A spatial-state-based omni-directional collision warning system for intelligent vehicles

Collision warning systems (CWSs) have been recognized as effective tools in preventing vehicle collisions. Existing systems mainly provide safety warnings based on single-directional approaches, such as rear-end, lateral, and forward collision warnings. Such systems cannot provide omni-directorial enhancements on driver’s perception. Meanwhile, due to the unclear and overlapped activation areas of above single-directional CWSs, multiple kinds of warnings may be triggered mistakenly for a collision. The multi-triggering may confuse drivers about the position of dangerous targets. To this end, this paper develops a spatial-state-based omni-directional collision warning system (S-OCWS), aiming to help drivers identify the specific danger by providing the unique warning. First, the operational domains of rear-end, lateral, and forward collisions are theoretically distinguished. This distinction is attained by a geometric approach with a rigorous mathematical derivation, based on the spatial states and the relative motion states of itself and the target vehicle in real time. Then, a theoretical omni-directional collision warning model is established using time-to-collision (TTC) to clarify activation conditions for different collision warnings. Finally, the effectiveness of the S-OCWS is validated in field tests. Results indicate that the S-OCWS can help drivers quickly and properly respond to the warnings without compromising their control over lateral offsets. In particular, the probability of drivers giving proper responses to FCW doubles when the S-OCWS is on, compared to when the system is off. In addition, the S-OCWS shortens the responses time of nonprofessional drivers, and therefore enhances their safety in driving

Fine-Scale Mapping of the 4q24 Locus Identifies Two Independent Loci Associated with Breast Cancer Risk

Background: A recent association study identified a common variant (rs9790517) at 4q24 to be associated with breast cancer risk. Independent association signals and potential functional variants in this locus have not been explored. Methods: We conducted a fine-mapping analysis in 55,540 breast cancer cases and 51,168 controls from the Breast Cancer Association Consortium. Results: Conditional analyses identified two independent association signals among women of European ancestry, represented by rs9790517 [conditional P = 2.51 × 10−4; OR, 1.04; 95% confidence interval (CI), 1.02–1.07] and rs77928427 (P = 1.86 × 10−4; OR, 1.04; 95% CI, 1.02–1.07). Functional annotation using data from the Encyclopedia of DNA Elements (ENCODE) project revealed two putative functional variants, rs62331150 and rs73838678 in linkage disequilibrium (LD) with rs9790517 (r2 ≥ 0.90) residing in the active promoter or enhancer, respectively, of the nearest gene, TET2. Both variants are located in DNase I hypersensitivity and transcription factor–binding sites. Using data from both The Cancer Genome Atlas (TCGA) and Molecular Taxonomy of Breast Cancer International Consortium (METABRIC), we showed that rs62331150 was associated with level of expression of TET2 in breast normal and tumor tissue. Conclusion: Our study identified two independent association signals at 4q24 in relation to breast cancer risk and suggested that observed association in this locus may be mediated through the regulation of TET2. Impact: Fine-mapping study with large sample size warranted for identification of independent loci for breast cancer risk

Access to urban transportation system for individuals with disabilities

Urbanization and aging population has become a significant issue in many global cities. It is necessary that the design of built environment to be supportive and provide adequate access to essential urban and social resources, e.g. employment, education, medical, social welfare and recreation etc., for all, including individuals with disabilities. Safe, efficient and accessible transportation is a key component of community integration. This study attempts to review the current practices and guidelines for accessible design of transportation, both access to and within transport facilities, based on the information from the United States, United Kingdom, and Hong Kong. Besides, the effects of accessible design of transportation on perceived level of service, accessibility, safety and travel behavior would be examined. Therefore, good practices of accessible design that could address the needs for all, especially the elderly and individuals with different types of disability including visual impairment, hearing difficulty and reduced mobility, could be recommended. Hence, quality of life of vulnerable group can be enhanced, and community integration will be achieved in the long run

