Analysis of effects of driver’s evasive action time on rear-end collision risk using a driving simulator

Introduction: Driver’s evasive action is closely associated with collision risk in a critical traffic event. To quantify collision risk, surrogate safety measures (SSMs) have been estimated using vehicle trajectories. However, vehicle trajectories cannot clearly capture presence and time of driver’s evasive action. Thus, this study determines the driver’s evasive action based on his/her use of accelerator and brake pedals, and analyzes the effects of the driver’s evasive action time (i.e., duration of evasive action) on rear-end collision risk. Method: Fifty drivers’ car-following behavior on a freeway was observed using a driving simulator. An SSM called “Deceleration Rate to Avoid Crash (DRAC)” and the evasive action time were determined for each driver using the data from the driving simulator. Each driver tested two traffic scenarios – Cars and Trucks scenarios where conflicting vehicles were cars and trucks, respectively. The factors related to DRAC were identified and their effects on DRAC were analyzed using the Generalized Linear Models and random effects models. Results: DRAC decreased with the evasive action time and DRAC was closely related to drivers’ gender and driving experience at the road sections where evasive action to avoid collision was required. DRAC was also significantly different between Cars and Trucks scenarios. The effect of the evasive action time on DRAC varied among different drivers, particularly in the Trucks scenario. Conclusions: Longer evasive action time can significantly reduce crash risk. Driver characteristics are more closely related to effective evasive action in complex driving conditions. Practical Applications: Based on the findings of this study, driver warning information can be developed to alert drivers to take specific evasive action that reduces collision risk in a critical traffic event. The information is likely to reduce the variability of the driver’s evasive action and the speed variations among different drivers.     

Effects of obstacles and deposited coal dust on characteristics of premixed methane–air explosions in a long closed pipe

An experimental system including pressure transducer, electric spark ignition device, data acquisition and control unit was set up to investigate methane–air explosions in a horizontal pipe closed at both ends with or without the presence of obstacles and deposited coal dust. The experimental results show that explosion characteristics depended on the methane content, on the layout of obstacles, and on the deposited coal dust. Pressure fluctuation with a frequency of 150 Hz appeared in its crest when the methane content was close to the stoichiometric ratio (9.5% methane percentage by volume). The pressure rise rate increased locally when a single obstacle was mounted in the pipe, but it had little effect on the pressure peak. Repeated obstacles mounted in the pipe caused the pressure to rise sharply, and the mean maximum explosion overpressure increased with the increase of the obstacle’s number. The amplitude of pressure fluctuation was reduced when deposited coal dust was paved in the bottom of the pipe. However, when repeated obstacles were arranged inside, the maximum overpressures were higher with coal dust deposited than pure gas explosions.     

The effect of orifice plates with different shapes on explosion propagation of premixed methane–air in a semi-confined pipeline

The effect of internal shape of obstacles on the deflagration of premixed methane–air (concentration of 10%) was experimentally investigated in a semi-confined steel pipeline (with a square cross section size of 80 mm × 80 mm and 4 m long). The obstacles used in this study were circular, square, triangular and gear-shaped (4-teeth, 6-teeth and 8-teeth) orifice plates with a blockage ratio of 75%, and the perimeter of the orifice was regarded as a criterion for determining the sharpness of the orifice plate. The overpressure history, flame intensity histories, flame front propagation speed, maximum flame intensity and peak explosion overpressure were analyzed. The explosion in the pipeline can be divided into two stages: initial explosion and secondary explosion. The secondary explosion is caused by recoiled flame. The perimeter is positively related to the intensity of the recoiled flame and the ability of orifice plate to suppress the explosion propagation. In addition, the increase in the perimeter will cause the acceleration of the flame passing through the orifice plate, while after the perimeter of the orifice reaches a certain value, the effect of the increase in perimeter on explosion excitation becomes no obvious. The overpressure (static pressure) downstream of the orifice plate is the result of the combined effect of explosion intensity and turbulence. The increase in perimeter leads to the increase in turbulence downstream of the orifice plate which in turn causes more explosion pressure to be converted into dynamic pressure.     

