Assessing the predictability of surrogate safety measures as crash precursors based on vehicle trajectory data prior to crashes.

This study aims to investigate the predictability of surrogate safety measures (SSMs) for real-time crash risk prediction. We conducted a year-long drone video collection on a busy freeway in Nanjing, China, and collected 20 rear-end crashes. The predictability of SSMs was defined as the probability of crash occurrence when using SSMs as precursors to crashes. Ridge regression models were established to explore contributing factors to the predictability of SSMs. Four commonly used SSMs were tested in this study. It was found that modified time-to-collision (MTTC) outperformed other SSMs when the early warning capability was set at a minimum of 1 s. We further investigated the cost and benefit of SSMs in safety interventions by evaluating the number of necessary predictions for successful crash prediction and the proportion of crashes that can be predicted accurately. The result demonstrated these SSMs were most efficient in proactive safety management systems with an early warning capability of 1 s. In this case, 308, 131, 281, and 327,661 predictions needed to be made before a crash could be successfully predicted by TTC, MTTC, DRAC, and PICUD, respectively, achieving 75 %, 85 %, 35 %, and 100 % successful crash identifications. The ridge regression results indicated that the predefined threshold had the greatest impact on the predictability of all tested SSMs.

Learner experiences of safety at public high schools in three South African townships: Baseline findings from the National School Safety Framework learner surveys.

Background: Despite progressive policies and frameworks on school safety by the Department of Basic Education, safety remains a concern in South African schools. Methods: A cross-sectional descriptive design was employed using the National School Safety Framework (NSSF) 152-question learner survey, exploring perceptions and experiences pertaining to eight safety domains: dangerous objects, drugs and alcohol, bullying, verbal abuse, physical violence, discrimination, sexual violence, and journey to and from school. Grade 9-11 learners from 15 government-funded high schools in the Girls Achieve Power trial in Khayelitsha, Soweto, and Thembisa townships were surveyed (March 2018 - April 2019), sampling 10% of the school population. Data analysis included Principal Component Analysis (PCA), reducing correlated variables into fewer questions, then analysis on a scree plot by calculating eigenvalues; repeated PCA with those that had a minimum eigenvalue of 1 and Cronbach Alpha test for internal reliability. Eleven composite variables were included in the final analysis. Results: In total, 1034 learners completed the NSSF learner survey; 52.9% were female and the mean age was 16 years (SD=1.36). Results show statistically significant associations between four of the 11 composite variables in relation to sex. Over half (55%) of males have experienced peer provocation and relational aggression (p<0.001). Fifty-eight percent of females reported feeling unsafe on their way to and from school (p<0.003). Over half of males reported that their school was not effective in enforcing discipline (p=0.002) while 58% of females noted they could comfortably report any form of experienced or witnessed violence at school, to their educators (p<0.000). Conclusions: Violence continues to be a concern in South African schools. Interventions should work across the ecological model to effectively prevent and reduce violence at school and community levels. Strengthened NSSF implementation is critical to achieving this. We recommend NSSF learner survey adaptations to increase utility and implementation.

Firearm Practices, Perceptions of Safety, and Opinions on Injury Prevention Strategies Among California Adults.

