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Monotony of road environment and driver fatigue: a simulator study.

Studies have shown that drowsiness and hypovigilance frequently occur during highway driving and that they may have serious implications in terms of accident causation. This paper focuses on the task induced factors that are involved in the development of these phenomena. A driving simulator study was conducted in order to evaluate the impact of the monotony of roadside visual stimulation using a steering wheel movement (SWM) analysis procedure. Fifty-six male subjects each drove during two different 40-min periods. In one case, roadside visual stimuli were essentially repetitive and monotonous, while in the other one, the environment contained disparate visual elements aiming to disrupt monotony without changing road geometry. Subject's driving performance was compared across these conditions in order to determine whether disruptions of monotony can have a positive effect and help alleviate driver fatigue. Results reveal an early time-on-task effect on driving performance for both driving periods and more frequent large SWM when driving in the more monotonous road environment, which implies greater fatigue and vigilance decrements. Implications in terms of environmental countermeasures for driver fatigue are discussed.

Accidents, Traffic↗

An accident waiting to happen: a spatial approach to proactive pedestrian planning.

There are about 75,000 pedestrian crashes in the United States each year. Approximately 5000 of these crashes are fatal, accounting for 12% of all roadway deaths. On college campuses, pedestrian exposure and crash-risk can be quite high. Therefore, we analyzed pedestrian crashes on the campus of the University of North Carolina at Chapel Hill (UNC) as a test case for our spatially-oriented prototype tool that combines perceived-risk (survey) data with police-reported crash data to obtain a more complete picture of pedestrian crash-risk. We use spatial analysis techniques combined with regression models to understand factors associated with risk. The spatial analysis is based on comparing two distributions, i.e. the locations of perceived-risk with police-reported crash locations. The differences between the two distributions are statistically significant, implying that certain locations on campus are perceived as dangerous, though pedestrian crashes have not yet occurred there, and there are actual locations of police-reported crashes that are not perceived to be dangerous by pedestrians or drivers. Furthermore, we estimate negative binomial regression models to combine pedestrian and automobile exposure with roadway characteristics and spatial/land use information. The models show that high exposure, incomplete sidewalks and high crosswalk density are associated with greater observed and perceived pedestrian crash-risk. Additionally, we found that people perceive a lower risk near university libraries, stadiums, and academic buildings, despite the occurrence of crashes.

Accidents, Traffic↗

Driver behaviour during flashing green before amber: a comparative study.

The paper discusses the results of extensive measurements of drivers' stopping behaviour during signal programmes with and without flashing green before amber. Ten locations in Switzerland, Austria, and Germany were recorded with a video camera and analysed using an image-processing system. About 5000 cycles were documented. The analysis shows that the flashing green increases the number of early stops, as drivers tend to underestimate the duration of the time to the end of amber. Discrete choice models of the stopping behaviour are estimated for inclusion in suitable microsimulation models of traffic flow. The model results show that speed and distance to stop line, and their interaction (potential time to the stop line with unchanged speed) explain the stopping process.

Austria↗

Estimating the risk of collisions between bicycles and motor vehicles at signalized intersections.

Collisions between bicycles and motor vehicles have caused severe life and property losses in many countries. The majority of bicycle-motor vehicle (BMV) accidents occur at intersections. In order to reduce the number of BMV accidents at intersections, a substantial understanding of the causal factors for the collisions is required. In this study, intersection BMV accidents were classified into three types based on the movements of the involved motor vehicles and bicycles. The three BMV accident classifications were through motor vehicle related collisions, left-turn motor vehicle related collisions, and right-turn motor vehicle related collisions. A methodology for estimating these BMV accident risks was developed based on probability theory. A significant difference between this proposed methodology and most current approaches is that the proposed approach explicitly relates the risk of each specific BMV accident type to its related flows. The methodology was demonstrated using a 4-year (1992-1995) data set collected from 115 signalized intersections in the Tokyo Metropolitan area. This data set contains BMV accident data, bicycle flow data, motor vehicle flow data, traffic control data, and geometric data for each intersection approach. For each BMV risk model, an independent explanatory variable set was chosen according to the characteristics of the accident type. Three negative binomial regression models (one corresponding to each BMV accident type) were estimated using the maximum likelihood method. The coefficient value and its significance level were estimated for each selected variable. The negative binomial dispersion parameters for all the three models were significant at 0.01 levels. This supported the choice of the negative binomial regression over the Poisson regression for the quantitative analyses in this study.

