in men. Residential greenness may provide a supportive environment for promoting LPA.

Developing the Active Communities Tool to Implement the Community Guide's Built Environment Recommendation for Increasing Physical Activity.

Physical activity is higher in communities that include supportive features for walking and bicycling. In 2016, the Community Preventive Services Task Force released a systematic review of built environment approaches to increase physical activity. The results of the review recommended approaches that combine interventions to improve pedestrian and bicycle transportation systems with land use and environmental design strategies. Because the recommendation was multifaceted, the Centers for Disease Control and Prevention determined that communities could benefit from an assessment tool to address the breadth of the Task Force recommendations. The purpose of this article is to describe the systematic approach used to develop the Active Communities Tool. First, we created and refined a logic model and community theory of change for tool development. Second, we reviewed existing community-based tools and abstracted key elements (item domains, advantages, disadvantages, updates, costs, permissions to use, and psychometrics) from 42 tools. The review indicated that no tool encompassed the breadth of the Community Guide recommendations for communities. Third, we developed a new tool and pilot tested its use with 9 diverse teams with public health and planning expertise. Final revisions followed from pilot team and expert input. The Active Communities Tool comprises 6 modules addressing all 8 interventions recommended by the Task Force. The tool is designed to help cross-sector teams create an action plan for improving community built environments that promote physical activity and may help to monitor progress toward achieving community conditions known to promote physical activity.

An examination of the performance of damaged energy-absorbing end terminals.

OBJECTIVES: Guardrail end terminals are designed to gradually decelerate vehicles during impact and protect vehicle occupants from severe injuries. It has been observed that some in-service end terminals are damaged, and it is unclear if their safety performance is still acceptable. The objectives of this study were to examine the conditions of in-service end terminals, and to evaluate the performance of damaged relative to undamaged end terminals in simulated impacts. METHODS: Common damage patterns of guardrail end terminals were investigated by using post-crash pictures collected from the National Automotive Sampling System-Crashworthiness Data System (NASS-CDS). Conditions of in-service end terminals mounted along roads in portions of six U.S. states were examined by using a sample from the second Strategic Highway Research Program-Roadway Information Database (SHRP2-RID). Finite Element (FE) models of two minorly and three severely damaged ET-Plus systems, a commonly used energy-absorbing guardrail end terminal along U.S. roads, were developed. To evaluate the performance of the damaged ET-Plus systems, we performed impact simulations with vehicle-to-damaged ET-Plus models according to the National Cooperative Highway Research Program (NCHRP) 350, test conditions 3-30. RESULTS: Of the 1000 in-service end terminal cases we investigated, 73% were undamaged, 18% had minor damage, and 8% had major damage. Increases in the average vehicle deceleration rates, maximum vehicle yaw angles, and vehicle local deformations were observed in simulated impacts with damaged ET-Plus end terminals relative to impacts with undamaged ET-Plus end terminals. For one damaged ET-Plus, a secondary collision was observed. Overall, we found that the damaged end terminals usually increased collision severity when compared with undamaged end terminals. CONCLUSIONS: The findings of this study point out the need for in-service performance evaluations and proper maintenance and repair practices of end terminals. The simulation models developed in this study could be further employed to investigate device performance in crash situations that are physically impractical to test and investigate the effects of site characteristics on device performance. The simulation models could also supplement crash tests to certify new hardware designs.

Prediction of pedestrian-vehicle conflicts at signalized intersections based on long short-term memory neural network.

Pedestrian protection is an important component of road safety. Intersections are dangerous locations for pedestrians with mixed traffic. This paper aims to predict potential traffic conflicts between pedestrians and vehicles at signalized intersections. Using detection and tracking techniques in computer vision, pedestrians' and vehicles' features are extracted from video data. An LSTM (Long Short-term Memory) neural network is proposed to predict the pedestrian-vehicle conflicts 2 s ahead. The established model reaches an accuracy of 88.5 % at one signalized intersection. It is further tested at a new intersection, reaching the accuracy of 84.9 %, while the new data merely takes up 30 % of the training data set. This indicates that the proposed model is promising to be implemented at different locations. Moreover, the proposed model can also be applied to develop collision warning systems under the Connected Vehicles' environment.