Effect of ignition position on vented hydrogen–air deflagration in a 1 m3 vessel

This study investigates the effect of the ignition position on vented hydrogen-air deflagration in a 1 m³ vessel and evaluates the performance of the commercial computational fluid dynamics (CFD) code FLACS in simulating the vented explosion of hydrogen-air mixtures. First, the differences in the measured pressure-time histories for various ignition locations are presented, and the mechanisms responsible for the generation of different pressure peaks are explained, along with the flame behavior. Secondly, the CFD software FLACS is assessed against the experimental data. The characteristic phenomena of vented explosion are observed for hydrogen-air mixtures ignited at different ignition positions, such as Helmholtz oscillation for front ignition, the interaction between external explosion and combustion inside the vessel for central ignition, and the wall effect for back-wall ignition. Flame-acoustic interaction are observed in all cases, particularly in those of front ignition and very lean hydrogen-air mixtures. The predicted flame behavior agree well with the experimental data in general while the simulated maximum overpressures are larger than the experimental values by a factor of 1.5–2, which is conservative then would lead to a safe design of explosion panels for instance. Not only the flame development during the deflagration was well-simulated for the different ignition locations, but also the correspondence between the pressure transients and flame behavior was also accurately calculated. The comparison of the predicted results with the experimental data shows the performance of FLACS to model vented mixtures of hydrogen with air ignited in a lab scale vessel. However, the experimental scale is often smaller than that used in practical scenarios, such as hydrogen refueling installations. Thus, future large-scale experiments are necessary to assess the performance of FLACS in practical use.     

Should 'Cyrus the Centipede' take a hike? Effects of exposure to a pedestrian safety program on children's safety knowledge and self-reported behaviors

INTRODUCTION: We report the first evaluation of the popular "Cyrus the Centipede" child pedestrian safety program. METHOD: A pre-test/post-test control versus experimental condition design was used to assess Cyrus' impact on third graders' pedestrian safety knowledge, and self-reported pedestrian behaviors. RESULTS: Although some beneficial effects were observed, the program was not reliably effective. In particular, the impact of exposure to Cyrus was strongly influenced by the individual teacher who delivered it, likely due to the highly unstructured nature of the curriculum. SUMMARY: We suggest that: (a) the effectiveness and reliability of such programs be demonstrated before they are widely adopted; and (b) programs that focus on training children in actual or simulated traffic environments may be more effective than those that primarily focus on teaching safety facts and rules.     

One,two or three dimensions of work engagement? Testing the factorial validity of the Utrecht Work Engagement Scale on a sample of Polish employees

Work engagement, as conceptualized by the Utrecht Work Engagement Scale (UWES), is a work-related positive state of mind that is characterized by vigour, dedication and absorption; however, it still remains unclear how many dimensions work engagement comprises. This study tested the factorial validity of 11 different UWES factorial models that are available in the literature using a confirmatory factor analysis approach on a large sample of multi-occupational Polish employees (N?=?1420). The two-factor UWES-6, comprising vigour and dedication, was found to be reliable and remained invariant across samples drawn from four different organizational positions. It also presented a better fit than the three-factor UWES-9, which is a scale used as a standard in contemporary research on work engagement. The findings suggest that the three-factor UWES-9 might not be an optimal measure of work engagement in Poland.     

Response to commentary on “The Driver Behaviour Questionnaire as a predictor of accidents: A meta-analysis”

A commentary on our previously published meta-analysis about the predictive validity of the Driver Behaviour Questionnaire (DBQ) raised a number of points. These points do not dispute the quantitative results as such, but suggest that our introduction and discussion overly favor the DBQ and are incomplete in a number of ways. The commentary targeted the following topics: common method variance, intercorrelations of different instruments, accident data validity, correcting for measurement error,

Common method variance

Our meta-analysis provided an extensive discussion of validity threats, including ones not treated before in the DBQ literature, such as common scale anchors and publication bias. We see little added value in the commentary when it informs the readership of common method variance (CMV), as we clearly did this in our article. It is widely understood that CMV can account for a large share of the variance when self-reported data are intercorrelated (see Podsakoff, MacKenzie, Lee, & Podsakoff, 2003

