A field assessment of floor slipperiness in a fish market in Taiwan

A field assessment of floor slipperiness in 10 fish stands in a fish market in Taiwan was conducted using both friction measurements and subjective ratings. The friction measurements were conducted using the Portable Skid Resistance Tester (PSRT). The subjective ratings of floor slipperiness of both the workers and the customers were collected. The friction measurement results showed that the sink areas had both the lowest friction values and subjective ratings. The overall friction measurement results and the subjective ratings were in fair agreement (r = 0.46 and ρ = 0.49). The customers perceived the walkways as somewhere between “very slippery” to “somewhat slippery” and the picking-up areas as “very slippery.” These were different from the perceptions of the workers where they perceived both areas as “somewhat slippery.”     

Subjective assessments of floor slipperiness before and after walk under two lighting conditions

A gait experiment was performed. The participants were tested under shoes, floors, surface and lighting conditions. They gave floor slipperiness ratings before and after a gait trial. The perceived sense of slip (PSOS) was collected. It was found that the perceived floor slipperiness (PFS) before walking was affected significantly by the lighting, floor and surface conditions. Relative low PFS values were recorded under wet and detergent-contaminated conditions in the normal daylight condition as compared with those in the dimmed condition. The PFS after the gait was significantly affected by the floor and surface conditions. The PSOS was highly correlated with the PFS after trial. The regression analyses results indicated that both the coefficient of friction (COF) of the floor and lighting were primary predictors of the PFS before a gait. The COF and walking speed were the primary predictors of the PFS after a gait.     

Preferred surface microscopic geometric features on floors as potential interventions for slip and fall accidents on liquid contaminated surfaces

PROBLEM: Surface roughness affects friction, so selection of floor surfaces with certain roughness characteristics could potentially reduce slip and fall accidents. This article summarizes the preferred surface microscopic geometric features that could increase friction on surfaces covered with liquid contaminants. METHOD: Three types of surface features, represented by the average of the maximum height above the mean line in each cut-off length (R(pm)), the arithmetical average of surface slope (Delta(a)), and the kernel roughness depth (R(k)), are identified as preferred surface microscopic geometric features for a higher friction. The proper settings on the profilometers (instruments used to measure surface roughness) for optimizing these surface parameters are specified. The friction mechanisms involved reveal why these features are more desirable. RESULTS: Although surface roughness is important in determining slipperiness, there is still insufficient information to establish a safety criterion based on roughness; however, the method presented in this paper can readily provide a relative comparison. IMPACT ON INDUSTRY: The summary presented will help safety professionals properly select new floor surfaces or assess existing floors to reduce slip and fall accidents.     

Objective and subjective measurements of slipperiness in fast-food restaurants in the USA and their comparison with the previous results obtained in Taiwan

Floor slipperiness is a critical issue in slip and fall incidents which are a major source of occupational injuries. The objectives of the current study were to investigate if the protocols used in a field study conducted in Taiwan could be used in similar environments in the USA and whether consistent results could be obtained. Protocols used in the field study to investigate floor slipperiness in western-style fast-food restaurants in Taiwan included both objective and subjective measurements. Using the same methods as in Taiwan, friction was measured on tiles in six major working areas of 10 fast-food kitchens in the USA as an objective measurement of slipperiness, while the subjective measurement was employees’ ratings of floor slipperiness over the same areas. The Pearson’s and Spearman’s correlation coefficients in the USA between the averaged friction coefficients and subjective ratings for all 60 evaluated areas across 10 restaurants were 0.33 (p = 0.01) and 0.36 (p = 0.005), respectively, which were lower than the correlations of 0.49 and 0.45, respectively, obtained in Taiwan. Cultural differences, the amount of water on the floors in the sink areas and the existence of a slip resistant shoe program in one country might be contributors to the lower correlation coefficients in the USA. However, the current study confirmed the results obtained in Taiwan that average friction coefficient and perception values are in fair agreement, suggesting that both might be reasonably good indicators of slipperiness.     