Benchmarking road safety development across OECD countries: An empirical analysis for a decade.

Benchmarking performance, monitoring progress and then recalibrating interventions is widely recognized as a valuable process for achieving continuous improvement in road safety. In this study, a systematic and effective methodology, IV-VIKOR with FNBC, is developed to perform the benchmarking of road safety development in an integrative manner for OECD (Organisation for Economic Co-operation and Development) countries. Linking to other methods and measures as the references, 36 OECD Member countries are ranked and grouped into several classes based on their overall achievement regarding road safety from the past decade (2009-2018). This provides government officials and policymakers, across the OECD Member countries, with a flexible tool to comprehensively benchmark road safety development. Providing the ability to identify delays in action plan implementations and proactively redistribute resources toward more effective measures where required. Such a tool can also serve to increase political will and stakeholder accountabilities, at the highest level of government and the private sector for all OECD members: Thereby keeping the implementation of action plans on schedule. It helps OECD Member countries to establish the capacity for sustainable safety management; supporting them in developing future strategies and reforms to create better policies for better lives.

Examining the effect of road horizontal alignment on the speed of semi-automated vehicles.

The novel semi-autonomous vehicles are becoming a reality in our roads, being a very important technological advance with promising operational and safety improvements. However, road infrastructure must be ready to host them. The technologies of these driving automation systems require certain road conditions that are not always fulfilled, causing the systems to fail. These failures generally transfer negotiation control to drivers, which may induce a crash if they were not aware of road and traffic conditions. This research analyses how ready the road horizontal alignment is for existing semi-autonomous systems. A Level 2 vehicle has been tested on many different horizontal curves, finding a strong relationship between the maximum speed that the autonomous system can attain and the curve geometry. This maximum speed is proposed as a new concept (automated speed) and has been found to be lower than the design, operating and posted speeds in many cases. Another new concept - automated driving consistency - arises, as the difference between automated and operating speeds. The related inconsistencies can be addressed with the new concept of Level of Service for Automated Driving (LOSAD), which summarizes how ready a corridor is for a certain driving automation system. This parameter should be determined - further certified - for any homogeneous road segment, and later informed to drivers.

Ecological study of playground space and physical activity among primary school children.

OBJECTIVES: To examine the relationship between school playground size and total physical activity (PA), fitness and fundamental movement skills (FMS) of primary school students. DESIGN: Cross-sectional ecological analysis. SETTING: 43 primary schools in New South Wales, Australia. PARTICIPANTS: Data were from 5238 students, aged 5 to 12 years, participating in the Schools Physical Activity and Nutrition Survey. OUTCOME MEASURES: Self (for age ≥11 years) and parent (for age <11 years) report of PA (meeting PA recommendations and number of days meeting recommendations), objectively measured FMS and cardiorespiratory and muscular fitness. RESULTS: Associations between playground space and measures of PA and fitness were mostly non-linear and moderated by loose equipment. Students in schools with no loose equipment showed a weak association between space and meeting PA recommendations (self-report). In schools with equipment, students' predicted probability of meeting PA recommendations increased sharply between 15 m2 and 25 m2 per student from 0.04 (95% CI: 0.01 to 0.08) to 0.30 (95% CI: 0.14 to 0.46), but at 30 m2 returned to levels comparable to students in schools with no equipment (0.18, 95% CI: 0.07 to 0.28). For cardiorespiratory fitness, in schools with no loose equipment, probabilities for being in the healthy cardiovascular fitness zone varied between 0.66 and 0.77, showing no consistent trend. Students in schools with loose equipment had a predicted probability of being in the healthy fitness zone of 0.56 (95% CI: 0.41 to 0.71) at 15 m2 per student, which rose to 0.75 (95% CI: 0.63 to 0.86) at 20 m2 per student. There was no relationship between space and FMS. CONCLUSIONS: School space guidelines need to incorporate sufficient playground space for students. Our study provides evidence supporting better PA outcomes with increasing space up to 25 m2 per student, and access to loose equipment, however further research is required to determine precise thresholds for minimum space. Intersectoral planning and cooperation is required to meet the needs of growing school populations.