Importance: Safe firearm storage and other interventions may reduce pediatric firearm deaths and injuries. Objective: To compare firearm ownership and storage practices, opinions on firearm injury prevention strategies, and perceptions of safety among adults in California households with and without children and/or adolescents. Design, Setting, and Participants: This survey study used data from the 2018 California Safety and Well-being Survey, a California-representative, probability-based internet survey. Respondents were part of the Ipsos KnowledgePanel, an online research panel that uses address-based sampling and provides survey weights to produce estimates representative of the adult population of California. Main Outcomes and Measures: Topics included firearm storage practices, opinions on interventions to reduce pediatric firearm injury, and perceptions of household safety related to firearm ownership. Respondents were stratified by firearm ownership and household presence or absence of children and/or adolescents. Weighted percentages and 95% CIs are presented. Results: Of 5232 invited panel members, 2558 (48.9%) completed the survey. Among respondents, 52.5% (95% CI, 49.3%-55.7%) were women, 42.9% (95% CI, 39.9%-45.9%) were White, 30.0% (95% CI, 26.8%-32.9%) lived in homes with children, and the mean (SD) age was 48.0 (17.1) years. Among those in homes with children, more than two-thirds of individuals who owned firearms (70.6% [95% CI, 50.1%-85.2%]) and more than half of individuals who did not own firearms but lived in homes with guns (54.9% [95% CI, 37.9%-70.8%]) reported that they believed a firearm in the home made it safer. Half of those who owned firearms (52.3% [95% CI, 34.9%-69.2%]) and more than three-quarters of individuals who did not own firearms but lived in homes with guns (78.4% [95% CI, 57.5%-90.7%]) reported it was always appropriate for parents to inquire about unlocked guns in homes where their children play. Among those who had previously owned at least 1 gun but no longer did, 13.3% (95% CI, 7.1%-23.8%) reported getting rid of guns at least in part due to concern for the safety of a child in the home. Nearly two-thirds of those who owned firearms living with children and/or adolescents (64.5% [95% CI, 46.5%-79.2%]) did not store all firearms in the most secure manner (ie, unloaded and locked up), compared with 36.4% (95% CI, 29.4%-44.1%) of individuals who owned firearms but did not live with children. Conclusions and Relevance: In this study, although a substantial percentage of individuals who owned guns and lived with children did not store all firearms as recommended, parents and caregivers who owned firearms reported being amenable to interventions that reduce young people's risk of firearm-related harm. Future work should investigate acceptable risk reduction and safe storage interventions.

Firearm Storage Practices of US Members of the American College of Surgeons.

BACKGROUND: As a part of its firearm injury prevention action plan, the American College of Surgeons (ACS) surveyed the entire US ACS membership regarding individual members' knowledge, experience, attitudes, degree of support for ACS Committee on Trauma (COT) firearm programs, and degree of support for a range of firearm injury prevention policies. This survey included questions regarding members' prevalence of firearm ownership, type of firearm(s) owned, type of firearm(s) in the home, personal reasons for firearm ownership, and methods of firearm/ammunition storage. STUDY DESIGN: An email invitation to participate in an anonymous, 23-item survey on firearms was sent to all US ACS members (n = 54,761) by a contracted survey research firm. Cross tabulation of questionnaire items by demographic characteristics and chi-square analyses were performed with statistical significance p < 0.05. RESULTS: The overall response rate was 20.4% (11,147/54,761). Forty-two percent of respondents keep firearms in their home (82% long guns, 82% handguns; 32% high-capacity magazine fed, semi-automatic rifles); 75% keep guns for self-defense/protection, 73% for target shooting; 39% store firearms unlocked, and 32% store guns unlocked and loaded. Results vary by practice/training location, practice type, military experience, sex, age, presence of children in the home, level of training, and race/ethnicity. CONCLUSIONS: A significant percentage of ACS members keep firearms in their home, and nearly one-third store firearms in an unlocked and loaded fashion. Safe storage is a basic tenet of responsible firearm ownership. These data present opportunities for engaging surgeons in efforts to improve safe firearm storage.

Improving the safety of distracted pedestrians with in-ground flashing lights. A railway crossing field study.

INTRODUCTION: Current signage at intersections is designed for attentive pedestrians who are looking ahead. Such signage may not be sufficient when distracted by smartphones. Illuminated in-ground LED lights at crossings are an innovative solution to alert distracted pedestrians. METHOD: We conducted a field study at a railway crossing equipped with in-ground lights to assess whether distracted pedestrians (N = 34, Mean age 33.6 ±â€¯8.6 years) could detect these lights and how this impacted on their visual scanning and crossing behaviour. This involved a 2 × 3 repeated measures design exploring the impact of the presence (treatment) or absence (control) of in-ground lights (treatment) at a crossing, and a distractor task presented through a mobile device (none, visual, and audio) on eye movements recorded using an eye tracker, and verbal reporting of when participants detected the lights. RESULTS: Participants engaged in the distraction tasks as evidenced by their accuracy and reaction times in all conditions. With both the audio and visual distraction tasks, participants looked at the in-ground LEDs and detected their activation as accurately as when not distracted (95%). While most participants detected the lights at their activation, visual distraction resulted in 10% of the detections occurring as participants entered the rail corridor, suggesting effectiveness in gaining pedestrians' attention. Further, participants were significantly less likely to check for trains when visually distracted (70%), a 10% reduction compared to the no or audio distractor conditions (80% and 78% respectively). The introduction of the in-ground lights resulted in appropriate scanning of the rail tracks (77% and 78% for the visual and auditory distractor tasks respectively) similar to that of non-distracted participants for the crossing without lights (80%). CONCLUSIONS: Our findings indicate that illuminated in-ground lights could be useful in attracting the attention of distracted pedestrians at railway level crossings, and possibly at other road intersections. Practical Applications: Illuminated in-ground lights can be installed at rail and road intersections with known pedestrian distraction as a countermeasure. Further research is necessary to understand their long-term effects.

