Slip initiation in alternative and slip-resistant footwear

Slips occur as a result of failure of normal locomotion. The purpose of this study is to analyze the impact of alternative footwear (Crocs?, flip-flops) and an industry standard low-top slip-resistant shoe (SRS) under multiple gait trials (normal dry, unexpected slip, alert slip and expected slip) on lower extremity joint kinematics, kinetics and muscle activity. Eighteen healthy male participants (age: 22.28?±?2.2 years; height: 177.66?±?6.9?cm; mass: 79.27?±?7.6?kg) completed the study. Kinematic, kinetic and muscle activity variables were analyzed using a 3(footwear)?×?4(gait trials) repeated-measures analysis of variance at p?=?0.05. Greater plantar flexion angles, lower ground reaction forces and greater muscle activity were seen on slip trials with the alternative footwear. During slip events, SRS closely resembled normal dry biomechanics, suggesting it to be a safer footwear choice compared with alternative footwear.     

Friction measurements on “anti-slip” floors under shoe sole,contamination, and inclination conditions

Friction measurements were conducted to study the effects of shoe sole, floor, contamination, and inclined angle of the floor surface on friction coefficient. The shoe sole samples included composite rubber outsole samples with and without V-shaped tread design. Unglazed ceramic tiles of both flat and tiles with molded profile design were tested. The contamination conditions included dry, wet, and glycerol-contaminated conditions. The inclined angles included 0°, 5°, and 10°. A Brungraber Mark II slipmeter was used. The results showed that all the four factors affected friction coefficient significantly (p < 0.0001). Flat rubber soles had higher friction coefficients than the soling samples with V-shaped tread design on all tested floors and inclined angles under wet conditions. Flat soles, however, had extremely low friction when tested on flat floors under glycerol-contaminated conditions. The floors with molded grooves perpendicular to friction measurement direction had the highest friction coefficients than all other floor conditions under both the wet and glycerol-contaminated conditions except the wet/flat sole/10° condition. A regression model with a cosine function was established to describe the relationship between friction coefficient and inclined angle of the floor under the experimental conditions. This model is statistically significant at p < 0.0001 with an R² of 0.97.     

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     

Coefficient of friction,walking speed and cadence on slippery and dry surfaces: shoes with different groove depths

Objective. The present study aimed to determine the coefficient of friction (COF), walking speed (WS) and cadence while walking on slippery and dry surfaces using shoes with different sole groove depths to predict likelihood of fall. Background. Design of shoe sole groove is crucial to prevent slipping during walking. Methods. 22 healthy young men (mean age 24.5, body mass index 22.5) volunteered for this semi-experimental study. Six different conditions of the test (combination of three shoes and two surfaces) were defined and the condition was repeated three times. In total, 396 trials (22 subjects?×?3 groove depths?×?2 surfaces?×?3 times) were obtained for data analysis. COF was recorded by force platform at 1000?Hz and walking parameters recorded using 3D motion analysis with six infrared cameras at 200?Hz. Results. The highest COF was obtained from the deepest groove depth (5.0?mm) on both dry and slippery surfaces. The COF on slippery surfaces was significantly lower in comparison with dry surfaces. WS and cadence were not significantly different on dry and slippery surfaces. Conclusion. The deeper groove is better to prevent slipping because the COF increases by increasing the shoe sole groove depth. WS did not change on dry and slippery surfaces.     

Evaluation of two models of a slipmeter

The aim of the study was to compare the performances of the Brungraber Mark II (BM II) and Mark III (BM III) slipmeters. Friction measurements with the two slipmeters were conducted in a laboratory using four footwear materials, four floor types, and three surface conditions. Both the coefficient of friction (COF) values obtained with the slipmeters and the force platform-based COF values were measured. The COF measured with the BM II was slightly higher than that measured with the BM III with a R² of 0.83. A comparison of the averaged normal force between the two slipmeters showed that the BM II generated a significantly higher normal force than the BM III at a low COF and the difference of the normal force between the two slipmeters decreased when the COF value was increased. The regression analysis results in this study showed that the force platform-based COF values were closer to the COF values obtained with the BM III than with the BM II. The R² values for the regression model between the COF values obtained from the slipmeter and the force platform were 0.90 and 0.79 for the BM II and BM III, respectively.     