The Surface Roughness of a Rubber Soling Material Determines the Coefficient of Friction on Water-Lubricated Surfaces

For more than a decade, evidence has been accumulating that points to the fact that the microscopic roughness of the footwear soling surface is a major determinant of slip-resistance on lubricated surfaces, but conclusive experimental proof has been lacking. This article describes an experiment in which five pairs of shoes were soled with the same rubber compound. Four of the pairs were abraded by different grades of grit to produce a range of roughness values. The coefficient of friction (CoF) of the five solings was then measured repeatedly by the walking traction method on wet surfaces including glazed wall tiles, vinyl asbestos coated with the wax floor polish, and both sides of a sheet of float glass. The Kruskal-Wallis statistical test proved beyond doubt that the soling roughness is a major factor in determining the CoF of this rubber soling material; p < 10⁻⁵. Nearly all of the grip was due to surface roughness of the soling material on these atypically smooth floors, although the surface roughness of the floors also had a significant effect on CoF; p < 0.003. Float glass is shown to be a promising reference floor material for the measurement of CoF of footwear; there was no statistical difference between results for the two sides of the glass sheet. Float glass could be used in the development of a standard CoF test method because new sheets of glass from the same manufacturer are identical and extremely smooth. The specification of CoF values for solings/floors combinations in lubricated conditions is of little value unless associated with roughness measurements and knowledge of how wear will affect the surface roughness of the sole. This article reports the first evidence that any specification of flooring by measuring CoF based on dry surfaces could lead to an increase in the number of injuries caused by slipping on the wet surfaces. Published by Elsevier Science Ltd     

Gender in the boss–subordinate relationship: a Nigerian study

The present study examines the interaction effect of gender of both subordinates and supervisors on subordinates' perception of differentiation of boss–subordinate relationship in an African setting. Data was collected from a total of 60 boss–subordinate dyads in four‐sex combinations obtained through a survey of a large five‐star hotel in Abuja, Nigeria. Results revealed that subordinates in opposite‐sex dyads perceived better quality of exchange than those in same‐sex dyads. The strongest quality of exchange was perceived in male boss–female subordinate dyad, while the weakest was perceived in female boss–female subordinate dyad. This emphasizes the importance of gender in the differentiation of boss–subordinate relationships in an African setting. Copyright © 2004 John Wiley & Sons, Ltd.     

Human walks carefully when the ground dynamic coefficient of friction drops below 0.41

This study investigated the available and utilized friction during non-slip gait in level walking, and determined the limit which human starts to walk carefully to adapt to slippery surface. Sixteen floor–footwear-contaminant conditions with different slipperiness (dynamic coefficient of friction, DCOF, from 0.11 to 1.06) were employed. Fifteen harnessed Chinese male performed ten self-paced walking trials in each condition without slips. The utilized friction (COF_u) was obtained from the maximum value of shear to normal ground reaction force ratio during the first 25% stance. ANOVA and Tukey tests showed three subsets with similar COF_u, and confirmed the hypothesis that the utilized friction drops gradually when the available friction drops below a certain critical limit. Non-linear regression models were applied to the data to determine the COF_u to be 0.20 and the limit of available ground friction which human starts to walk carefully to adapt to slippery surface (DCOF_limit) to be 0.41.     

Users’ acceptance of private automated vehicles: A systematic review and meta-analysis

Introduction: This research systematically reviewed relevant studies on users’ acceptance of conditional (Level 3) to full (Level 5) automated vehicles when such vehicles are to be used privately (herein referred to as ‘private automated vehicles or private AVs). Method: The search followed the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, and was undertaken in three databases: APA PsycINFO, Transport Research International Documentation, and Web of Science. Articles were required to focus on individuals’ acceptance of private SAE Level 3–5 AVs. Acceptance was defined as individuals’ attitudes towards or intentions and/or willingness to use AVs in the future. A total of 2,354 articles were identified in the database search. Thirty-five articles were included in the review, six of which included multiple studies and/or comparison groups. Results: Most studies (n = 31) applied self-reported measures to assess user acceptance together with a range of psychosocial factors predicting such acceptance. The meta-analytic correlations revealed that perceived behavioral control, perceived benefits/usefulness, perceived ease of use, and subjective/social norms had significant positive pooled relationships with attitudes and intentions. Trust and sensation seeking also had significant positive pooled correlations with intentions, while knowledge of AVs had a significant and negative pooled correlation with intentions. Age did not show any significant pooled relationship with attitudes, intentions, or willingness. Conclusions: The findings obtained from the systematic review and meta-analysis provide support for psychosocial models to aid understanding of users’ acceptance of private AVs. Practical applications: Examining acceptance of AVs after participants have experienced these vehicles on closed tracks or open roads would advance contemporary knowledge of users’ intentions to use these vehicles in the future. Further, experiencing these vehicles firsthand may also help with addressing any perceived barriers reducing acceptance of future use of private AVs.     