Patient Characteristics and Perspectives of Firearm Safety Discussions in the Emergency Department.

INTRODUCTION: Firearm injury prevention discussions with emergency department (ED) patients provide a unique opportunity to prevent death and injury in high-risk patient groups. Building mutual understanding of safe firearm practices between patients and providers will aid the development of effective interventions. Examining ED patient baseline characteristics, perspectives on healthcare-based safety discussions, and experience with and access to firearms, will allow practitioners to craft more effective messaging and interventions. METHODS: Using an institutional review board-approved cross-sectional survey modified from a validated national instrument, we recruited 625 patients from three large, urban, academically affiliated EDs in the South to assess patient baseline characteristics, perspectives regarding firearms and firearm safety discussions, and prior violence history, as well as firearm access and safety habits. We compared the degree to which patients were open to discussions regarding firearms across a variety of provider types and clinical scenarios between those with and without gun access. RESULTS: Of the 625 patients consented and eligible for the study, 306 had access to firearms. The patients with firearm access were predominantly male, were more likely to have military experience, live in an urban or suburban region, and have experienced prior violence when compared to those without firearm access. Patients with and without gun access view firearm safety discussions with their healthcare provider as acceptable and analogous to other behavioral health interventions (i.e., helmet/seat belt use, alcohol/cigarette use). Patients were also accepting of these firearm safety discussions in many clinical contexts and led by multiple provider types. Of the patients with gun access, storage of each type of firearm was reviewed and the primary reason for ownership was for personal protection across all firearm types. CONCLUSION: Patients in the ED indicate openness to firearm safety discussions delivered by a variety of providers and in diverse clinical scenarios. Healthcare providers engaging firearm owners in appropriate risk-benefit discussions using a trauma-informed approach is a critical next step in research and intervention.

Neighborhood environmental attributes and walking mobility decline: A longitudinal ecological study of mid-to-older aged Australian adults.

OBJECTIVES: Cross-sectional studies have found some built environmental attributes to be associated with residents' lower levels of mobility (functional capacity to walk outside the home). However, less is known about what environmental attributes are related to mobility decline. This longitudinal study examined area-level associations of specific environmental attributes with mid-to-older aged adults' changes in walking mobility. METHODS: Data collected from 4,088 adults (aged 46-71 years at baseline) who participated in a cohort study in Brisbane, Australia were used. The outcome was the change in self-reported mobility score (SF-36) from 2013 to 2016, which were aggregated at the neighborhood (N = 156) and suburb (N = 99) levels, due to the known lack of sensitivity in SF-36 subscales to individual changes. Linear regression analysis examined associations of mobility change with seven environmental attributes measured at baseline (residential density, intersection density, land use mix, density of walking/bike paths, park density, bus stop density, density of social incivilities), adjusting for confounding variables. RESULTS: Participants on average reported 4% of mobility decline during the 3-year study period. It was found that greater land use diversity was consistently associated with less decline in walking mobility, while greater density of social incivilities was associated with more decline in walking mobility. The latter finding was significant only at the neighborhood level. No consistent associations were observed for residential density, intersection density, density of walking/bike paths, park density, and bus stop density. DISCUSSION: Our findings suggest that mid-to-older aged adults who live in areas with lower land use diversity and more social incivilities may be at risk of developing mobility limitations. Recommended policies to slow residents' mobility decline and to achieve aging in place include improving these environmental attributes where needed and advising older adults to relocate to safer, mixed-use neighborhoods.

Evaluation of rapid drug safety communication materials for patients in Japan.

