Environmental characteristics associated with pedestrian-motor vehicle collisions in Denver, Colorado

Prevalence of indications of alcohol and drug use among patients treated for injurious falls by Emergency Medical Services

Objective

To describe the distribution of alcohol and drug involvement in injurious falls by location and subtype of fall.

Methods

Using the 2019 National Emergency Medical Services Information System (NEMSIS) dataset we identified 1,854,909 patients injured from falls requiring an Emergency Medical Services (EMS) response and determined the fall location (e.g. indoors or on street/sidewalk) and the EMS clinician's notation of alcohol or drug involvement. We analyzed substance involvement by fall subtype, location of fall and patient demographics.

Results

Overall, for 7.4% of injurious falls there was a notation of substance use: 6.5% for alcohol alone, 0.6% for drugs and 0.3% for alcohol and drugs. 21.2% of falls that occurred on a street or sidewalk had a notation of substance use; alcohol use alone for 18.5% of falls, drugs alone for 1.7% of falls and alcohol and drugs for 0.9% of falls. Substance use prevalence was highest, at 30.3%, in the age group 21 to 64 years, for falls occurring on streets and sidewalks, without syncope or heat illness as contributing factors; alcohol use alone for 26.3%, drugs alone for 2.6%, and alcohol and drugs for 1.4%. Reported substance use involvement was more frequent for men compared to women for each location type.

Conclusions

Overall, 1-in-5 injurious falls on streets and sidewalks and requiring EMS attention involved substance use, and these numbers likely underestimate the true burden. As cities seek to expand nightlife districts, design strategies to protect pedestrians from falls should be enacted.

Clinical Trauma Severity of Indoor and Outdoor Injurious Falls Requiring Emergency Medical Service Response

Background

Injurious falls represent a significant public health burden. Research and polices have primarily focused on falls occurring indoors despite evidence that outdoor falls account for 47-58% of all falls requiring some medical attention. This study compared the clinical trauma severity of indoor versus outdoor injurious falls requiring Emergency Medical Services (EMS) response.

Methods

Using the 2019 National Emergency Medical Services Information System (NEMSIS) dataset, we identified the location of patients injured from falls that required EMS response. We classified injury severity using 1) the Revised Trauma Score for Triage (T-RTS): ≤ 11 indicated the need for transport to a Trauma Center; 2) Glasgow Coma Scale (GCS): ≤8 and 9-12 indicated moderate and severe neurologic injury; and 3) patient clinical acuity by EMS: Dead, Critical, Emergent, Low.

Results

Of 1,854,909 encounters for patients with injurious falls, the vast majority occurred indoors (n=1,596,860) compared to outdoors (n=152,994). The proportions of patients with moderate or severe GCS scores, were comparable between those with indoor falls (3.0%) and with outdoor falls on streets or sidewalks (3.8%), T-RTS scores indicating need for transport to a Trauma Center (5.2% vs 5.9%) and EMS acuity rated as Emergent or Critical (27.7% vs 27.1%).Injurious falls were more severe among male patients compared to females: and males injured by falling on streets or sidewalks had higher percentages for moderate or severe GCS scores (4.8% vs 3.6%) and T-RTS scores indicating the need for transport to a Trauma Center (7.3% vs 6.5%) compared to indoor falls. Young and middle-aged patients whose injurious falls occurred on streets or sidewalks were more likely to have a T-RTS score indicating the need for Trauma Center care compared to indoor falls among this subgroup. Yet older patients injured by falling indoors were more likely to have a T-RTS score indicating the need for Trauma Center than older patients who fell on streets or sidewalks.

Conclusions

There was a similar proportion of patients with severe injurious falls that occurred indoors and on streets or sidewalks. These findings suggest the need to determine outdoor environmental risks for outdoor falls to support location-specific interventions.

A spatiotemporal deep learning approach for pedestrian crash risk prediction based on POI trip characteristics and pedestrian exposure intensity