Accidents, Traffic↗

The impact of speed and other variables on pedestrian safety in Maine.

The aim of this paper is to analyze pedestrian crashes with an emphasis on how actual travel speeds and characteristics of the locations influence crash numbers. Statewide data from Maine was analyzed. Descriptive crash and behavioral statistics are presented in the paper. Pedestrian and vehicle volumes were gathered for 122 locations in varying environments throughout Maine and crash numbers were predicted and compared to outcomes. Prediction models from Sweden and the UK were used since US models are nonexistant. It was found that high speeds and wide roads lead to more crashes and that the focus of safety improvement should be on arterials and major collectors. A strong relationship was also found between crash severity and speed.

Accidents, Traffic↗

Policy issues and risk-benefit trade-offs of 'safer surfacing' for children's playgrounds.

The case for the universal application of 'safer surfacing' in playgrounds is assessed in terms of absolute risk, cost-benefit, and qualitative factors, and found to be open to question on each front. In parallel, it is noted that members of the child welfare and play communities are increasingly of the view that playgrounds are losing their appeal for children, which in turn has its own health, safety and developmental consequences. In part, this loss of attractiveness may have linkages with the recent concern over play safety and the imposition of measures such as 'safer surfacing'. It is proposed that the drive for play safety, which has existed for some 20 years, should be succeeded by a more holistic approach which, rather than considering play safety in isolation, acknowledges the importance of all attributes of play including child safety both on and off playgrounds, potential beneficial aspects of childhood risk exposure, adventure, and play value.

Adolescent↗

Are suicides by jumping off bridges preventable? An analysis of 50 cases from Sweden.

This is a community-based sequential case series of 50 individuals who committed suicide by jumping from bridges in two regions of Sweden. Of the 50 subjects, 32 were men and 18 women, with a median age of 35 years. At least 40 had psychiatric problems. The frequency of suicide was highest during the summer months and during the weekends. A total of 27 bridges were used, with a total length of just under 9 km. Three bridges accounted for almost half of all suicides. Limiting the availability of one method of committing suicide is reported to reduce the overall suicide rate; why suicide and injury suicide preventive measures might be considered. Since this study demonstrates that few bridges attract suicide candidates, this injury mechanism needs to be acknowledged by the road system owners and included in the safety work.

Adolescent↗

The effects of an edgeline on speed and lateral position: a meta-analysis.

This paper presents a meta-analysis of studies that have evaluated the effects of an edgeline on speed and lateral position of motorised road users. Together with many other study characteristics, 41 estimates of the effects of an edgeline on speed and 65 on lateral position were extracted from the studies. The results of the evaluation studies show a great variety in effects. Both negative and positive effects on speed and lateral position were found; amongst others, increases in speed up to 10.6 km/h, as well as decreases in speed up to 5.0 km/h, and shifts of the lateral position towards the centre of the road up to 30 cm, as well as shifts towards the edge of the road up to 35 cm. Further analyses resulted in the determination of study characteristics that influence the effects of an edgeline on speed and lateral position. It is concluded that the effects of an edgeline on speed are related to the presence of a centreline. Applying an edgeline to a road without a centreline increases the speed of road users, and replacing a centreline by an edgeline decreases the speed. Results with respect to adding an edgeline to a road with a centreline were unclear. Another conclusion is that shoulder width and road environment contribute to the effects of an edgeline on lateral position. In combination with wide shoulders or buildings and/or trees next to the road, edgelines lead to shifts of the lateral position towards the edge of the road, and in combination with narrow shoulders or open fields, edgelines lead to shifts towards the centre of the road.

Accidents, Traffic↗

Accident prediction models for roads with minor junctions.

The purpose of this study was to develop and validate a method for predicting expected accidents on main roads with minor junctions where traffic counts on the minor approaches are not available. The study was based on data for some 3800 km of highway in the U.K. including more than 5000 minor junctions. The highways consisted of both single and dual-carriageway roads in urban and rural areas. Generalized linear modelling was used to develop regression estimates of expected accidents for six highway categories and an empirical Bayes procedure was used to improve these estimates by combining them with accident counts. Accidents on highway sections were shown to be a non-linear function of exposure and minor junction frequency. For the purposes of estimating expected accidents, while the regression model estimates were shown to be preferable to accident counts, the best results were obtained using the empirical Bayes method. The latter was the only method that produced unbiased estimates of expected accidents for high-risk sites.