Since 2011, pharmaceutical companies in Japan have been required to issue two types of documents regarding severe adverse drug reactions reported post-marketing, namely the Rapid Safety Communication Materials for Patients and the Related Materials. However, the adequacy of these documents has not yet been systematically assessed. The aim of this study was to evaluate the adequacy of these two types of materials. The Rapid Safety Communications for Patients were obtained from the Pharmaceuticals and Medical Devices Agency (PMDA) website. The Related Materials were obtained from pharmaceutical companies or the PMDA website. Three assessors independently scored the Rapid Safety Communication for Patients and the Related Materials using the Centers for Disease Control and Prevention Clear Communication Index (CCI). In addition, the contents and descriptions of the materials were analyzed. In total, 13 materials for seven drugs were assessed. Almost all materials contained the "main message" and "call to action". However, the average CCI scores for the Rapid Safety Communication for Patients and Related Materials for Patients were 68.8 and 74.3 (out of 100), respectively. Further, none of the evaluated materials were scored above the CCI threshold score (i.e., ≥ 90%). Descriptions regarding "language", "state of science", and "risk" were not adequate. In particular, the terminology used in materials seemed difficult for patients to understand. In conclusion, the Japanese Rapid Communication Materials for Patients require improvement. Furthermore, a system for evaluating these materials prior to publication should be established.

Vaccine side-effects and SARS-CoV-2 infection after vaccination in users of the COVID Symptom Study app in the UK: a prospective observational study.

BACKGROUND: The Pfizer-BioNTech (BNT162b2) and the Oxford-AstraZeneca (ChAdOx1 nCoV-19) COVID-19 vaccines have shown excellent safety and efficacy in phase 3 trials. We aimed to investigate the safety and effectiveness of these vaccines in a UK community setting. METHODS: In this prospective observational study, we examined the proportion and probability of self-reported systemic and local side-effects within 8 days of vaccination in individuals using the COVID Symptom Study app who received one or two doses of the BNT162b2 vaccine or one dose of the ChAdOx1 nCoV-19 vaccine. We also compared infection rates in a subset of vaccinated individuals subsequently tested for SARS-CoV-2 with PCR or lateral flow tests with infection rates in unvaccinated controls. All analyses were adjusted by age (≤55 years vs >55 years), sex, health-care worker status (binary variable), obesity (BMI <30 kg/m2vs ≥30 kg/m2), and comorbidities (binary variable, with or without comorbidities). FINDINGS: Between Dec 8, and March 10, 2021, 627 383 individuals reported being vaccinated with 655 590 doses: 282 103 received one dose of BNT162b2, of whom 28 207 received a second dose, and 345 280 received one dose of ChAdOx1 nCoV-19. Systemic side-effects were reported by 13·5% (38 155 of 282 103) of individuals after the first dose of BNT162b2, by 22·0% (6216 of 28 207) after the second dose of BNT162b2, and by 33·7% (116 473 of 345 280) after the first dose of ChAdOx1 nCoV-19. Local side-effects were reported by 71·9% (150 023 of 208 767) of individuals after the first dose of BNT162b2, by 68·5% (9025 of 13 179) after the second dose of BNT162b2, and by 58·7% (104 282 of 177 655) after the first dose of ChAdOx1 nCoV-19. Systemic side-effects were more common (1·6 times after the first dose of ChAdOx1 nCoV-19 and 2·9 times after the first dose of BNT162b2) among individuals with previous SARS-CoV-2 infection than among those without known past infection. Local effects were similarly higher in individuals previously infected than in those without known past infection (1·4 times after the first dose of ChAdOx1 nCoV-19 and 1·2 times after the first dose of BNT162b2). 3106 of 103 622 vaccinated individuals and 50 340 of 464 356 unvaccinated controls tested positive for SARS-CoV-2 infection. Significant reductions in infection risk were seen starting at 12 days after the first dose, reaching 60% (95% CI 49-68) for ChAdOx1 nCoV-19 and 69% (66-72) for BNT162b2 at 21-44 days and 72% (63-79) for BNT162b2 after 45-59 days. INTERPRETATION: Systemic and local side-effects after BNT162b2 and ChAdOx1 nCoV-19 vaccination occur at frequencies lower than reported in phase 3 trials. Both vaccines decrease the risk of SARS-CoV-2 infection after 12 days. FUNDING: ZOE Global, National Institute for Health Research, Chronic Disease Research Foundation, National Institutes of Health, UK Medical Research Council, Wellcome Trust, UK Research and Innovation, American Gastroenterological Association.

An overview of tram tracks related cycling injuries in Ghent, Belgium.