Pedestrians represent a population of vulnerable road users who are directly exposed to complex traffic conditions, thereby increasing their risk of injury or fatality. This study first constructed a multidimensional indicator to quantify pedestrian exposure, considering factors such as Point of Interest (POI) attributes, POI intensity, traffic volume, and pedestrian walkability. Following risk interpolation and feature engineering, a comprehensive data source for risk prediction was formed. Finally, based on risk factors, the VT-NET deep learning network model was proposed, integrating the algorithmic characteristics of the VGG16 deep convolutional neural network and the Transformer deep learning network. The model involved training non-temporal features and temporal features separately. The training dataset incorporated features such as weather conditions, exposure intensity, socioeconomic factors, and the built environment. By employing different training methods for different types of causative feature variables, the VT-NET model analyzed changes in risk features and separately trained temporal and non-temporal risk variables. It was used to generate spatiotemporal grid-level predictions of crash risk across four spatiotemporal scales. The performance of the VT-NET model was assessed, revealing its efficacy in predicting pedestrian crash risks across the study area. The results indicated that areas with concentrated crash risks are primarily located in the city center and persist for several hours. These high-risk areas dissipate during the late night and early morning hours. High-risk areas were also found to cluster in the city center; this clustering behavior was more prominent during weekends compared to weekdays and coincided with commercial zones, public spaces, and educational and medical facilities.

Pedestrian Safety in Compact and Mixed-Use Urban Environments: Evaluation of 5D Measures on Pedestrian Crashes

This study examined the impact of density, diversity, design, distance to transit, and destination accessibility, five measures, known as the 5Ds, that characterize the built environment, on pedestrian–vehicle crashes in Seoul, Korea. Using spatial analysis based on 500-m grid cells, this study employed negative binomial regression models on the frequencies of three specific types of pedestrian–vehicle crashes: crashes causing death, major injury, and minor injury to pedestrians. Analysis shows that compact and mixed-use urban environments represented by 5D measures have mixed effects on pedestrian safety. Trade-off effects are found between a higher risk for all types of pedestrian crashes, and a lower risk for fatal pedestrian crashes in 5D urban environments. As a design variable, a higher number of intersections is more likely to increase some types of pedestrian crashes, including fatal crashes, a finding which warrants policy attention to promote pedestrian safety near intersection areas. This study also confirms an urgent need to secure the travel safety of pedestrians near public transit stations due to the higher risk of pedestrian crashes near such facilities. Various destinations, such as retail stores, traditional markets, and hospitals, are associated with pedestrian crashes. Pedestrian safety measures should be implemented to reduce the likelihood of pedestrian crashes near major destination facilities.

Towards activity-based exposure measures in spatial analysis of pedestrian-motor vehicle crashes

BACKGROUND

Although numerous efforts have been devoted to exploring the effects of area-wide factors on the frequency of pedestrian crashes in neighborhoods over the past two decades, existing studies have largely failed to provide a full picture of the factors that contribute to the incidence of zonal pedestrian crashes, due to the unavailability of reliable exposure data and use of less sound analytical methods.

METHODS

Based on a crowdsourced dataset in Hong Kong, we first proposed a procedure to extract pedestrian trajectories from travel-diary survey data. We then aggregated these data to 209 neighborhoods and developed a Bayesian spatially varying coefficients model to investigate the spatially non-stationary relationships between the number of pedestrian-motor vehicle (PMV) crashes and related risk factors. To dissect the role of pedestrian exposure, the estimated coefficients of models with population, walking trips, walking time, and walking distance as the measure of pedestrian exposure were presented and compared.

RESULTS

Our results indicated substantial inconsistencies in the effects of several risk factors between the models of population and activity-based exposure measures. The model using walking trips as the measure of pedestrian exposure had the best goodness-of-fit. We also provided new insights that in addition to the unstructured variability, heterogeneity in the effects of explanatory variables on the frequency of PMV crashes could also arise from the spatially correlated effects. After adjusting for vehicle volume and pedestrian activity, road density, intersection density, bus stop density, and the number of parking lots were found to be positively associated with PMV crash frequency, whereas the percentage of motorways and median monthly income had negative associations with the risk of PMV crashes.

CONCLUSIONS

The use of population or population density as a surrogate for pedestrian exposure when modeling the frequency of zonal pedestrian crashes is expected to produce biased estimations and invalid inferences. Spatial heterogeneity should also not be negligible when modeling pedestrian crashes involving contiguous spatial units.

Qualitative Field Observation of Pedestrian Injury Hotspots: A Mixed-Methods Approach for Developing Built- and Socioeconomic-Environmental Risk Signatures

Road traffic injuries constitute a significant global health burden; the World Health Organization estimates that they result in 1.35 million deaths annually. While most pedestrian injury studies rely predominantly on statistical modelling, this paper argues for a mixed-methods approach combining spatial analysis, environmental scans, and local knowledge for assessing environmental risk factors. Using data from the Nova Scotia Trauma Registry, severe pedestrian injury cases and ten corresponding hotspots were mapped across the Halifax Regional Municipality. Using qualitative observation, quantitative environmental scans, and a socioeconomic deprivation index, we assessed hotspots over three years to identify key social- and built-environmental correlates. Injuries occurred in a range of settings; however, clear patterns were not observed based on land use, age, or socio-economic status (SES) alone. Three hotspots revealed an association between elevated pedestrian injury and a pattern of geographic, environmental, and socio-economic factors: low- to middle-SES housing separated from a roadside attraction by several lanes of traffic, and blind hills/bends. An additional generalized scenario was constructed representing common risk factors across all hotspots. This study is unique in that it moves beyond individual measures (e.g., statistical, environmental scans, or geographic information systems (GIS) mapping) to combine all three methods toward identifying environmental features associated with pedestrian motor vehicle crashes (PMVC).