Effects of load carriage and work boots on lower limb kinematics of industrial workers

Load and footwear condition are two crucial elements varying the kinematic responses during walking, which probably lead to chronic injury. Fifteen healthy male individuals with no obvious gait abnormalities participated in this study. Apart from a no-load condition, four external load conditions with two load levels were investigated. Work boots were compared with running shoes to determine footwear effects. Significant impacts were found for lower limb range of motion at certain joints when carrying loads. A greater hip and ankle flexion–extension while wearing the work boots indicated that participants needed to lift the leg higher to complete toe clearance off the walking surface. Work boots also increased the vertical excursion of the center of body mass, which may impact body balance and induce falling. No significant influencing pattern of carrying modes was found, which was probably due to the light load and relatively stable mode of shoulder carrying.     

曳引轮绳槽磨损检测及预防措施

本文首先分析了曳引轮绳槽的结构型式对曳引轮绳槽的磨损影响,分别从设计制造阶段、安装调试阶段、日常使用与维护保养阶段三个阶段分析了导致绳槽磨损的原因。接着给出了检查曳引绳的磨损状况、检查曳引轮绳槽的磨损状况和曳引能力的试验三种检测绳槽磨损的方法。最后针对磨损原因的三个阶段分别提出了具体的预防措施。     

Modeling the effects of production pressure on safety performance in construction projects using system dynamics

Introduction: Construction incidents occur due to system failures, not due to a single factor such as unsafe behavior or condition. Therefore, construction safety should be investigated using a systematic view capable of illustrating the complex nature of incidents. Construction projects are also often behind their planned schedule and suffer from various pressures caused by contractual deadlines or clients. Previous studies demonstrated that such pressures negatively affect safety performance; however, the process of how production pressure influences safety performance is not fully investigated. Method: The present research aimed to understand the feedback mechanism of how production pressure interactively affects safety performance and safety-related managerial components in a construction project. Ground theory method (GTM) is used to create a conceptual causal loop diagram that shows the relationship between incident rate and other variables such as labor hour, actual and planned progress, safety climate, rework, and safety training. Moreover, a power plant construction project was used as a case study to practically investigate the conceptual model; a case study is employed to build a System Dynamics (SD) model. The simulation model was then validated using behavior reproduction and sensitivity analysis. Results: The results of the inequality statistics show that the simulation model can be used to forecast trends in the incident rate.     

Investigation and identification of factors affecting migrating peasant workers’ usage of safety footwear in the Chinese construction industry

A sample of 300 migrating peasant workers from 15 Chinese building construction sites completed a demographic questionnaire to investigate the usage of safety footwear. The survey form was constructed based on the theory of planned behaviour, and a total of 12 questions focusing on the workers’ past experience, attitudes, subjective norms and perceived behavioural control were included in the survey. It was found that 92% of the participants did not wear safety footwear while working on construction sites, although more than 91% of them believed that safety footwear would protect the foot from injury; none of the participants had been provided free safety footwear by their employer. Regression analysis shows that employers’ attitude is the most important factor affecting their usage of safety footwear, ‘providing free safety footwear’ and ‘comfortability of the safety footwear’ ranking second and third respectively.     

Friction measurements on ramps using the Brungraber Mark II slipmeter

It is a common belief that a person is more likely to slip when walking on an inclined surface than when walking on a level surface. Reports of friction measurements were common on horizontal surfaces but were rare on inclined surfaces. A slip measurement device reports different readings on the same surface with different inclined angles if the effect of gravity comes into play. In this study, friction measurements were conducted on the same surface with 0°, 10° and 20° inclined angles under different footwear materials, floors, and surface conditions, using a Brungraber Mark II slipmeter. Statistically significant results were obtained for the measurement results under the inclined angle, footwear material, floor, and surface conditions. A regression model was established to describe the coefficients of friction on ramp floors under footwear material/floor/surface conditions. This model is significant at p < 0.0001 with an R² of 0.87. The cosine function of ramp angle, as suggested in the regression model, was recommended to be used as a correcting factor for friction measurement results using the Brungraber Mark II on ramps to report the corrected friction coefficient of the surfaces.     

