Influence of an oblique path of staircase descent on toe placement and foot clearance

During their commute, pedestrians encounter a variety of staircase designs. One such design is the oblique staircase that allows pedestrians to descend at an angle. The purpose of this study was to assess the influence of an oblique path of descent on heel and toe clearance, and toe placement on a step. Sixteen participants descended a staircase on an angled path at three angles: 0° (perpendicular), 25°, and 45°. Toe placement and foot clearances were compared between the descent angles and feet. An increase in descent angle demonstrated increased clearance of the heel apex compared with straight descent; however, the aspect of the foot closest to the stair changes in angled descent, moving from the apex to the side of the heel. A greater portion of the foot was placed on the stair tread during angled descent. Future work should address the influence of angled descent on fall risk.     

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.     

Slip Resistance of Industrial Floor Surfaces: Development of an Elastomer Suited to In-Situ Measurement

Slips contribute to 12% of occupational accidents. A slip resistant floor is a mean to prevent slipping accidents occurring in workshops. Floor slip resistance is often evaluated by measuring a friction index, proportional to the force opposing slipping of a reference elastomer on the floor surface under test. When implementing a portable appliance, slip resistance measurements carried out on lubricated floors were not stabilized. The authors advanced the hypothesis of oil impregnating the elastomer. A new elastomer suited to in-situ measurement has been developed to achieve stable measuring conditions. This study highlights the fact that the nature and characteristics of a reference elastomer must be specified when slip resistance measurements are carried out.     

Reaction Moment at the L5/S1 Joint During Simulated Forward Slipping With a Handheld Load

The purpose of the study was to investigate the effects of load on the net moment response at the L5/S1 joint during simulated slip events. Six young individuals were instructed to take one step with a handheld load. Sudden floor movement was randomly introduced to simulate unexpected slips. Different loads conditions (0%, 10%, 20%, 30% of body weight) were introduced at random. Three-dimensional net moments at the L5/S1 joint were computed via downward inverse dynamic model. Peak joint moment generated at 30% load level was found to be significantly higher compared to no-load condition. No peak moment differences were found among no-load, 10% or 20% load levels. Additionally, the findings from this study indicated a flexiondominant net L5/S1 joint moment pattern during motion phase associated with slip-induced falls.     

Slipping on pedestrian surfaces: methods for measuring and evaluating the slip resistance

Tripping, slipping and falling accidents are among the types of accident with a high incidence. This article describes the requirements concerning slip resistance, as well as the state of the art of slip resistance measurement standards in the European Community and the USA. The article also describes how risk assessment can be performed in the field.     

Performance of slippery and slip-resistant footwear in different wintry weather conditions measured in situ

In Finland about 70,000 people are annually injured in pedestrian and bicycle falling accidents occurred at the street, walkways and courtyards. Around 2/3 of these occur when the walking surface is covered by ice or snow. In general, slipping is caused by both environmental and human factors. The primary environmental factor behind slipping accidents is slip resistance characteristics of underfoot surface. Especially in winter slipping accidents are mainly due to inadequate friction between footwear and underfoot surfaces. Portable devices measuring friction, i.e. slipmeters, may be used for assessing slipperiness on different walking surfaces in situ. During winter seasons 2003 and 2004 a study was performed to evaluate the usability of portable slip simulator for measuring slipperiness of walkways on varying weather conditions and to assess slip resistance of different footwear. The Portable Slip Simulator proved to be applicable for measuring in situ the slipperiness of wintry walking surfaces and evaluating quality of winter maintenance. Significant differences in traction between footwear were found especially in normal Finnish climate winter days when friction provided by slip-resistant footwear was multifold compared to a poorer one. On very slippery icy surfaces no footwear provided enough grip and, therefore, in such conditions anti-slip devices should be used.     

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.     

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.     

Slips and falls on ice and snow in relation to experience in winter climate and winter sport

The objective of this paper was to investigate whether living experience in winter climate and winter sport helps to prevent slips and falls on ice and snow. A questionnaire survey was conducted among foreigners at Luleå University of Technology of Sweden, where winter season lasts for six months in a year. Seventy respondents replied. The results of ordinal regression showed that the slip frequency according to a 5-point rating scale decreased as the living experience in cold environments increased (B=−0.0113, p=0.019). A logistic regression was applied to model the probability of fall events occurrence based on the experience of living in cold climate. The results showed that the fall events reduced as living experience increased (B=−0.030, p=0.001). Chi-square test showed that fall events in those who took part in winter sport were significantly less than in those who did not participate in winter sport (χ²=10.745, p=0.001). The findings imply that experience of living in cold environments and training in gait balance on ice and snow can have positive effects in preventing slips and falls for inexperienced workers and pedestrians. This study also revealed that the majority of fall events happened on hard ice covered with snow while wearing ordinary winter footwear, indicating the need to improve slip resistance.     

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.     