Geographical distribution of at fault drivers involved in fatal traffic collisions in Tehran, Iran

OBJECTIVES

According to Traffic Police, about 35% of deaths and more than 50% of injuries caused by traffic collision in the roads of Tehran are among drivers and car occupants. This study was conducted to determine areas with the highest number of traffic collisions and perform spatial analysis of traffic collisions involving drivers in Tehran during April 2014 to March 2017.

METHODS

The present study was a cross-sectional and descriptive-analytic research. In this study, all traffic collision that driver was accounted (100 percent or less) for crash occurrence which resulted in the death of at least one person (driver, pedestrian or passenger) were included in the analyses. Geographic information system software was used to show spatial distribution of events from zoning maps. Moran index was used in the mathematical analysis in order to determine the distribution pattern of the events from and Getis-Ord G statistics was applied to analyze the hot spots (high risk points).

RESULTS

A total number of 519 traffic collisions were investigated in this study. Moreover, 283 cases (54.5%) of the incidents took place in direct routes and 236 cases (45.5%) occurred at intersections. The most frequent events were in the region 4 (57 cases) and the least frequent events were reported in the region 10 (6 cases). Moran statistics show that the distribution of the studied events significantly follows the cluster pattern (p<0.001).

CONCLUSIONS

The northeastern and northwest margins of Tehran are the most prone areas for drivers involved with traffic collisions leading to death. Most traffic collisions leading to death take place at highways located at the entrance and exit points of Tehran and highways in regions 2 and 5.

Spatial analysis of driving accidents leading to deaths related to motorcyclists in Tehran

PURPOSE

Traffic accidents are one of the main causes of death and disability, causing annual deaths of 1.23 million and tens of millions injured people worldwide. Meanwhile, a significant proportion of the deaths and injuries caused by traffic accidents occur among motorcyclists. According to the world health organization's 2015 report, about 25% of deaths from traffic accidents occur in motorists. In Iran, a significant proportion of deaths and injuries result from traffic accidents among motorcyclists, especially in passages within the cities. According to traffic police, about 25% of deaths and 50% of injuries in traffic accidents of Tehran are reported among motorcyclists. Therefore, due to the importance of this issue, the spatial factors influencing the incidence of motorcycle-related accidents in Tehran were investigated using the geographic information system.

METHODS

The present work was a cross-sectional and descriptive analysis study. The data necessary for the study were extracted from Tehran traffic police as well as municipality databases. Zoning maps were used to display the distribution of events. In the analytical investigation, Moran index was used to determine the distribution pattern of the events, while Getis-Ord G * statistics were applied to analyze hot spots. To investigate the role of regional and environmental factors in the frequency of traffic accidents related to motorcyclists in geographic units (Tehran 22 districts), Poisson regression and negative binomial models were used. The geographically weighted regression (GWR) model was used to analyze the relationship between environmental factors and the location of these events. Statistical analyses were performed using SPSS, STATA, ARC-GIS and GWR software.

RESULTS

The southern and eastern margins of Tehran are the most vulnerable areas in terms of deaths related to traffic accidents of motorcyclists. Highways are considered the location of most traffic accidents which lead to death of motorcyclists. Getis-Ord General G * (p < 0.04) indicates that the distribution of high-risk points is statistically significant. The final model showed that in Tehran, the association of different variables including demographic characteristics, pathways network and type of land use with the number of accidents in geographic units was statistically significant. The spatial distribution of traffic accidents leading to deaths of motorcyclists in the center of Tehran varies considerably with changes in population density, length of highways, volume of traffic, and land use in different parts.

CONCLUSION

Most of the traffic accidents leading to deaths of motorcyclists occur in highways. Various environmental variables play a role in determining the distribution pattern of these types of events. Through proper traffic management, controlling environmental risk factors and training people the safety of motorcyclists in Tehran can be improved.