OBJECTIVE: There is a paucity of data on the incidence and severity of tram tracks related cycling injuries. The aim of this study is to get insight into the incidence, severity and characteristics of tram tracks related cycling injuries, potentially defining significant 'hotspots' in the Ghent city area. METHODS: A one-year, multicenter, prospective, observational study was conducted. Patients presenting to the emergency departments of all 4 Ghent hospitals with tram tracks related cycling injury, were included. Data on patient demographics, circumstances of the accident and type of injury were collected. RESULTS: 149 patients were included, with a median age of 31 years. 42 patients had fractures, 39 patients required wound sutures, 79 and 49 patients suffered from bruising and abrasions respectively. Only 5 patients required admission. No patients died or suffered life-threatening injuries. Women (65.1%) presented more frequently than men (34.9%). Forty-tree percent of all accidents happened in autumn (p < 0.001). Accidents happened more frequently in rainy conditions (p < 0.001). Mean number of days off work was 2.7 days, significantly increasing to 6.56 days when sustaining a fracture or dislocation (p = 0.02). CONCLUSION: Tram tracks are potentially dangerous and may lead to clinically important injuries and significant number of days off work.

Composite performance indicators for helmet and seat-belt enforcement as imprecise data.

OBJECTIVES: Composite road safety performance indicators (RSPIs) are useful tools in regional road safety planning. Among the indicators and data calculated by the World Health Organization (WHO), information on the effectiveness of law enforcement on various risk factors for road casualties were provided, which can be considered as qualitative indicators. The purpose of this study is to analyze the performance indicators related to the percentage of helmet and seat-belt use versus the qualitative enforcement scores attributed by WHO. METHODS: This analysis was performed for 30 member states of WHO and will show how and with what degree of efficiency the qualitative output of the enforcement score acts versus the input percentage of seat-belt and helmet use. The qualitative nature of the output index has led us to depart the traditional analysis of crisp numerical indicators related to road safety performance and to consider data as imprecise or fuzzy indices. In this study we used two methods including imprecise DEA-based CIs and fuzzy DEA-based CIs, respectively. RESULTS: Results show that the clear score achieved by the Imprecise DEA-based CI model is easy to interpret and use. Whereas, in the Fuzzy DEA-based CI model, the fuzzy indicator scores obtained based on the level of several probabilities are strong in capturing the uncertainties related to human behavior. CONCLUSIONS: Both RSPIs are applicable with slight differences that were in the order of countries and the ease of reading the results. We also found that each method has different strengths and that the FDEA-based CIs method is more accurate and more in line with the inputs than the IDEA-based CIs method.

The effect of human mobility and control measures on traffic safety during COVID-19 pandemic.

As mobile device location data become increasingly available, new analyses are revealing the significant changes of mobility pattern when an unplanned event happened. With different control policies from local and state government, the COVID-19 outbreak has dramatically changed mobility behavior in affected cities. This study has been investigating the impact of COVID-19 on the number of people involved in crashes accounting for the intensity of different control measures using Negative Binomial (NB) method. Based on a comprehensive dataset of people involved in crashes aggregated in New York City during January 1, 2020 to May 24, 2020, people involved in crashes with respect to travel behavior, traffic characteristics and socio-demographic characteristics are found. The results show that the average person miles traveled on the main traffic mode per person per day, percentage of work trip have positive effect on person involved in crashes. On the contrary, unemployment rate and inflation rate have negative effects on person involved in crashes. Interestingly, different level of control policies during COVID-19 outbreak are closely associated with safety awareness, driving and travel behavior, and thus has an indirect influence on the frequency of crashes. Comparing to other three control policies including emergence declare, limits on mass gatherings, and ban on all nonessential gathering, the negative relationship between stay-at-home policy implemented in New York City from March 20, 2020 and the number of people involved crashes is found in our study.

Injury crashes and the relationship with disease causing excessive daytime sleepiness.