Evaluating sleep deprivation and time-of-day influences on crash avoidance maneuvers of young motorcyclists using a dynamic simulator

Introduction: Motorcyclists are particularly at risk of being injured when involved in a road traffic accident. To avoid such crashes, emergency braking and/or swerving maneuvers are frequently performed. The recent development of dynamic motorcycle simulators may allow to study the influences of various disturbance factors such as sleep deprivation (SD) and time-of-day (TOD) in safe conditions. Methods: Twelve young healthy males took part in 8 tests sessions at 06:00 h, 10:00 h, 14:00 h, 18:00 h after a night with or without sleep, in a random order. Participants had to perform an emergency braking and a swerving maneuver, both realized at 20 and 40 kph on a motorcycle dynamic simulator. For each task, the total distance/time necessary to perform the maneuver was recorded. Additional analysis was conducted on reaction and execution distance/time (considered as explanatory variables). Results: Both crash avoidance maneuvers (emergency braking and swerving) were affected by increased speed, resulting in longer time and distance at 40 kph than at 20 kph. Emergency braking was mainly influenced by sleep deprivation, which significantly increased the total distance necessary to stop at 40 kph (+1.57 m; + 20%; p < 0.01). These impaired performances can be linked to an increase in reaction time (+21%; p < 0.01). Considering the swerving maneuver, TOD and SD influences remained limited. TOD only influenced the reaction time/distance measured at 40 kph with poorer performance in the early morning (+30% at 06:00 h vs 18:00 h; p < 0.05). Discussion: Our results confirm that crash avoidance capabilities of young motorcyclists were influenced by the lack of sleep, mainly because of increased reaction times. More complex tasks (swerving maneuver) remained mostly unchanged in this paradigm. Practical Applications: Prevention campaigns should focus on the dangers of motorcycling while sleepy. Motorcycling simulators can be used to sensitize safely with sleep deprivation and time-of-day influences.     

Development of an objective determination of a slip with a portable inclineable articulated strut slip tester (PIAST)

A portable inclineable articulated strut slip tester (PIAST) is a slipmeter that is widely used in the USA to measure coefficient of friction (COF) at the shoe sole and floor interface. A determination of a slip at the measurement interface, which is currently judged subjectively by operators, plays a crucial role in deciding the outcomes of a PIAST measurement. The goal of this study was to develop an objective determination of a slip based on the movement of the weight used by the slipmeter. The displacement of the weight and the time duration of consecutive strikes in a measurement were used to derive the objective slip criterion. Various footwear materials, floor materials and surface conditions were used to cover a wide range of COF values. The results of the regression analysis indicated that the objective COF predicted by the method developed in the current study was significant (R² = 0.997, β = 0.991, p < 0.001) in predicting the subjective COF determined by the operator.     

超音速虹吸式空气雾化喷嘴雾化影响因素实验研究*

为掌握超音速虹吸式空气雾化喷嘴雾化机理及特性,采用流体力学线性不稳定理论分析雾化机理,通过喷雾实验研究不同因素对雾化性能的影响及对比不同类型喷嘴的雾化效果。研究结果表明:随着距喷嘴出口距离增加,超音速虹吸式空气雾化喷嘴在雾滴破碎后碰撞聚合作用由强到弱,300 mm内雾滴粒径增长速率明显,300 mm外雾滴粒径增长速率较缓。随着供气压力增加,超音速虹吸式空气雾化喷嘴雾滴粒径逐渐减小,在实测距离内SMD（平均粒径）最小为17.5 μm。不同供气压力下,超音速虹吸式空气雾化喷嘴随距离增加,雾滴粒径增长趋势基本一致。有效射程内供气压力为0.1~0.5 MPa时,SMD仅为17.5~31.16 μm。对比实验中,超音速虹吸式空气雾化喷嘴SMD比内混式空气雾化喷嘴和X旋流型压力喷嘴小53.5%~74.0%。     

Boating-related drowning in Australia: Epidemiology,risk factors and the regulatory environment