Increased Risk of Traffic Injury After a Cerebrovascular Event

Background and Purpose- We aimed to determine the long-term risks of a motor vehicle collision after a cerebrovascular event and whether the risks were similar after left- or right-hemispheric events. Methods- We used a population-based registry to identify patients diagnosed with a transient ischemic attack or stroke (hemorrhagic or ischemic) between 2003 and 2013 in Ontario, Canada. Hemispheric laterality was determined using radiological and clinical findings. We identified subsequent serious injuries involving the patient as a driver using linked administrative data. Secondary outcomes included serious injuries involving the patient as a pedestrian, as a passenger, or other traumatic events (fall, fracture, ankle sprain). We used proportional hazard models accounting for death as a competing risk to test the association of hemispheric laterality and outcomes with and without adjustment for age, sex, discharge modified Rankin Scale score, home location, and prior driving record. Patients were followed through to 2017. Results- Among 26 144 patients with hemispheric cerebrovascular events, 377 subsequent serious traffic injuries as a driver (2.2 per 1000 person-year) were identified over a median follow-up of 6.4 person-years. The rate did not differ by laterality (adjusted hazard ratio, 1.00; 95% CI, 0.82-1.23). The risk of a serious traffic injury as a pedestrian was significantly higher after a right-sided than left-sided event (adjusted hazard ratio, 1.27; 95% CI, 1.02-1.58). Subsequent risks for other traumatic injuries did not differ by laterality of cerebrovascular event. Conclusions- The risk of a serious traffic injury as a pedestrian is substantially higher after a right-hemispheric cerebrovascular event compared with a left-sided event. Walking should be promoted for exercise in survivors of a stroke or transient ischemic attack, but these vulnerable road users may benefit from additional poststroke rehabilitation to optimize safety.

Bayesian approach to model pedestrian crashes at signalized intersections with measurement errors in exposure

This study intended to identify the potential factors contributing to the occurrence of pedestrian crashes at signalized intersections in a densely populated city, based on a comprehensive dataset of 898 pedestrian crashes at 262 signalized intersections during 2010-2012 in Hong Kong. The detailed geometric design, traffic characteristics, signal control, built environment, along with the vehicle and pedestrian volumes were elaborately collected. A Bayesian measurement errors model was introduced as an alternative method to explicitly account for the uncertainties in volume data. To highlight the role played by exposure, models with and without pedestrian volume were estimated and compared. The results indicated that the omission of pedestrian volume in pedestrian crash frequency models would lead to reduced goodness-of-fit, biased parameter estimates, and incorrect inferences. Our empirical analysis demonstrated the existence of moderate uncertainties in pedestrian and vehicle volumes. Six variables were found to have a significant association with the number of pedestrian crashes at signalized intersections. The number of crossing pedestrians, the number of passing vehicles, the presence of curb parking, and the presence of ground-floor shops were positively related with pedestrian crash frequency, whereas the presence of playgrounds near intersections had a negative effect on pedestrian crash occurrences. Specifically, the presence of exclusive pedestrian signals for all crosswalks was found to significantly reduce the risk of pedestrian crashes by 43%. The present study is expected to shed more light on a deeper understanding of the environmental determinants of pedestrian crashes.

RETRACTED ARTICLE: Effective environmental factors on geographical distribution of traffic accidents on pedestrians, downtown of Tehran City

The following article has been retracted from publication in the Taylor & Francis journalInternational Journal of Injury Control and Safety Promotion:Ali Moradi, 'Effective environmental factors on geographical distribution of traffic accidents on pedestrians, downtown of Tehran City', International Journal of Injury Control and Safety Promotion, https://doi.org/10.1080/17457300.2018.1431933. Version of Record published online 20 February 2018.This article has already been published in the International Journal of Critical Illness and Injury Science.

Effective environmental factors on geographical distribution of traffic accidents on pedestrians, downtown Tehran city

Introduction:

In most countries, occurrence of traffic causalities is high in pedestrians. The aim of this study is to geographically analyze the traffic casualties in pedestrians in downtown Tehran city.

Methods:

The study population consisted of traffic injury accidents in pedestrians occurred during 2015 in Tehran city. Data were extracted from offices of traffic police and municipality. For analysis of environmental factors and site of accidents, ordinary least square regression models and geographically weighted regression were used. Fitness and performance of models were checked using the Akaike information criteria, Bayesian information criteria, deviance, and adjusted R².

Results:

Totally, 514 accidents were included in this study. Of them, site of accidents was arterial streets in 370 (71.9%) cases, collector streets in 133 cases (25.2%), and highways in 11 cases (2.1%). Geographical units of traffic accidents in pedestrians had statistically significant relationship with a number of bus stations, number of crossroads, and recreational areas.