Accidents, Traffic↗

Conflicting goals of skid training.

Efforts to make novice drivers drive more safely on slippery roads by means of special courses have mainly failed. In order to understand why the courses have failed, the views of instructors and students on the goals of skid training courses were compared. The importance given to anticipating vs manoeuvring skills was analysed. After completing a skid training course, students in four Nordic countries (Denmark, Finland, Norway and Sweden) assessed manoeuvring skills to be equally important to anticipating skills in the courses. However, instructors assessed anticipating skills to be more important than manoeuvring skills. The differences between the assessments of instructors and students were the same in all four countries. Manoeuvring exercises are widely used in the courses although the main purpose of these courses is to develop anticipating skills. The exercises may give students the impression that manoeuvring skills are more important than anticipating skills. Manoeuvring exercises also increase their self-confidence and may lead to underestimation of the risks involved, resulting in e.g. driving at higher speed.

Accidents, Traffic↗

Conflict analysis for prediction of fatal crash locations in mixed traffic streams.

This paper reports the results of a study that explored the relationship between fatal crashes and conflict rates at mid-block on 14 locations in Delhi, India. All locations had a mix of motorized and non-motorized traffic. The sites were selected to represent low, medium and high fatality rates. The analysis was done in two stages. The first stage used recent 3-year statistics along the entire street. The second stage focused on each fatal crash for mid-block segments on those streets. Peak-hour traffic at 14 selected locations was videotaped. Trained observers recorded traffic compositions at mid-block, average space mean speeds by mode and conflicts by type, reactor mode and cause mode. After converting raw conflict counts to rates, site ranking went from high to low conflict rate sites. The studies showed a weak crash-conflict association. Conflict data for various sites were compared for different combinations of conflicts. The comparison revealed that the presence of only a few non-motorized modes is enough to cause conflicts between motorized vehicles and on-road non-motorized vehicles. The study did not provide a conclusive relationship between mid-block conflicts and fatal crash sites. However, the conflict study provided useful insights into the interaction between different traffic entities in the traffic streams of 14 sites. An important conclusion of this study is that a traffic-planning emphasis on studying conflict rates may not result in reducing fatality rates on urban roads along mid-block segments.

Accident Prevention↗

The influence of trend on estimates of accidents at junctions.

While reliable estimates of expected accidents can be achieved by combining observed accidents and accident model predictions using an empirical Bayes approach, there are a number of obstacles to the widespread adoption of the method. This paper concentrates on problems associated with the available predictive models. Of particular concern is the effect on model predictions of accident trends over time resulting from, for instance, traffic growth or national road safety programmes. Since accident models invariably include traffic flow as an explanatory variable, the effects of flow changes can be included provided that account is taken of the nonlinear relationship between accidents and exposure. It is, however, common to assume that accident risk per unit of exposure is constant over time, whereas national data imply that accident risk is declining. In addition, there is a need, in practice, to rank and evaluate remedial sites in terms of the specific accident types or severities which might be targeted by treatment (for example, wet road accidents in the case of surface treatment). This then raises the question of whether the proportions of accidents of various types varies over time or with traffic flow and site characteristics. Generalized linear modelling was used to develop regression estimates of expected junction accidents (both in total and disaggregated by severity, road surface condition and lighting condition) which allow for the possibility of accident risk varying over time. Accident risk at the sample of some 500 junctions was shown to be declining annually by an average of 6%, with no significant difference in the value of trend between accident types. The factors which affected the proportions of accidents of various types included the method of junction control, speed limit and traffic flow.

Accidents, Traffic↗

Furniture tipping accidents: redesign for prevention.

A large public service organization was concerned with protection of its customers against hazards associated with furniture tipping in public use concourses. Because no injury experience was available for analysis, hazard patterns for tipping accidents were developed from an observational study of public interaction with the furniture. For each hazard pattern, anthropometric models were used to find the probability of the furniture being safe from tipping, for different age and gender combinations. A safety criterion was developed from this modeling, and used to change the weights of some furniture items to resist tipping. These modifications have now been implemented and are in widespread use. Implications for broader application of these models to the development of valid tipping standards for furniture are discussed.