Intercorrelations of different instruments

The commentary reacts to an introductory sentence in which we stated that the DBQ is strongly situated in a network of other questionnaires and tests (such as Trait Anxiety, Cognitive Failures Questionnaire, and Sensation Seeking Scale), by asserting that we seem to interpret such correlations as a positive feature of the DBQ and by pointing out that correlations between the DBQ and other self-reports may have arisen spuriously because of CMV.We dispute the assertion that we regard correlations

Accident data validity

The commentary rejects our position that not only self-reported accident data are susceptible to biases, but recorded data too. Note that our remark applied to all types of recorded accidents, including police reports, hospital data, insurance data, as well as fleet data from professional drivers, and not just company data as in the work by af Wåhlberg, Dorn, and Kline (2011), which is mentioned in the commentary. The literature discusses several sources of bias for recorded accidents that are

Correcting for unreliability

The commentary pointed out that our correction for attenuation is unusual, a surprising claim considering the established importance of correction for measurement error in theory testing (Liu and Salvendy, 2009, Schmidt and Hunter, 1999). The available DBQ research provided almost no information on measurement error, so we did not apply a correction as part of the meta-analysis. Instead, we applied one afterwards, based on the raw data of the largest DBQ study available, and illustrated that

Exposure

The commentary points out that our results were not corrected for exposure in any way. First of all, this statement is false, because our meta-analysis did include effect sizes corrected for exposure. We used a special moderator category for effect sizes other than zero-order correlations. These effect sizes were derived from regression analysis, often with mileage as one of the predictors.Second, it may be noted that af Wåhlberg himself reported that the association between exposure and

Further references

The commentary attended us to 11 studies supposedly not included in our meta-analysis. We appreciate af Wåhlberg and Dorn's close scrutiny of our reference list for potential omissions on the DBQ-accident relationship. It may be noted that missing a small fraction of studies in a meta-analysis of this scope is almost inevitable.The samples of four of the studies (Dobson et al., 1999, Elliott et al., 2007, Parker, 1999, Stradling et al., 2005) identified in the commentary were already included

Discussion

The purpose of a meta-analysis is to provide a quantitative summary of a metric of interest, correlations between the DBQ, and external criteria in our case. af Wåhlberg and Dorn's commentary does not dispute the quantitative results in themselves (except with regard to the correction for exposure), but targets the qualitative introduction and discussion of our article.The commentary raises some valid points, albeit points already discussed in our article. We too believe that common method

     

The Effectiveness of a “Break Experiment” from a Long-Term Perspective

The study reports the results of a follow-up evaluation, conducted in 1994, of the impact of a training program for female unskilled metal workers that was implemented at the end of the 1970s. The program was designed to promote occupational skills development, and was first evaluated in 1979. On both occasions of evaluation the investment in training was examined from two perspectives, those of the training participants and management. Data were collected through semistructured personal interviews with key members of personnel management and through a group conversation session with a majority of the original course attendees. Supplementary background information was obtained from documents and records maintained by the organization. At some points, there was a convergence of views on the significance of the training program for occupational skills development, at others a divergence. These convergences and divergences are finally discussed and the findings of the study are related to other research on this particular kind of intervention.     

Effects of work surface and task difficulty on neck–shoulder posture and trapezius activity during a simulated mouse task

Objectives. The purpose of this study is to evaluate the influence of the work surface and task difficulty on the head, upper back and upper arm postures and activity of the descending trapezius during a simulated mouse task. Methods. Healthy female university students (N?=?15) were evaluated. The work surface was positioned at elbow height (EH) and above elbow height (AEH) and the task difficulty was set at low (LD) and high (HD) levels. The postures were recorded by inclinometers. Trapezius activity was normalized by the maximum voluntary isometric contraction (MVIC). Results. Significantly higher head flexion was found at EH compared to the AEH condition, with an average difference of 2°–5° at the same difficulty level. The HD task significantly increased head (3°–6°) and upper back flexion (6°–7°) at the same table height. For upper arm elevation and trapezius activation, the AEH condition presented higher upper arm elevation (about 6°–8°) and trapezius activity (0.8–1.4% of MVIC), regardless of the difficulty level of the task. Conclusions. Head posture was influenced by the table height and task difficulty; the upper back posture by high difficulty; and upper arm posture and trapezius activity were only influenced by table height.     