Conclusion:

Distribution of injury traffic accidents in pedestrians is different in downtown Tehran city. Neighborhoods close to markets are considered as most dangerous neighborhoods for injury traffic accidents. Different environmental factors are involved in determining the distribution of these accidents. The health of pedestrians in Tehran city can be improved by proper traffic management, control of environmental factors, and educational programs.

Exploring spatial autocorrelation of traffic crashes based on severity

As a developing country, Iran has one of the highest crash-related deaths, with a typical rate of 15.6 cases in every 100 thousand people. This paper is aimed to find the potential temporal and spatial patterns of road crashes aggregated at traffic analysis zonal (TAZ) level in urban environments. Localization pattern and hotspot distribution were examined using geo-information approach to find out the impact of spatial/temporal dimensions on the emergence of such patterns. The spatial clustering of crashes and hotspots were assessed using spatial autocorrelation methods such as the Moran's I and Getis-Ord Gi* index. Comap was used for comparing clusters in three attributes: the time of occurrence, severity, and location. The analysis of the annually crash frequencies aggregated in 156 TAZ in Shiraz; from 2010 to 2014, Iran showed that both Moran's I method and Getis-Ord Gi* statistics produced significant clustering of crash patterns. While crashes emerged a clustered pattern, comparison of the spatio-temporal separations showed an accidental spread in distinct categories. The local governmental agencies can use the outcomes to adopt more effective strategies for traffic safety planning and management.

Spatial Factors Affecting the Frequency of Pedestrian Traffic Crashes: A Systematic Review

Context

Considering the importance of pedestrian traffic crashes and the role of environmental factors in the frequency of crashes, this paper aimed to review the published evidence and synthesize the results of related studies for the associations between environmental factors and distribution of pedestrian-vehicular traffic crashes.

Evidence Acquisition

We searched all epidemiological studies from 1966 to 2015 in electronic databases. We found 2,828 studies. Only 15 observational studies out of these studies met the inclusion criteria of the study. The quality of the included studies was assessed using the strengthening the reporting of observational studies in epidemiology (STROBE) checklist.

Results

A review of the studies showed significant correlations between a large number of spatial variables including student population and the number of schools, population density, traffic volume, roadway density, socio-economic status, number of intersections, and the pedestrian volume and the dependent variable of the frequency of pedestrian traffic crashes. In the studies, some spatial factors that play an important role in determining the frequency of pedestrian traffic crashes, such as facilities for increasing the pedestrians’ safety were ignored.

Conclusions

It is proposed that the needed research be conducted at national and regional levels in coordination and cooperation with international organizations active in the field of traffic crashes in various parts of the world, especially in Asian, African and Latin American developing countries, where a greater proportion of pedestrian traffic crashes occur.

Spatial analysis to identify high risk areas for traffic crashes resulting in death of pedestrians in Tehran

Background: More than 20% of deaths from traffic crashes are related to pedestrians. This figure in Tehran, the capital of Iran, reaches to 40%. This study aimed to determine the high-risk areas and spatially analyze the traffic crashes, causing death to pedestrians in Tehran. Methods: Mapping was used to display the distribution of the crashes. Determining the distribution pattern of crashes and the hot spots/ low-risk areas were done, using Moran's I index and Getis-Ord G, respectively. Results: A total of 198 crashes were studied; 92 of which, (46.4%) occurred in 2013 to 2014 and other 106 cases (63.6%) occurred in 2014 to 2015. The highest and the lowest frequency of crashes was related to January (26 cases) and June (10 cases), respectively. One hundred fifty- eight cases (79.8%) of crashes occurred in Tehran highways. Moran's index showed that the studied traffic crashes had a cluster distribution (p<0.001). Getis- Ord General G index indicated that the distribution of hot and cold spots of the studied crashes was statistically significant (p<0.001). Conclusion: The majority of traffic crashes causing death to pedestrians occurred in highways located in the main entrances and exits of Tehran. Given the important role of environmental factors in the occurrence of traffic crashes related to pedestrians, identification of these factors requires more studies with casual inferences.

Alcohol intoxication in non-motorised road trauma

OBJECTIVE

To determine the proportion of non-motorised road users involved in road traffic crashes that presents to hospital intoxicated.

METHODS

We undertook a retrospective cohort study using data collected from the Alfred Trauma Registry. All patients presenting to an adult major trauma centre in Victoria, Australia from July 2009 to June 2014 who were involved in a road traffic crash as a non-motorised road user - pedestrians, pedal-cyclists, non-motorised scooter users, horse riders - were included. Patients who had a blood alcohol measurement were included, and intoxication was defined as a blood alcohol concentration ≥0.05 g/100 mL.