Objective: Recreational boating is a popular pastime in many high income countries, and is a leading activity prior to drowning. This study reports on unintentional fatal drowning associated with boating-related incidents in Australia. Methods: A total population, retrospective, cross sectional design examined all boating-related unintentional drowning deaths between July 1, 2005 and June 30, 2015. Variables examined included age, sex, location of drowning incident, vessel type, activity, presence of alcohol/drugs, and lifejacket wear. Relative risk (with a 95% confidence interval) was calculated using fatal drowning rates per 100,000 population and rates per 100,000 registered vessels. Chi square analysis and non-parametric tests for significance were applied. Statistical significance was deemed p < .05. Results: A total of 415 people drowned while boating during the study period, 91.8% male and 35.7% aged between 25 and 44 years. Men were 10 times more likely to drown when boating than females (RR = 10.64 CI:7.55–14.97). Over one-quarter (28.7%) of incidents involved alcohol, in 30.6% drugs were identified (31.3% were illegal) and 90.4% were not wearing a lifejacket. Children were more at risk of drowning on a houseboat than adults (RR = 7.13; CI:1.61–31.61). Females were more likely to drown than males when using a personal watercraft (RR = 10.53; CI:2.75–40.33). Conclusion: Boaters may be taking unnecessary risks by disregarding safety regulations, such as not wearing lifejackets and substance use (such as alcohol and illegal drugs). Boating in remote locations presents a high risk of drowning. While safety regulations are in place, enforcement and behavior change remain challenges. Practical application: Findings support recommendations for increased enforcement of alcohol-related regulations and introducing drug-testing for boaters. Consistency of boating safety regulations, especially around lifejacket wear, is recommended to influence behavior change. The effectiveness of current lifejacket regulations need to be critically evaluated in the context of increasing wear rates for adults and children.     

Development of new footwear sole surface pattern for prevention of slip-related falls

In this study, a new rubber surface pattern for a footwear sole was developed to prevent slip-related falls. This pattern shows a high static coefficient of friction (SCOF) and a high dynamic coefficient of friction (DCOF) when sliding against a liquid contaminated surface. A hybrid rubber block, in which a rubber block with a rough surface (Ra = 30.4 μm) was sandwiched between two rubber blocks with smooth surfaces (Ra = 0.98 μm), was prepared. The ratio of the rough surface area to the whole rubber block surface area r was 0%, 30%, 50%, 80%, and 100%. The coefficient of friction of the rubber blocks was measured when sliding against a stainless steel plate with Ra of 0.09 μm contaminated with a 90% aqueous solution of glycerol. While the SCOF increased with an increase of the rough surface area ratio r, the DCOF during steady-state sliding decreased with an increase of the rough surface area ratio r. The rough surface area ratio of 50% achieved a SCOF value around 0.5 or more and a DCOF value greater than 0.5. Furthermore, the difference in the value of the SCOF and DCOF was the smallest for the rubber block with r of 50%. The results indicated that the rubber block with r of 50% would be applicable to a footwear sole surface pattern to prevent slip and fall accidents on contaminated surfaces.     

The association between subcontractor safety management programs and worker perceived safety climate in commercial construction projects

Problem: Safety management programs (SMPs) are designed to mitigate risk of workplace injuries and create a safe working climate. The purpose of this project was to evaluate the relationship between contractors’ SMPs and workers’ perceived safety climate and safety behaviors among small and medium-sized construction subcontractors. Methods: Subcontractor SMP scores on 18 organizational and project-level safety items were coded from subcontractors’ written safety programs and interviews. Workers completed surveys to report perceptions of their contractor’s safety climate and the safety behaviors of coworkers, crews, and themselves. The associations between SMP scores and safety climate and behavior scales were examined using Spearman correlation and hierarchical linear regression models (HLM). Results: Among 78 subcontractors working on large commercial construction projects, we found striking differences in SMP scores between small, medium, and large subcontractors (p < 0.001), related to a number of specific safety management practices. We observed only weak relationships between SMP scales and safety climate scores reported by 746 workers of these subcontractors (β = 0.09, p = 0.04 by HLM). We saw no differences in worker reported safety climate and safety behaviors by contractor size. Discussion: SMP only weakly predicted safety climate scales of subcontractors, yet there were large differences in the quality and content of SMPs by size of employers. Summary: Future work should determine the best way to measure safety performance of construction companies and determine the factors that can lead to improved safety performance of construction firms. Practical applications: Our simple assessment of common elements of safety management programs used document review and interviews with knowledgeable representatives. These methods identified specific safety management practices that differed between large and small employers. In order to improve construction safety, it is important to understand how best to measure safety performance in construction companies to gain knowledge for creating safer work environments.     