Effect of Aging on Brain Injury Prediction in Rotational Head Trauma—A Parameter Study with a Rat Finite Element Model

Objective: The aim of this study was to investigate the possible effects of age-related intracranial changes on the potential outcome of diffuse axonal injuries and acute subdural hematoma under rotational head loading.

Methods: A simulation-based parametric study was conducted using an updated and validated finite element model of a rat head. The validation included a comparison of predicted brain cortex sliding with respect to the skull. Further, model material properties were modified to account for aging; predicted tissue strains were compared with experimental data in which groups of rats in 2 different lifecycle stages, young adult and mature adult, were subjected to rotational trauma. For the parameter study, 2 age-dependent factors—brain volume and region-specific brain material properties—were implemented into the model. The models young adult and old age were subjected to several injurious and subinjurious sagittal plane rotational acceleration levels.

Results: Sequential analysis of the simulated trauma progression indicates that an increase in acute subdural hematoma injury risk indicator occurs at an early stage of the trauma, whereas an increase in diffuse axonal injury risk indicators occurs at a later stage. Tissue stiffening from young adult to mature adult rats produced an increase in strain-based thresholds accompanied by a wider spread of strain distribution toward the rear part of the brain, consistent with rotational trauma experiments with young adult and mature adult rats. Young adult to old age brain tissue softening and brain atrophy resulted in an increase in diffuse axonal injuries and acute subdural hematoma injury risk indicators, respectively.

Conclusions: The findings presented in this study suggest that age-specific injury thresholds should be developed to enable the development of superior restraint systems for the elderly. The findings also motivate other further studies on age-dependency of head trauma.     

Small-scale fire performance assessment of intumescent coatings on metal tubes containing ammonium nitrate. A stepping-stone towards their application as a fire safety measure on road transportation tanks?

Ammonium nitrate is used in vast amounts globally, first and foremost as a component of fertilizers and explosive formulations. This usage necessitates its transportation which, as for most hazardous materials, involves certain risks. For oxidizing materials such as ammonium nitrate, the ultimate consequence of road transportation incidents is usually considered to be fire followed by explosion. Even though the probability in general is low, substantial reduction in its risk is a great gain for public safety. Thus, identifying novel and improving current safety measures for risk reduction, is an important aspect in the field of hazardous materials. Herein, a series of experiments are reported, which demonstrate the fire protection performance of two state-of-the-art intumescent passive fire protection materials on small-scale metal test tubes containing ammonium nitrate. Albeit being initial experiments on laboratory-scale, these results provide a promising starting point for further investigations on the potential of these materials for the fire protection of ammonium nitrate when carried in metal tanks. At its best, a prominent protection of ammonium nitrate from heat exposure was observed, as the temperature was kept well below its boiling point for more than 2.5 h. Successively, it resulted in a complete recovery of the sample material. This was in large contrast to the observed results for the unprotected test tubes, which led to complete decomposition of the sample after 11 min.     

Assessment of the effect of welding fumes on welders’ cognitive failure and health-related quality of life

Introduction. This study examined whether cognitive symptoms and health-related quality of life can be affected by welding fume exposure. Method. Participants consisted of welders (n?=?40) and welder assistants (n?=?25) from welding units as the exposed group, and office workers (n?=?44) as the non-exposed group. All participants were studied using ambient air monitoring and two types of questionnaires: the Cognitive Failures Questionnaire (CFQ) and the 36-item Short Form Health Survey (SF-36). Results. Welders and welder assistants were exposed to higher concentrations of all airborne metals than office employees, except for aluminum and chromium (p?p?M (SD)?=?54.84 (17.88)). The relationships between total CFQ score and the measured concentration of nickel at peak work rate was significant for welders. Conclusion. Cognitive symptoms and health-related quality of life were not related to the measures of welding fume exposure and further research should be performed to find other influencing factors.     