Waiting for signalized crossing or walking to footbridge/underpass? Examining the effect of weather using stated choice experiment with panel mixed random regret minimization approach

It is a challenging task for pedestrians to cross a road with multiple traffic lanes and busy traffic. Many footbridges and underpasses have been built in the urban area of metropolitan cities such as Hong Kong to resolve the problem of vehicle-pedestrian conflict. To maximize the utilization and benefit of the installation of such crossing facilities, it is crucial to understand the choice behaviour of pedestrians. Although many studies have examined pedestrian walking behaviour and preference towards crossing facilities, the influence of ratio of perceived values between waiting and walking time on the choice of crossing is not explored. In addition, individual perception and choice may vary with the environmental conditions, which has not been fully accounted for in existing studies. Exposure to extremely hot weather, crowded walkways, and roadside traffic emissions are not favoured. In this study, a stated choice experiment is developed to examine the relationship between possible influencing factors and the crossing choices of pedestrians in Hong Kong. In addition, a regret-based panel mixed multinomial logit approach is adopted to model the choice, accounting for the effects of unobserved heterogeneity and panel data. The results indicate that the choice decision of pedestrians is more sensitive to an increase in waiting time at signalized crossings than to an increase in walking time to access footbridges and underpasses. These findings shed light on future urban and transport planning strategies to improve the walking environment and promote walkability

Effect of Diverging Diamond Interchange (DDI) on safety performance : application of Empirical Bayes method

Urban population and travel demand have been increasing rapidly. It presents a challenge to transport planners and engineers for alleviating traffic congestion and reducing accident risk. Diverging Diamond Interchange (DDI) is an innovative interchange design, which was first introduced in the United States in 2009, aiming to improve the operation and safety performances of freeway interchanges. DDI can accommodate high and unbalanced traffic volume on the arterial, by reducing the number of traffic signal phases and allowing unobstructed left turns for all traffic directions. DDI has been recognized as a cost-effective solution to congested freeway interchanges. However, few studies have investigated the safety effects of DDI. This paper aims to evaluate the change in crash risk of freeway interchanges after the introduction of DDI, using Empirical Bayes (EB) before and after comparison approach. In this study, the crash data of selected DDIs and traditional diamond interchanges (comparison group) in Utah was collected. The safety performance functions (SPF) were calibrated using the negative binomial model, based on the crash data of 26 comparison sites. Then, the crash modification factors for fatal and injury crash, property damage only (PDO) crash, and overall crash were estimated respectively. Moreover, effects of DDI on pedestrian and bicycle safety were also examined. Results indicated that there were significant crash reductions, regardless of crash severity level, at most of the DDIs under investigation, at the 5% level. For instances, reduction in fatal and injury crash was more remarkable

Distractions by work-related activities: The impact of ride-hailing app and radio system on male taxi drivers

Use of ride-hailing mobile apps has surged and reshaped the taxi industry. These apps allow real-time taxi-customer matching of taxi dispatch system. However, there are also increasing concerns for driver distractions as a result of these ride-hailing systems. This study aims to investigate the effects of distractions by different ride-hailing systems on the driving performance of taxi drivers using the driving simulator experiment. In this investigation, fifty-one male taxi drivers were recruited. During the experiment, the road environment (urban street versus motorway), driving task (free-flow driving versus car-following), and distraction type (no distraction, auditory distraction by radio system, and visual-manual distraction by mobile app) were varied. Repeated measures ANOVA and random parameter generalized linear models were adopted to evaluate the distracted driving performance accounting for correlations among different observations of a same driver. Results indicate that distraction by mobile app impairs driving performance to a larger extent than traditional radio systems, in terms of the lateral control in the free-flow motorway condition and the speed control in the free-flow urban condition. In addition, for car-following task on urban street, compensatory behaviour (speed reduction) is more prevalent when distracted by mobile app while driving, compared to that of radio system. Additionally, no significant difference in subjective workload between distractions by mobile app and radio system were found. Several driver characteristics such as experience, driving records, and perception variables also influence driving performances. The findings are expected to facilitate the development of safer ride-hailing systems, as well as driver training and road safety policy