Accidental Falls↗

The effect of lane line width and contrast upon lanekeeping.

The combined effect of lane line width and line-pavement contrast upon lanekeeping was studied through simulation. Some 124 subjects, ages 17-79 (x = 56.30), 52% male, each performed 42 trials over road segments representing three levels of width crossed with 14 line-pavement contrast ratios. Lanekeeping performance was recorded in terms of heading error, position error, lane excursions and road excursions. Subjects were stratified into two levels of ability on a combined measure of visual, attentional and psychomotor variables known to decline with age. Contrast and width had a negligible effect upon performance except at very low contrast ratios, ca 1.02 at high pavement luminance levels (e.g. concrete) and 1.04 for very low luminance levels (e.g. asphalt). These ratios are similar to those encountered at night on wet roads. Mean overall performance error at the low contrast ratios increased by a factor of 1.6, 1.8 and 2.2 for 8, 6 and 4" widths, respectively. Lower ability subjects exhibited greater error at almost all contrast ratios, with no consistent relationship between degree of decrement and either width or contrast. The results suggest that lane line width and contrast have a negligible effect upon lanekeeping performance except at extremely low levels of contrast, where both have large effects. Further research in the roadway environment is needed to determine the relationships of line width and contrast ratio to lanekeeping on normal and degraded surface conditions.

Accidents, Traffic↗

Production economics analysis of investment initiated to improve working environment.

This article describes the results of an evaluation of a new work place for ladle preparation at Swedish Steel in Luleå, Sweden. The company initiated a development project related to ladle service work, in order to come to grips with the difficult working environment and problems associated with absenteeism due to illness and occupational injuries. The evaluation was performed for the first three years after implementation of the project and it shows that the new work place considerably improved working conditions and increased both the quality and efficiency of production. The purpose of this article is also to discuss some methodological problems. The follow-up of the various changes in working environment and personnel statistics was fairly simple to carry out. But in terms of production effects, the company's in-house production follow-up system proved to be too unspecified and oversimplified. It was also difficult to decide which changes should count as effects of the new work place and to value these in monetary terms. The profitability calculation shows that an investment initiated to improve the working environment can yield good profitability.

Cost Savings↗

Prospective memory: a secondary task with promise.

This paper examines the utility of prospective memory as a secondary task. For this purpose, the results of seven experiments were analysed to evaluate the sensitivity of prospective memory, making a direct comparison with another secondary task (reaction time). Both tasks were used as subsidiary elements in a complex task environment, the design of which was based on the micro-world research paradigm. The results indicated that prospective memory was slightly more vulnerable to variations in experimental conditions than was reaction time. The paper concludes that, overall, prospective memory appears to be a suitable secondary task. This is partly attributed to the element of self-initiation, which is a feature of some prospective memory tasks. It is recommended to use time-based and pulse-based prospective memory tasks since they seem to be the more sensitive.

Humans↗

Ergonomics.

Ergonomics is the application of natural laws governing human work in order to maximize safety and efficiency in the workplace. Ergonomic assessment includes job analysis from the biomechanical, physiologic, and physical viewpoints. The three most commonly described categories of ergonomic intervention are worker training, worker selection, and job redesign. In the last analysis, workplace redesign, using both engineering and administrative methods, is likely to be the most effective intervention.

Biomechanical Phenomena↗

Enriched environment during development is protective against lead-induced neurotoxicity.

It is known that children of lower socioeconomic status have a disproportionately higher risk of being exposed to lead and have a more negative outcome from that exposure than children who are raised under more fortunate circumstances. Yet, little is known about how environmental factors may influence the injurious effects on the brain of a neurotoxin such as lead. The present study used an animal model of lead poisoning to examine the extent to which different environmental milieus may modify the effects of lead on the developing brain. Young rats were raised in either enriched or impoverished environments and drank either distilled water or water with lead. Lead-exposed rats raised in the impoverished environment had spatial learning deficits and significantly decreased neurotrophic factor gene expression in the hippocampus. In contrast, the animals raised in the enriched environment were significantly protected against the behavioral and neurochemical toxicity of lead. These results demonstrate that impoverished environment may accentuate while enriched environment may ameliorate neurobehavioral and neurochemical toxicity from developmental lead exposure.

Animals↗