Investigation of affecting parameters on treating high-strength compost leachate in a hybrid EGSB and fixed-bed reactor followed by electrocoagulation–flotation process

In this research, treatability of high-load compost leachate in a hybrid expanded granular sludge bed (EGSB) and fixed-bed (FB) bioreactor followed by electrocoagulation–flotation (ECF) system was examined. The operational factors in EGSB–FB were influent chemical oxygen demand (COD), hydraulic retention time (HRT) and COD/nitrogen ratio (COD/N). And, their interactive effects on the efficiency of COD removal and biogas production rate (BPR) as responses were analyzed and correlated by response surface methodology (RSM). The optimum conditions of the hybrid EGSB–FB reactor were acquired at COD = 7800 mg/L, HRT = 35 h, COD/N = 70, in which COD removal efficiency was 83% and BPR 94 mL/h. The amount of confidence interval was 95%. COD (relevant coefficient = 9.8) and HRT (relevant coefficient = −24) were resulted respectively as the most effective parameters on COD removal and BPR. Yet, COD/N parameter imposed negative effect on COD removal and BPR in values less than about 100. The outcomes indicated that operated ECF as post-treatment in constant conditions (electrolysis time = 75 min, electrodes distance = 3 cm, voltage = 20 V) successfully satisfied discharge criteria in the most part of experimental domains.     

The analysis of influence of individual and environmental factors on 2-wheeled users’ injuries

Objective: Powered 2-wheeled motor vehicles (PTWs) are one of the most vulnerable categories of road users. Bearing that fact in mind, we have researched the effects of individual and environmental factors on the severity and type of injuries of PTW users. The aim was to recognize the circumstances that cause these accidents and take some preventive actions that would improve the level of road safety for PTWs.

Methods: In the period from 2001 to 2010, an analysis of 139 road accidents involving PTWs was made by the Faculty of Transport and Traffic Engineering in Belgrade. The effects of both individual (age, gender, etc.) and environmental factors (place of an accident, time of day, etc.) on the cause of accidents and severity and type of injuries of PTWs are reported in this article. Analyses of these effects were conducted using logistic regression, chi-square tests, and Pearson's correlation.

Results: Factors such as categories of road users, pavement conditions, place of accident, age, and time of day have a statistically significant effect on PTW injuries, whereas other factors (gender, road type; that is, straight or curvy) do not. The article also defines the interdependence of the occurrence of particular injuries at certain speeds. The results show that if PTW users died of a head injury, these were usually concurrent with chest injuries, injuries to internal organs, and limb injuries.

Conclusions: It has been shown that there is a high degree of influence of individual factors on the occurrence of accidents involving 2-wheelers (PTWs/bicycles) but with no statistically significant relation. Establishing the existence of such conditionalities enables identifying and defining factors that have an impact on the occurrence of traffic accidents involving bicyclists or PTWs. Such a link between individual factors and the occurrence of accidents makes it possible for system managers to take appropriate actions aimed at certain categories of 2-wheelers in order to reduce casualties in a particular area. The analysis showed that most of the road factors do not have a statistically significant effect on either category of 2-wheeler. Namely, the logistic regression analysis showed that there is a statistically significant effect of the place of accident on the occurrence of accidents involving bicyclists.     

Biomechanical Consequences of the Hand’s Action on Unstable Handle

The concept of muscular stabilization refers to imposing active muscular constraints on the joint degrees of freedom that are not used in a given motor task and the stabilization of unstable working objects. The human organism bears considerable cost due to the realization of this process, which in the case of muscular static force developed in relation to an unstable working object reaches approximately 24%. The aim of this article is twofold: (a) to determine the useful efficiency of the hand-working object system with an unstable handle in relation to the released muscular force and power dynamics and (b) to identify the relative contribution of the upper extremity muscles engaged in the realization of motor or stabilizing functions in the electromyography (EMG) sphere.     