Error distributions assumptions in random regret choice models: towards error components Frechit specifications

Recently introduced regret-based choice models in transportation research have invariably and uncritically adopted the assumption of independently and identically distributed error terms. The central argument underlying this paper is that this assumption is difficult to defend considering the fundamental nature of the concept of regret, which states that regret is generated through the comparison of choice alternatives on an attribute-by-attribute basis. The support this stance, we theoretically and empirically identify and diagnose specification errors in classic regret-based choice models, and provide a solution to remedy the problem. First, we formalize how different sources of error affect the formation of errors. Then, we provide theoretical and empirical evidence that the process of regret generation is irreconcilable with the commonly used assumption of IID Gumbel distributed error terms. Results of formal and empirical analysis comparing classic regret minimizing and linear additive utility maximizing models indicate that measurement error causes identical errors in utility-maximizing models but non-identical errors in regret-minimizing models. Omitted variables cause alternative specific and independent errors in utility-maximizing models, but pairs of alternatives specific and non-independent errors in regret-minimizing models. Finally, accounting for these findings, we suggest a general expression for the error terms of regret-based choice models as a solution for the stipulated problem

Effects of collision warning characteristics on driving behaviors and safety in connected vehicle environments

With the emerging connected vehicle (CV) technologies, a novel in-vehicle omni-direction collision warning system (OCWS) is developed. For example, vehicles approaching from different directions can be detected, and advanced collision warnings caused by vehicles approaching from different directions can be provided. Effectiveness of OCWS in reducing crash and injury related to forward, rear-end and lateral collision is recognized. However, it is rare that the effects of collision warning characteristics including collision types and warning types on micro-level driver behaviors and safety performance is assessed. In this study, variations in drivers’ responses among different collision types and between visual only and visual plus auditory warnings are examined. In addition, moderating effects by driver characteristics including drivers’ demographics, years of driving experience, and annual driving distance are also considered. An in-vehicle human–machine interface (HMI) that can provide both visual and auditory warnings for forward, rear-end, and lateral collisions is installed on an instrumented vehicle. 51 drivers participate in the field tests. Performance indicators including relative speed change, time taken to accelerate/decelerate, and maximum lateral displacement are adopted to reflect drivers’ responses to collision warnings. Then, generalized estimation equation (GEE) approach is applied to examine the effects of drivers’ characteristics, collision type, warning type and their interaction on the driving performance. Results indicate that age, year of driving experience, collision type, and warning type can affect the driving performance. Findings should be indicative to the optimal design of in-vehicle HMI and thresholds for the activation of collision warnings that can increase the drivers’ awareness to collision warnings from different directions. Also, implementation of HMI can be customized with respect to individual driver characteristics

Implementation of Safety Management System for Improving Construction Safety Performance: A Structural Equation Modelling Approach

The construction industry contributes to a large proportion of industrial injury and mortality. It is of high importance to evaluate the effectiveness of the Safety Management System (SMS). In particular, it is necessary to compare the quality and level of achievement of SMS and safety performance of a construction project. However, a sizeable sample of construction accidents is often not available. Therefore, possible proxies to indicate the safety performance were established. Moreover, the motivation factors which characterize the quality and level of achievement should be identified. In this study, a structural model has been established to examine the relationship between the SMS implementation and operational & safety performance of the construction projects. Results of the structural model illustrated the relationship between (i) SMS implementation and project safety outcome, (ii) SMS implementation and five motivation factors, and (iii) project safety outcome and six proxies. Results of this study have unfolded the motivation factors in SMS implementation and their subsequent effects on project performance, throwing light on the need to enhance the safety management practice in order to reduce accidents and injuries in the construction industry in the long run