Adolescents' perspectives on distracted driving legislation

Purpose: Distracted driving is a growing global epidemic, with adolescent drivers reporting frequent engagement in distracted driving behaviors. Public health initiatives and legislative efforts designed to decrease the prevalence of these unwanted driving behaviors have demonstrated small, but significant reductions in crash risk. Non-compliance is a known problem among drivers of all ages, but may be especially problematic for novice, adolescent drivers. Using a construct from the Health Belief Model, the relations between demographic factors, perceived threat to safety, and peer influences were investigated with adolescents' support for three types of distracted driving legislation regarding: (a) reading or sending text messages/emails while driving; (b) hand-held cell phone use while driving; and (c) using non-driving-related-in-vehicle (NDIV) technology while driving. Investigating adolescents' perceptions provides an opportunity to understand distracted driving enforcement and legislation. Methods: Three hundred and seventy-nine adolescents aged 15–19 (M = 16.12, SD = 0.56) were recruited from public high schools. Demographics, perceptions, and support regarding distracted driving were assessed using self-report surveys. Statistical analyses included bivariate correlations and adjusted odds ratios to investigate influences of adolescent support for distracted driving legislation. Results:Female adolescents were at 2 times greater odds of supporting a law against texting/emailing while driving compared to male adolescents. Greater perceived threat to safety was associated with all three types of distracted driving legislation (aOR = 1.10, 1.33). Minimal association was found with peer influences. Conclusions: Perceived threat to safety and gender were associated with legislative support in adolescents. Practical application: Interventions and public health campaigns that incorporate elements related to perceived threat may be more successful with female adolescent drivers than male adolescents. Future experimental research will help to determine what factors affect adolescents' perspectives on distracted driving to promote compliance with related legislation.     

Lower Leg Injury Reference Values and Risk Curves from Survival Analysis for Male and Female Dummies: Meta-analysis of Postmortem Human Subject Tests

Objective: Derive lower leg injury risk functions using survival analysis and determine injury reference values (IRV) applicable to human mid-size male and small-size female anthropometries by conducting a meta-analysis of experimental data from different studies under axial impact loading to the foot–ankle–leg complex.

Methods: Specimen-specific dynamic peak force, age, total body mass, and injury data were obtained from tests conducted by applying the external load to the dorsal surface of the foot of postmortem human subject (PMHS) foot–ankle–leg preparations. Calcaneus and/or tibia injuries, alone or in combination and with/without involvement of adjacent articular complexes, were included in the injury group. Injury and noninjury tests were included. Maximum axial loads recorded by a load cell attached to the proximal end of the preparation were used. Data were analyzed by treating force as the primary variable. Age was considered as the covariate. Data were censored based on the number of tests conducted on each specimen and whether it remained intact or sustained injury; that is, right, left, and interval censoring. The best fits from different distributions were based on the Akaike information criterion; mean and plus and minus 95% confidence intervals were obtained; and normalized confidence interval sizes (quality indices) were determined at 5, 10, 25, and 50% risk levels. The normalization was based on the mean curve. Using human-equivalent age as 45 years, data were normalized and risk curves were developed for the 50th and 5th percentile human size of the dummies.

Results: Out of the available 114 tests (76 fracture and 38 no injury) from 5 groups of experiments, survival analysis was carried out using 3 groups consisting of 62 tests (35 fracture and 27 no injury). Peak forces associated with 4 specific risk levels at 25, 45, and 65 years of age are given along with probability curves (mean and plus and minus 95% confidence intervals) for PMHS and normalized data applicable to male and female dummies. Quality indices increased (less tightness-of-fit) with decreasing age and risk level for all age groups and these data are given for all chosen risk levels.