OBJECTIVE: The objective of this study was to understand the relationship between some of the most common diseases that are known to contribute to excessive daytime sleepiness (EDS) and traffic injury crashes. Specific focus was on the relationship between disease and crash type (single-vehicle or multiple-vehicle crash) and between disease and injury severity. METHODS: This registry-based study considered all passenger car drivers involved in a crash in Sweden between 2011 and 2016 who were 40 years or older at the time of the crash (n = 54,090). For each crash-involved driver, selected medical diagnoses registered from 1997 until the day before the crash were extracted from the National Patient Register. The drivers were assigned to 1 of 4 groups, depending on prior diseases: sleep apnea (SA; group 1, n = 2,165), sleep disorders (group 2, n = 724), Parkinson's or epilepsy (group 3, n = 645) and a reference group (group 4, n = 50,556). Logistic regression analysis compared single-vehicle crashes with multiple-vehicle crashes and moderately/severely injured drivers with slightly/uninjured drivers. RESULTS: Drivers with EDS-related diseases (groups 1-3) had higher probability of a single-vehicle crash than a multiple-vehicle crash compared to the reference group. The most sizeable effect was found for Parkinson's/epilepsy with an odds ratio (OR) of 2.5 (confidence interval [CI], 2.1-3.0). For multiple-vehicle crashes, the probability of a moderate/severe injury was higher for drivers with other sleep disorders (OR = 1.5; CI, 1.0-2.2) and Parkinson's/epilepsy (OR = 1.6; CI, 1.1-2.3) compared to the reference group. CONCLUSIONS: This study has made first steps toward understanding the relationship between some of the most common diseases that are known to contribute to EDS and crashes. Having Parkinson's/epilepsy, in particular, elevated the probability of a single-vehicle crash compared to a multiple-vehicle crash. A single-vehicle crash was seen as indicative of causing a crash; thus, having Parkinson's/epilepsy could be interpreted as a risk factor for crash involvement. Having Parkinson's/epilepsy, as well as other sleep disorders, was also related to more severe outcomes in multiple-vehicle crashes, given that a crash occurred. This was not identified in single-vehicle crashes.

Studying freeway merging conflicts using virtual reality technology.

INTRODUCTION: This research aims to investigate the perceptions and reactions of drivers regarding freeway merging situation, utilizing a new approach with the basis of a multilevel simulation platform which incorporates virtual reality (VR) technology. METHODS: A VR driving environment integrated with traffic micro-simulation was developed to evaluate driving behaviors and the impact of merging decisions in terms of traffic conflicts. The driving experiments were conducted under a variety of circumstances, including varying traffic flows and the presence of ramp metering. The Surrogate Safety Assessment Model (SSAM) was utilized to extract the number of conflicts from the micro-simulation results. RESULTS: The final results indicated that the probability of conflict has a positive correlation with traffic flow, while conflict frequency at freeway merges is affected by the presence of ramp metering due to its potentiality to enhance driver decisions and reduce the drivers' pressure when they make maneuvers. Practical Applications: The findings reveal that the proposed VR simulation platform is a useful tool to improve the safety of freeway merging. It has the potential to enhance driver skills and can also be used in the study of human-machine interaction.

Assessment of temporal stability in risk factors of crashes at horizontal curves on rural two-lane undivided highways.

INTRODUCTION: Safety of horizontal curves on rural two-lane, two-way undivided roadways is not fully explored. This study investigates factors that impact injury severity of such crashes. METHOD: To achieve the aim of this paper, issues associated with police-reported crash data such as unobserved heterogeneity and temporal stability need to be accounted for. Hence, a mixed logit model was estimated, while heterogeneity in means and variances is investigated by considering four injury severity outcomes for drivers: severe injury, moderate injury, possible injury, and no injury. Crash data for the period between 2011 and 2016 for crashes that occurred in the state of Oregon was analyzed. Temporal stability in factors determining the injury severity was investigated by identifying three time periods through splitting crash data into 2011-2012, 2013-2014, and 2015-2016. RESULTS: Despite some factors affecting injuries in all specified time periods, the values of the marginal effects showed relative differences. The estimation results revealed that some factors increased the risk of being involved in severe injury crashes, including head-on collisions, drunk drivers, failure to negotiate curves, older drivers, and exceeding the speed limits. CONCLUSIONS: The hypothesis that attributes of injury severity are temporally stable is rejected. For example, young drivers (30 years old and younger) and middle-aged drivers were found to be temporally instable over time. Practical applications: The findings could help transportation authorities and safety professionals to enhance the safety of horizontal curves through appropriate and effective countermeasures.

Driver glare exposure with different vehicle frontlighting systems.