RESULTS

There were 1323 patients included for analysis with data on presenting blood alcohol concentration. Alcohol was detected in 248 (18.7%; 95% CI: 16.7-20.9) patients, whereas 211 (15.9%; 95% CI: 14.1-18.0) were intoxicated. Among all included pedestrians, 161 (24.7%) were intoxicated; among all included pedal-cyclists, 47 (7.3%) were intoxicated. Intoxicated patients were significantly younger, and a higher proportion were males and more likely to present after hours and on public holidays (P < 0.01). Survival to hospital discharge and inpatient rehabilitation requirements were similar among intoxicated and non-intoxicated patients.

CONCLUSIONS

Intoxication was common among non-motorised road users, and the proportion of intoxicated patients in this subgroup appears unchanged over time despite public awareness programmes. The true burden of intoxication in non-motorised road users remains unknown because of a lack of routine testing. Legislation directed at testing for intoxication of non-motorised users and introduction of penalties should be considered to improve safety of all road users.

Spatial analysis of the association of alcohol outlets and alcohol-related pedestrian/bicyclist injuries in New York City

BACKGROUND

Pedestrian and bicyclist injury is an important public health issue. The retail environment, particularly the presence of alcohol outlets, may contribute the the risk of pedestrian or bicyclist injury, but this association is poorly understood.

METHODS

This study quantifies the spatial risk of alcohol-related pedestrian injury in New York City at the census tract level over a recent 10-year period using a Bayesian hierarchical spatial regression model with Integrated Nested Laplace approximations. The analysis measures local risk, and estimates the association between the presence of alcohol outlets in a census tract and alcohol-involved pedestrian/bicyclist injury after controlling for social, economic and traffic-related variables.

RESULTS

Holding all other covariates to zero and adjusting for both random and spatial variation, the presence of at least one alcohol outlet in a census tract increased the risk of a pedestrian or bicyclist being struck by a car by 47 % (IDR = 1.47, 95 % Credible Interval (CrI) 1.13, 1.91).

CONCLUSIONS

The presence of one or more alcohol outlets in a census tract in an urban environment increases the risk of bicyclist/pedestrian injury in important and meaningful ways. Identifying areas of increased risk due to alcohol allows the targeting of interventions to prevent and control alcohol-related pedestrian and bicyclist injuries.

Installation of speed humps and pedestrian-motor vehicle collisions in Toronto, Canada: a quasi-experimental study

Background

Evidence related to the effectiveness of speed humps on reducing pedestrian-motor vehicle collisions (PMVC) has been conflicting. The purpose of this study was to determine the association between speed hump installation and changes in PMVC rates in Toronto, Canada.

Methods

Speed humps were mapped along with police-reported pedestrian collisions from 2000–2011 and built environment roadway characteristics. A quasi-experimental study identified collision counts before and after speed hump installation, modeled using repeated measures Poisson regression adjusted for season and roadway characteristics. Stratified analyses were conducted by age group and injury severity.

Results

There were 27,827 PMVC, with 1344 collisions along 409 roadways with speed humps. PMVC incidence rates/meters of road/month decreased after installation of speed humps (IRR 0.78 95 % CI 0.66, 0.91). Winter, collector roads (versus local), pre-amalgamated city centre and increased land use mix were associated with more collisions. The association between speed humps and PMVC rates decreased more for children (IRR 0.57, 95 % CI 0.41, 0.79) than for adults (IRR 0.80, 95 % CI 0.68, 0.95).

Conclusions

Speed humps are an easily replicated method of traffic calming which have a significant protective effect on PMVC on the roadways where they are installed, particularly for children. There is a need for an area-wide analysis to determine the effects of the installation of speed humps to ensure that PMVC are not being displaced to surrounding roadways.

Urban crash-related child pedestrian injury incidence and characteristics associated with injury severity

OBJECTIVE

Describe age-based urban pedestrian versus auto crash characteristics and identify crash characteristics associated with injury severity.

MATERIALS AND METHODS

Secondary analysis of the 2004-2010 National Highway and Traffic Safety Administration database for Illinois. All persons in Chicago crashes with age data who were listed as pedestrians (n=7175 child age ≤19 yo, n=16,398 adult age ≥20 yo) were included. Incidence and crash characteristics were analyzed by age groups and year. Main outcome measures were incidence, crash setting, and injury severity. Multivariate logistic regression analysis was performed to estimate injury severity by crash characteristics.