Conclusions: These PMHS-based probability distributions at different ages using information from different groups of researchers constituting the largest body of data can be used as human tolerances to lower leg injury from axial loading. Decreasing quality indices (increasing index value) at lower probabilities suggest the need for additional tests. The anthropometry-specific mid-size male and small-size female mean human risk curves along with plus and minus 95% confidence intervals from survival analysis and associated IRV data can be used as a first step in studies aimed at advancing occupant safety in automotive and other environments.     

Anthropometric study of emergency medical services providers (EMSP) in the United States

Introduction: Design of next-generation ambulance patient compartment requires up-to date anthropometric data of emergency medical service providers (EMSP). Currently, no such data exist in the U.S. A large-scale anthropometric study of EMSP in the U.S. were conducted. This report provided the summary statistics (means, standard deviation, and percentiles) of the study’s results and examined the anthropometric differences between the EMSP dataset and the U.S. general population, and between the EMSP dataset and U.S. military personnel dataset, respectively. Method: An anthropometric study of 471 male and 161 female EMSP from across the continental US was conducted, using a sampling strategy that took into account age, sex, and race strata. Results: On average, male EMSP were found to be 18 mm taller and 7 kg heavier than US male general population, and 19 mm taller and 11 kg heavier than US male military personnel. Female EMSP were found to be 25 mm taller than US female general population, and 10 kg heavier than US female military personnel. Conclusions: These results showed that it would be inappropriate to apply general population or military data to the design of next-generation ambulance patient compartment. This new dataset provided the most recent and accurate EMSP anthropometric measurements available in the US. Practical Application: Data from this study provided an invaluable resource for the design of next-generation ambulances in the US.     

Lifting technique and abdominal belt usage: a biomechanical, physiological and subjective investigation

Some 10 male subjects carried out a repetitive lifting task for 15 min under four conditions on separate days. Subjects used either a squat lifting or a stoop lifting technique with or without an abdominal belt on each day. Measurements of spinal shrinkage, heart rate, perceived exertion and regional body pain were made under each condition. Although there was a significant difference in spinal shrinkage under all lifting conditions compared with shrinkage during 15 min of quiet standing (4.36 ± 2.24 vs. 1.13 ± 1.18 mm), there were no significant differences in shrinkage between the conditions. The subjects' heart rates were higher during the squat lift than the stoop lift (123 vs. 97 beats/min; p < 0.001). While the squat lift was perceived to be the safest lift by 90% of the subjects, 60% regarded this lift as the least preferred method (with or without the belt). Although all 10 subjects perceived the safest lifting method to involve the use of the belt, 50% rated the belt as their least preferred lifting condition. The findings cast doubt on the efficacy and acceptability of both abdominal belts and the practice of training workers in ‘safe’ lifting techniques and indicate that individual characteristics and preferences need to be considered when attempting to improve the safety of manual handling operations in industry.     

Perceived stress,mental health,organizational factors,and self-reported risky driving behaviors among truck drivers circulating in France

Introduction: The growth of the European market for road-freight transport has recently led to important changes. The growing number of foreign pavilion drivers transiting in France, which plays a bridging role among European countries, has influenced the lives of truck drivers by increasing competition, pressure on day-to-day activities, and constraints related to delivery deadlines. Adding this new pressure to those inherent in the road-freight transport sector has raised concerns, especially ones linked to levels of perceived stress by truck drivers. Method: With safety concerns in mind, we devised a questionnaire aimed at understanding how French truck drivers and non-French truck drivers, passing through four highway rest areas in France perceive stress, organizational factors, mental health, and risky driving behaviors. A sample of 515 truck drivers took part in the survey (260 French nationals), 97.9% of whom were male. Results: The results of a structural equation model indicated that perceived stress can increase self-reported risky driving behaviors among truck drivers. Furthermore, organizational factors and mental health were closely linked to perceived stress. Finally, some differences were found between French and non-French truck drivers with respect to mind-wandering and mental health, and to perceive driving difficulties to overcome and driving skills. Practical Applications: Several recommendations based on the findings are provided to policymakers and organizations.     