INTRODUCTION: Highway safety performance at night has received less attention in research than daytime, despite the higher accident rates occurring under night-time conditions. This study presents a procedure to assess the potential hazard for drivers created by headlight glare and its interaction with the geometric design of highways. METHOD: The proposed procedure consists of a line-of-sight analysis performed by a geoprocessing model in geographic information systems to determine whether the rays of light that connect headlights and oncoming drivers are obstructed by either the roadway or its roadsides. Then, the procedure checks whether the non-obstructed rays of light are enclosed by a given headlight beam. Different hypotheses were set concerning the headlight beam features, including the horizontal spread angle and whether the headlights are fixed or swiveling. A highway section was selected to test and validate the procedure proposed. A 3D recreation of the highway and its environment derived from a LiDAR point cloud was used for this purpose. RESULTS: The findings disclose how glare is produced on tangents, horizontal curves, transitions between them and sequences of curves. The effect of visual obstructions conveniently placed is also discussed. CONCLUSIONS: A greater glare incidence is produced as the horizontal headlights spread angle increases. Swiveling headlights increase glare on highways left curves and reduce it on right curves. Practical Applications: The procedure and conclusions of this study can contribute to develop more effective glare avoidance technologies as well as identify and assess glare-prone sections. The glare evaluation assists in evaluating glare countermeasures such as deciding whether to place a vegetation barrier and where.

A data mining approach to deriving safety policy implications for taxi drivers.

INTRODUCTION: Traffic safety issues associated with taxis are important because the frequency of taxi crashes is significantly higher than that of other vehicle types. The purpose of this study is to derive safety implications to be used for developing policies to enhance taxi safety based on analyzing intrinsic characteristics underlying the cause of traffic accidents. METHOD: An in-depth questionnaire survey was conducted to collect a set of useful data representing the intrinsic characteristics. A total of 781 corporate taxi drivers participated in the survey in Korea. The proposed analysis methodology consists of two-stage data mining techniques, including a random forest method, with data that represents the working condition and welfare environment of taxi drivers. In the first stage, the drivers' intrinsic characteristics were derived to classify four types of taxi drivers: unspecified normal, work-life balanced, overstressed, and work-oriented. Next, priority was determined for classifying high-risk taxi drivers based on factors derived from the first analysis. RESULTS: The derived policies can be categorized into three groups: 'the development of new policies,' 'the improvement of existing policies,' and 'the elimination of negative factors.' Establishing a driving capability evaluation system for elderly drivers, developing mental health management programs for taxi drivers, and inspecting the taxi's internal conditions were proposed as new policies. Improving the driver's wage system, supporting the improvement of rest facilities, and supporting the installation of security devices for protecting taxi drivers are methods for improving existing policies to reinforce the traffic safety of taxi drivers. Last, restricting overtime work for taxi drivers was proposed as a policy to eliminate negative factors for improving taxi traffic safety. Practical Applications: It is expected that by devising effective policies using the policy implications suggested in this study, taxi traffic accidents can be prevented and the quality of life of taxi drivers can be improved.

Investigating hazardous factors affecting freeway crash injury severity incorporating real-time weather data: Using a Bayesian multinomial logit model with conditional autoregressive priors.

INTRODUCTION: It has been demonstrated that weather conditions have significant impacts on freeway safety. However, when employing an econometric model to examine freeway crash injury severity, most of the existing studies tend to categorize several different adverse weather conditions such as rainy, snowy, and windy conditions into one category, "adverse weather," which might lead to a large amount of information loss and estimation bias. Hence, to overcome this issue, real-time weather data, the value of meteorological elements when crashes occurred, are incorporated into the dataset for freeway crash injury analysis in this study. METHODS: Due to the possible existence of spatial correlations in freeway crash injury data, this study presents a new method, the spatial multinomial logit (SMNL) model, to consider the spatial effects in the framework of the multinomial logit (MNL) model. In the SMNL model, the Gaussian conditional autoregressive (CAR) prior is adopted to capture the spatial correlation. In this study, the model results of the SMNL model are compared with the model results of the traditional multinomial logit (MNL) model. In addition, Bayesian inference is adopted to estimate the parameters of these two models. RESULT: The result of the SMNL model shows the significance of the spatial terms, which demonstrates the existence of spatial correlation. In addition, the SMNL model has a better model fitting ability than the MNL model. Through the parameter estimate results, risk factors such as vertical grade, visibility, emergency medical services (EMS) response time, and vehicle type have significant effects on freeway injury severity. Practical Application: According to the results, corresponding countermeasures for freeway roadway design, traffic management, and vehicle design are proposed to improve freeway safety. For example, steep slopes should be avoided if possible, and in-lane rumble strips should be recommended for steep down-slope segments. Besides, traffic volume proportion of large vehicles should be limited when the wind speed exceeds a certain grade.