RESULTS

Overall incidence was higher for child (146.6 per 100,000) versus adult (117.3 per 100,000) pedestrians but case fatality rate was lower (0.7% for children, 1.7% for adults). Child but not adult pedestrian injury incidence declined over time (trend test p<0.0001 for <5 yo, 5-9 yo, and 10-14 yo; p<0.05 for 15-19 yo, p=0.96 for ≥20 yo). Most crashes for both children and adults took place during optimal driving conditions. Injuries were more frequent during warmer months for younger age groups compared to older (χ(2)p<0.001). Midblock crashes increased as age decreased (p<0.0001 for trend). Most crashes occurred at sites with sub-optimal traffic controls but varied by age (p<0.0001 for trend). Crashes were more likely to be during daylight on dry roads in clear weather conditions for younger age groups compared to older (χ(2)p<0.001). Daylight was associated with less severe injury (child OR 0.93, 95% CI 0.87-0.98; adult OR 0.90, 95% CI 0.87-0.93).

CONCLUSION

The incidence of urban pedestrian crashes declined over time for child subgroups but not for adults. The setting of pedestrian crashes in Chicago today varies by age but is similar to that seen in other urban locales previously. Injuries for all age groups tend to be less severe during daylight conditions. Age-based prevention efforts may prove beneficial.

The walking environment in Lima, Peru and pedestrian-motor vehicle collisions: an exploratory analysis

OBJECTIVE

Pedestrians comprise 78% of the road fatalities in Peru. The objective of this study was to explore the relationship between the walking environment and pedestrian-motor vehicle collisions.

METHODS

A matched case-control study was used to detect the odds of a pedestrian-motor vehicle collision at a pedestrian crossing location. Data were collected from 11 sampled police commissaries in Lima, Peru.

RESULTS

In a multivariable model adjusting for vehicle and pedestrian flow, pedestrian collisions were less likely in the presence of a curb and sidewalk on both roadway sides (odds ratio [OR] = 0.19, 95% confidence interval [CI], 0.11-0.33) or a pedestrian barricade (OR = 0.11, 95% CI, 0.01-0.81). There was a greater risk of collisions for each street vendor present (OR = 2.82, 95% CI, 1.59-5.00) or whether any parked vehicles (OR = 3.67, 95% CI, 1.18-11.4) were present.

CONCLUSIONS

Improving or addressing these potentially modifiable features of the walking environment could improve pedestrian safety in Lima and in similar urban settings in low- and middle-income countries.

Contribution of the physical environment to socioeconomic gradients in walking in the Whitehall II study

Socioeconomic gradients in walking are well documented but the underlying reasons remain unclear. We examined the contribution of objective measures of the physical environment at residence to socioeconomic gradients in walking in 3363 participants (50-74years) from the Whitehall II study (2002-2004). Individual-level socioeconomic position was measured as most recent employment grade. The contribution of multiple measures of the physical environment to socioeconomic position gradients in self-reported log transformed minutes walking/week was examined by linear regression. Objective measures of the physical environment contributed only to a small extent to socioeconomic gradients in walking in middle-aged and older adults living in Greater London, UK. Of these, only the number of killed and seriously injured road traffic casualties per km of road was predictive of walking. More walking in areas with high rates of road traffic casualties per km of road may signal an effect not of injury risk but of more central locations with multiple destinations within short distances ('compact neighbourhoods'). This has potential implications for urban planning to promote physical activity.

Safely active mobility for urban baby boomers: The role of neighborhood design

Many urban designers and researchers argue that walkable urban environments can encourage older residents' walking activities that benefit their physical health. However, walking also exposes older adults to safety risks, including due to traffic accidents. This study seeks to reveal the interactions between urban form and safety affecting urban baby boomers' walking behavior. Spatial analysis reveals traffic collision patterns in urban Boston neighborhoods, detecting hotspots around activity centers. Structural equation modeling, estimated on individual data collected from a mail-back survey and utilizing numerous measures of neighborhood urban form and accessibility, then attempts to reveal the causal, interacting relationships between neighborhood-level urban form, traffic crashes, and baby boomers' walking behavior. The analysis identifies significant effects of walkable urban forms (e.g., mixed use, well-connected streets, and good access to potential destinations) on older adults' walking. Yet, accessibility to retail, as well as traffic speed and volume, are positively associated with the traffic collision frequency. The results suggest more cautious approaches may be necessary for designing urban spaces for walkability and also call into question prescriptions based on the "safety in numbers" hypothesis.