Safety and operational impact of connected vehicles' lane configuration on freeway facilities with managed lanes.

Managed lanes (MLs) have been implemented as a vital strategy for traffic safety and management improvements. Previous studies involving MLs didn't examine the impact of connected vehicles' (CVs) lane configuration on freeway facilities with managed toll lanes. CVs are quickly expanding in the transportation industry and are among the most recent promising developments in traffic and safety engineering. In this study, several scenarios were tested using microscopic traffic simulation to determine the optimal CV lane configuration strategies while taking into consideration the market penetration rate (MPR%) of CVs and traffic conditions (i.e., peak, off-peak). Both safety (i.e., conflict frequency, conflict reduction) and operational (i.e., average speed, average delay) performance measures were included in the analyses. A Negative Binomial model was developed for investigating the factors that affect the safety measures. Tobit models were used to evaluate traffic operation. The results of the safety and operational analyses suggested that an MPR% between 10 % and 30 % was recommended when the CVs were only allowed in MLs. By converting one of the general-purpose lanes (GPLs) to a managed lane, the MPR% could reach 60 %. It was also concluded that restricting CVs to only the CV lane was not recommended. Lastly, the findings suggested that by allowing CVs to use all the lanes in the network (MLs, GPLs and CV lane), the optimal MPR% could reach between 70 % and 100 %. This study has major implications for improving MLs by recommending the optimal CV lane configuration and market penetration rate for each design.

Effects of built environment on bicycle wrong Way riding behavior: A data-driven approach.

Bicycle wrong way riding (WWR) is a dangerous and often neglected behavior that engenders threats to traffic safety. Owing to the lack of exposure data, the detection of WWR and its relationship with the built environment (BE) factors remain unclear. Accordingly, this study fills the research gaps by proposing a WWR detection framework based on bike-sharing trajectories collected from Chengdu, China. Moreover, this study adopts Negative Binomial-based Additive Decision Tree to investigate the impacts of built environment on WWR frequencies. Results reveal that (1) WWR distribution is unaffected by different periods in a day; (2) road length is more influential than road level and road direction in WWR occurrence; (3) company, bus stop, subway station, residence, and catering facility are primary contributors affecting WWR behavior during peak hours, whereas education becomes an emerging influential variable during nonpeak hours; and most importantly, (4) these variables clearly present non-linear effects on the WWR frequencies. Therefore, geographically differentiated policies should be adopted for bicycle safety improvement.

Revisiting freeway single tunnel crash characteristics analysis: A six-zone analytic approach.

Considerable studies have been conducted to investigate the tunnels' traffic safety. However, the entrance and exit parts of a tunnel are mostly considered symmetrical in previous studies, and the different lengths (long, medium, and short) of tunnels have not been separately studied. This study aims to investigate the characteristics of traffic crashes in freeway single tunnels by separately considering the entrance and exit of the tunnel as well as the different lengths of tunnels. A six-zone approach is proposed, and the data from 156 single tunnels in Hunan province, China, are applied for safety analysis. The crash rate, crash type, and contributing crash factors are compared between the conventional four-zone approach and the proposed method, and the three types of tunnels with different lengths are also compared for in-depth analysis. Results show that the proposed six-zone method provides a better understanding of the tunnels crash characteristics. The most crash-prone zones for long, medium, and short tunnels are the mid-zone, the entrance zone, and the access zone, respectively. Furthermore, at the tunnel entrance, drivers usually fail to maintain safe distance, which results in the high proportion of rear-end crashes, while at the tunnel exit, they do speeding and improper lane change that increases the risk of sideswipe, rollover, and collision with fixed objects. The study also discusses the crash occurrence mechanism for different types of tunnels. Findings of this study shed some light on the engineering and policy implications for improving traffic safety of the freeway tunnels.