Association between driver and child passenger restraint: Analysis of community-based observational survey data from 2005 to 2019

Introduction: Crash data suggest an association between driver seatbelt use and child passenger restraint. However, community-based restraint use is largely unknown. We examined the association between driver seatbelt use and child restraint using data from a state-wide observational study. Methods: Data from Iowa Child Passenger Restraint Survey, a representative state-wide survey of adult seat belt use and child passenger safety, were analyzed. A total of 44,996 child passengers age 0–17 years were observed from 2005 to 2019. Information about driver seatbelt use and child restraint was directly observed by surveyors and driver age was reported. Logistic regression was used to examine the association between driver seatbelt use and child restraint adjusting for vehicle type, community size, child seating position, child passenger age, and year. Results: Over the 15-year study period, 4,114 (9.1%) drivers were unbelted, 3,692 (8.2%) children were completely unrestrained, and another 1,601 (3.6%) children were improperly restrained (analyzed as unrestrained). About half of unbelted drivers had their child passengers unrestrained (51.8%), while nearly all belted drivers had their child passengers properly restrained (92.3%). Compared with belted drivers, unbelted drivers had an 11-fold increased odds of driving an unrestrained child passenger (OR = 11.19, 95%CI = 10.36, 12.09). The association between driver seatbelt use and child restraint was much stronger among teenage drivers. Unbelted teenage drivers were 33-fold more likely (OR = 33.34, 95%CI = 21.11, 52.64) to have an unrestrained child passenger. Conclusion: These data suggest that efforts to increase driver seatbelt use may also have the added benefit of increasing child restraint use. Practical applications: Enforcement of child passenger laws and existing education programs for new drivers could be leveraged to increase awareness of the benefits of seatbelt use for both drivers themselves and their occupants. Interventions aimed at rural parents could emphasize the importance of child safety restraints.     

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.     

Human resource management practices and organizational injury rates

Introduction: This study investigated the extent to which five human resource management (HRM) practices—systematic selection, extensive training, performance appraisal, high relative compensation, and empowerment—simultaneously predicted later organizational-level injury rates. Methods: Specifically, the association between these HRM practices (assessed via on-site audits by independent observers) with organizational injury rates collected by a national regulatory agency one and two years later were modeled. Results: Results from 49 single-site UK organizations indicated that, after controlling for industry-level risk, organization size, and the other four HRM practices, only empowerment predicted lower subsequent organizational-level injury rates. Practical Applications: Findings from the current study have important implications for the design of HRM systems and for organizational-level policies and practices associated with better employee safety.     

Access to trauma centers for road crashes in the United States

Introduction: Existing research indicates that around 90% of all U.S. residents have access to at least one level I or II trauma center within 60 min. However, a limitation of these estimates lies in that they are based on where people live and not where people are injured, which may overestimate the access to trauma centers for seriously injured patients in fatal crashes. Method: In this study, the Fatality Analysis Reporting System (FARS) data between 2013 and 2014 were collected and analyzed to quantify the access of injured patients to trauma centers for fatal crashes across states. Two types of distance, linear distance and route distance, were calculated using ArcGIS. The estimated transport time to the nearest level I/II trauma center was also calculated and compared to the recorded on-scene and transport time. Results and Conclusions: The Northeast region had the nearest average linear and route distance between fatal crash and trauma center (25.3 km and 31.7 km, respectively), followed by the Midwest (44.4 km and 54.1 km), the South (47.3 km and 57.0 km), and the West (50.9 km and 67.5 km). The comparison between the estimated and actual transport time revealed that the different states adopted different trauma triage protocols, resulting in different utilization rates of the level I/II trauma center among states. A linear regression analysis demonstrated that the longer the average route distance, the less the seriously injured patients in fatal crashes were taken to level I/II trauma center directly. Practical applications: These findings may help to identify the access to trauma centers for road crashes and the variation of delivery ratio to trauma center among the states, therefore a better utilization of trauma centers for road crashes can be achieved for the emergency medical services (EMS) systems.