Slip safety risk analysis of surface properties using the coefficients of friction of rocks

This study was conducted to determine the most appropriate surface processing techniques (SPT), environmental conditions (EC) and surface roughness (SR) to minimize the risk of slipping when pedestrians walk on a floor covering of rocks barefoot and with shoes. Coefficients of friction (COFs) and values of SR were found using five different types of rocks, four SPT and two (ramp and pendulum) tests. Results indicate that the parameters which affect the COF values of rocks include SR, EC and SPT. Simple linear regression was performed to examine the relationship between the values of the COF and the SR. The value of the COF was identified as R²?≥?0.864. Statistical results, which are based on experimental measurements, show that rocks are classified according to their safe use areas depending on their COF and SR values.     

Factors affecting pedestrian behaviors at signalized crosswalks: An empirical study

Introduction: Safety of pedestrians depends, among other factors, on their behavior while crossing the road. This study aims to assess behaviors of pedestrians at signalized crosswalks. Method: Following a literature review and a pilot study, 25 vital pedestrian crossing factors and behaviors were determined. Then data was randomly collected for 708 pedestrians at 10 lighted crossings in Sharjah (UAE), five at road intersections and five mid-block crossings. Results: Results indicated that 17.4% of pedestrians observed crossed partly or fully on red and that crossing speed was 1.22 m/s, on the average, which is slightly faster than most speeds recorded in the literature. Moreover, female pedestrians were more likely to cross while chatting with others, less likely to cross on red, and more likely to walk slower than male pedestrians. Results also showed that pedestrians who crossed at road intersections walked slower than those who crossed at mid-block crossings. It was also found that longer red pedestrian times and narrower roads tended to encourage pedestrians to cross on red and that the majority of pedestrians did not look around before crossing. Practical implications: Use of the Health Belief Model for pedestrian safety are discussed.     

Safety analysis of slipping barefoot on marble covered wet areas

This study was conducted in order to determine the suitable surface processing techniques which will increase the safety of pedestrians, reducing the risk of slipping on wet floor coverings on which they walk barefoot. In the scope of the study, slip angle of surface-processed marbles in three different dimensions is determined by using DIN 51097 Standard “The determination of the characteristics that reduce slipping on wet, barefoot surfaces”. Slip angles were calculated with the help of an inclined plane method and by using three different surface processing techniques (polishing, honing and tumbling techniques) for five different types of marble. It was found that the parameters which affected slip angle values of the marbles were surface roughness, plate sizes, grain size of the abrasives used for surface processing, physical and mechanical properties. Statistical analysis was used to determine the relationship between these parameters. The marbles were then grouped according to safe utilization places depending on slip angle and surface roughness, according to the statistical results.     

Systematic patterns and random fluctuations in time series of coefficients of friction measured on floor surfaces

Coefficients of friction were measured periodically over a period of 30 months on the surfaces of five types of floor coverings in a new sport complex. The resulting time series were analysed with regard to both systematic and random short- and long-term effects of wear and maintenance. For detailed information about the involved wear mechanisms, two test sites characterized by different levels of pedestrian traffic were investigated for each floor covering. The systematic trends observed in time series of mean coefficients of friction were consistent with measured surface roughness parameters and could be divided into three categories, depending on the predominant wear mechanisms: smoothing of rough surfaces was accompanied by average monthly reductions of 0.007–0.014 in the coefficients of friction, measured under wet conditions, while mechanical polishing combined with coating by care products caused average changes between 0.002 and 0.006 per month. Progressive scratching and roughening of an initially smooth floor surface continuously increased the measured coefficients of friction by 0.003 per month. The cumulative long-term effects of surface wear exceeded the random variations in time series of mean coefficients of friction, characterized by a repeatability standard deviation of 0.006 and a reproducibility standard deviation of 0.020, respectively. For one specific floor covering, seasonal variations with an amplitude of 0.015 were observed in the time series of measured coefficients of friction.