The built environment and obesity: You are where you live.

BACKGROUND: Obesity has continued to rise in prevalence globally. Its association with many chronic diseases is posing a large threat to public health. OBJECTIVE: The aim of this article is to examine briefly the nature and complexity of the problem of obesity and to present evidence about the elements of the built environment that are associated with obesity. DISCUSSION: Management of obesity is far more complex than just requiring people to 'eat less and exercise more'. Social and environmental drivers are known to influence an individual's decisions about healthy behaviour. Some elements of the built environment shown to be associated with obesity are urban sprawl, urban design, land-use mix, transport systems, access to and type of food outlets, and building design. This evidence augments the current individual clinical management of obesity by providing guidance to advocates of health and regulators so they are able to design and create environments that foster healthy eating and personal activity.

Investigating rear-end collision avoidance behavior under varied foggy weather conditions: A study using advanced driving simulator and survival analysis.

Previous studies have focused on the impact of visibility level on drivers' behavior and their safety in foggy weather. However, other important environmental factors such as road alignment have not been considered. This paper aims to propose a methodology in investigating rear-end collision avoidance behavior under varied foggy conditions, with focusing on changes in visibility and road alignment in this study. A driving simulator experiment with a mixed 2 × 4 × 6 factor design was conducted using an advanced high-fidelity driving simulator. The design matrix includes two safety-critical conditions, four visibility conditions, and six road alignment situations (in terms of the road curve and slope). Behavior variables from different dimensions were identified and compared under varied conditions. To estimate the safety of drivers, a time-based measurement, speed reduction time, is selected among the variables as a measure of safety. The survival analysis approach was introduced to model the relationship between environmental factors and driver safety, using speed reduction time as the survival time. Both the Kaplan-Meier method and the COX model were applied and compared. Results generally suggest that reduced visibility leads to more dangerous rear-end collision avoidance behavior from different aspects. Though findings are mixed regarding the road alignment, the impact of the road alignment was found to be significant. Interestingly, conditions of downward slope were found to be safer. Overall, the COX model outperformed the Kaplan-Meier method in understanding the impact of environmental factors, and it can be applied to investigate other contributing factors for freeway safety under foggy weather conditions.

Transferability of safety performance functions and hotspot identification for freeways of the United States and China.

Safety performance function (SPF) has been a vital tool in traffic safety evaluation including finding contributing factors to crashes, identifying hotspots, and assessing safety effects of countermeasures. In the United States (U.S.), the Highway Safety Manual provides a number of SPFs for a variety of road facilities. Due to the limited availability of traffic data in many regions, the transferability of SPFs has been an important topic in traffic safety analysis and has been evaluated by several studies. Nevertheless, the international transferability of freeway SPFs and the applicability of transferred SPFs on hotspot identification has been rarely investigated. Based on data from two Chinese cities, Shanghai and Suzhou, and three U.S. states, Texas, New York and Florida, this study analyzes the transferability of freeway SPFs between Chinese and U.S. regions. These SPFs are then transferred to the other country and their performance on hotspot identification is investigated. SPFs were developed in the frameworks of Poisson, Poisson-lognormal and negative binomial regressions for the five localities separately, and were calibrated using the calibration functions before being transferred. Without calibration, the poor model transferability was found between the two countries, while after calibration, the transferred SPFs between Shanghai/Suzhou and Texas/New York showed satisfactory performance on both model fitting and hotspot identification. However, the transferability of SPFs between Florida and the Chinese cities turned out to be unsatisfactory regardless of whether being calibrated or not, which was attributable to the considerable difference in traffic flow. The findings of this study are expected to be a good reference for researchers and practitioners who want to understand the transferability and applicability of SPFs in the international context.