Effects of cross-wise obstacle position on methane–air deflagration characteristics

A vented chamber, with internal dimensions of 150 mm × 150 mm × 500 mm, is constructed in which the premixed methane–air deflagration flame, propagating away from the ignition source, interacts with obstacles along its path. Three obstacle configurations with different cross-wise positions are investigated. The cross-wise obstacle positions are found to have significant effects on deflagration characteristics, such as flame structure, flame front location, flame speed, and overpressure transients. The rate of flame acceleration, as the flame passes over the last obstacle, is the highest at the configuration with three centrally located obstacles, whereas the lowest is observed at the configuration with three obstacles mounted on one side of the chamber. Compared with the side configuration, the magnitude of overpressure generated increases by approximately 80% and 165% for the central and staggered configurations, respectively. Furthermore, flame propagation speeds and generated overpressures for both the central and staggered configurations are greater, which should to be avoided to reduce the risk associated with turbulent premixed deflagrations in practical processes.     

The unintended impact of helmet use on bicyclists’ risk-taking behaviors

Introduction: Safety is a critical factor in promoting sustainable urban non-motorized travel modes like bicycles. Helmets have shown to be effective in reducing injury severity in bicycle crashes, however, their effects on bicyclists’ behaviors still requires deeper understanding, especially amid the emerging trend of using shared bicycles. Risk compensation effects suggest that bicyclists may offset perceived gains in safety from wearing a helmet by increasing risk-taking behaviors. A better understanding of these compensation effects can be useful in assessing various bicycle safety related programs. Method: Using a sample of 131 bicyclists from the San Francisco Bay area, this research studies how bicyclists respond with respect to risk-taking behaviors under various urban-street conditions, as a function of helmet use. Study participants were each shown 12 videos, shot in Berkeley, California, from the perspective of a bicyclist riding behind another bicyclist. A fractional factorial experiment design was used to systematically vary contextual attributes (e.g., speed, bike lane facilities, on-street parking, passing vehicles) across the videos. After each video, participants were asked to indicate if they would overtake the bicyclist in the video. With the help of data adaptive estimation techniques, targeted maximum likelihood estimation (TMLE) was applied to estimate the average risk difference between helmeted users and non-users, controlling for self-selection effects. Individual-based nonparametric bootstrap was performed to assess the uncertainty associated with the estimator. Results: Our findings suggest, on average, individuals more likely to wear a helmet are 15.6% more likely to undertake a risky overtaking maneuver. Practical Applications: This study doesn’t try to oppose mandatory helmet laws, but rather serves as a cautionary warning that road safety programs may need to consider strategies in which unintended impact of bicycle helmet use can be mitigated. Moreover, our findings also provide additional evaluation component when it comes to the cost-benefit assessment of helmet-related laws.     

Effects of initial temperature and pressure on explosion characteristics of propane–diluent–air mixtures

The explosion characteristics of propane–diluent–air mixtures under various temperatures and pressures were investigated using a 20-L apparatus. The explosion limits of propane diluted with nitrogen or carbon dioxide were measured at high temperatures from 25 to 120 °C. The results showed that the upper explosion limit (UEL) increased, and the lower explosion limit (LEL) decreased with the rising temperature. The explosion limits of propane diluted with nitrogen or carbon dioxide were also measured at high pressures from 0.10 to 0.16 MPa. The results showed that the UEL increased, and the LEL almost remainedunchanged along with increased pressure. Under the same initial operating conditions, the concentration of nitrogen required to reach the minimum inerting concentration (MIC) point was higher than the concentration of carbon dioxide. Finally, the study investigated the limiting oxygen concentration (LOC) of propane under various initial temperatures, initial pressures, and inert gases. The LOC of propane decreased approximately linearly with increased temperature or pressure, and the LOC of propane dilution with carbon dioxide was greater than dilution with nitrogen from 25 to 120 °C or from 0.10 to 0.16 MPa, which indicated that the dilution effect of carbon dioxide was better than that of nitrogen.