Socioeconomic status accounts for rapidly increasing geographic variation in the incidence of poor fetal growth

Fetal growth is an important risk factor for infant morbidity and mortality. In turn, socioeconomic status is a key predictor of fetal growth; however, other sociodemographic factors and environmental effects may also be important. This study modelled geographic variation in poor fetal growth after accounting for socioeconomic status, with a fixed effect for socioeconomic status and a combination of spatially-correlated and spatially-uncorrelated random effects. The dataset comprised 88,246 liveborn singletons, aggregated within suburbs in Perth, Western Australia. Low socioeconomic status was strongly associated with an increased risk of poor fetal growth. An increase in geographic variation of poor fetal growth from 1999–2001 (interquartile odds ratio among suburbs = 1.20) to 2004–2006 (interquartile odds ratio = 1.40) indicated a widening risk disparity by socioeconomic status. Low levels of residual spatial patterns strengthen the case for targeting policies and practices in areas of low socioeconomic status for improved outcomes. This study indicates an alarming increase in geographic inequalities in poor fetal growth in Perth which warrants further research into the specific aspects of socioeconomic status that act as risk factors.

Neighborhood social inequalities in road traffic injuries: the influence of traffic volume and road design

OBJECTIVES

We examined the extent to which differential traffic volume and road geometry can explain social inequalities in pedestrian, cyclist, and motor vehicle occupant injuries across wealthy and poor urban areas.

METHODS

We performed a multilevel observational study of all road users injured over 5 years (n=19,568) at intersections (n=17,498) in a large urban area (Island of Montreal, Canada). We considered intersection-level (traffic estimates, major roads, number of legs) and area-level (population density, commuting travel modes, household income) characteristics in multilevel Poisson regressions that nested intersections in 506 census tracts.

RESULTS

There were significantly more injured pedestrians, cyclists, and motor vehicle occupants at intersections in the poorest than in the richest areas. Controlling for traffic volume, intersection geometry, and pedestrian and cyclist volumes greatly attenuated the event rate ratios between intersections in the poorest and richest areas for injured pedestrians (-70%), cyclists (-44%), and motor vehicle occupants (-44%).

CONCLUSIONS

Roadway environment can explain a substantial portion of the excess rate of road traffic injuries in the poorest urban areas.

A review of spatial methods in epidemiology, 2000-2010

Understanding the impact of place on health is a key element of epidemiologic investigation, and numerous tools are being employed for analysis of spatial health-related data. This review documents the huge growth in spatial epidemiology, summarizes the tools that have been employed, and provides in-depth discussion of several methods. Relevant research articles for 2000-2010 from seven epidemiology journals were included if the study utilized a spatial analysis method in primary analysis (n = 207). Results summarized frequency of spatial methods and substantive focus; graphs explored trends over time. The most common spatial methods were distance calculations, spatial aggregation, clustering, spatial smoothing and interpolation, and spatial regression. Proximity measures were predominant and were applied primarily to air quality and climate science and resource access studies. The review concludes by noting emerging areas that are likely to be important to future spatial analysis in public health.

The link between built environment, pedestrian activity and pedestrian-vehicle collision occurrence at signalized intersections

This paper studies the influence of built environment (BE) - including land use types, road network connectivity, transit supply and demographic characteristics - on pedestrian activity and pedestrian-vehicle collision occurrence. For this purpose, a two-equation modeling framework is proposed to investigate the effect of built environment on both pedestrian activity and vehicle-pedestrian collision frequency at signalized intersections. Using accident data of ambulance services in the City of Montreal, the applicability of our framework is illustrated. Different model settings were attempted as part of a model sensitivity analysis. Among other results, it was found that the BE in the proximity of an intersection has a powerful association with pedestrian activity but a small direct effect on pedestrian-vehicle collision frequency. This suggests that the impact of BE is mainly mediated through pedestrian activity. In other words, strategies that encourage densification, mix of land uses and increase in transit supply will increase pedestrian activity and may indirectly, with no supplementary safety strategies, increase the total number of injured pedestrians. In accordance with previous research, the number of motor vehicles entering a particular intersection is the main determinant of collision frequency. Our results show that a 30% reduction in the traffic volume would reduce the total number of injured pedestrians by 35% and the average risk of pedestrian collision by 50% at the intersections under analysis. Major arterials are found to have a double negative effect on pedestrian safety. They are positively linked to traffic but negatively associated with pedestrian activity. The proposed framework is useful for the identification of effective pedestrian safety actions, the prediction of pedestrian volumes and the appropriate safety design of new urban developments that encourage walking.

Protecting vulnerable road users from injury

Aymery Constant and Emmanuel Lagarde discuss policies to protect pedestrians, and pedal and motor cyclists, from injury.