Floor slip resistance changes in food sector workshops: prevailing role played by “fouling”

Over 10% of occupational accidents are triggered by a slip. These accidents are more frequent in food sector workshops. Anti-slip floors are a means of preventing slips. Much has been done in terms of methodology to assess slip resistance and measurement of new floor slip resistance. To date, no study has dealt with time-related changes in slip resistance in the field. Floor roughness is the first criterion which comes to mind when explaining floor slip resistance values or changes. This study, conducted in four food sector enterprises, points out the possible role played by another factor: “fouling” of the industrial floor over a period of several months after it has been finished. Similar slip resistance changes have been observed in several workshops, namely, a major decrease right from the first days of activity followed by stabilization over the following months. Changes in floor roughness cannot explain the recorded variation in slip resistance, which possibly results from fouling of the floor finishing.     

Effects of Diabetic Neuropathy on Body Sway and Slip Perturbation Detection in Older Population

Postural control is a common mechanism to compensate for unexpected displacements of the body. In the older population, a slip or fall due to a failure of postural control is a common cause of morbidity and mortality. The ability of postural control decreases with aging or neuropathy. In this study, 2 groups, diabetics and non-diabetics in the older population, were compared to determine how patterns of postural sway during quiet standing were related to the detection of perturbation. The SLIP-FALLS system was applied to the measurement of sway and detection of perturbation. In phase 1 of the development of the predictive model, neural network algorithms were applied to find determinant variables for perturbation detection. In phase 2, a fuzzy logic inference system was developed to investigate the relationship between sway and perturbation detection. Results of this study may be applied to the design of floor mats or shoe insoles for preventing fatigue in workplaces.     

Effects of diabetic neuropathy on body sway and slip perturbation detection in older population.

Postural control is a common mechanism to compensate for unexpected displacements of the body. In the older population, a slip or fall due to a failure of postural control is a common cause of morbidity and mortality. The ability of postural control decreases with aging or neuropathy. In this study, 2 groups, diabetics and non-diabetics in the older population, were compared to determine how patterns of postural sway during quiet standing were related to the detection of perturbation. The SLIP-FALLS system was applied to the measurement of sway and detection of perturbation. In phase 1 of the development of the predictive model, neural network algorithms were applied to find determinant variables for perturbation detection. In phase 2, a fuzzy logic inference system was developed to investigate the relationship between sway and perturbation detection. Results of this study may be applied to the design of floor mats or shoe insoles for preventing fatigue in workplaces.     

高填路堤边坡失稳机理与处治措施分析

高填路堤稳定性已成为制约山区高速公路建设的重要因素。以某失稳高填路堤为工程背景,基于将填方路堤和原 始地基作为整体边坡考虑的基本思路,根据现场调查、勘察成果,构建典型地质剖面模型,通过极限平衡条分法,对边 坡稳定性的影响因素,如水位、岩土体重度、内聚力、摩擦角等进行敏感性分析,计算得到边坡潜在滑动面剪出口与现 场实际基本一致,并分析其失稳是在持续强降雨入渗、填方路基土强度弱化后,在填筑路堤、粉质粘土夹碎石层与基岩 交界面顺层滑动剪出;最后分析不同抗滑桩设置位置、强度、间距支护作用下边坡安全系数及潜在滑面情况,推荐在距 离坡脚5 m处设置抗滑桩且其每米间距强度应大于250 t的处治方案。     

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.     

一维脉冲波透过压电介质摩擦接触界面的传播

以压电材料为核心的结构和元件在装置中,总是和其他材料组合在一起,常用来传导表面波或承受动荷载,界面是其中的重要组成部分。当扰动很强时,会引起接触界面的局部滑移和分离,对结构安全产生威胁。笔者对一维脉冲波透过横观各向同性压电介质摩擦接触界面的传播进行了研究。利用Fourier分析的方法,将混合边值问题化为非线性代数方程组,通过迭代修正,确定了界面上分离、滑移和粘着3种区域的分布范围,同时计算了界面剪力和相对滑移速度的分布。笔者进一步丰富了压电弹性波动理论,利用波所携带的力学或电学信息,可望无损探测界面的接触状态及接触力等参量,对结构的安全评估与寿命预测具有重要的理论价值与实际意义。     

Slip resistance and the UK Slip Resistance Research Group

Kime, G.A., 1991. Slip resistance and the UK Slip Resistance Research Group. Safety Science, 14: 213–219.This paper highlights some of the problems concerned with slipping accidents and gives the history of the UK Slip Resistance Group and the use of dynamic mechanical thermal analysis (DMTA) to characterise the various slidder rubbers. Discussion concerning the theory of slipping and the influences other than the coefficient of friction that make up slip resistance, and the clarification of the parameters for a safe floor surface are presented.     

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.     

Exposure to fall hazards and safety climate in the aircraft maintenance industry

PROBLEM: Falls represent a significant occupational hazard, particularly in industries with dynamic work environments. This paper describes rates of noncompliance with fall hazard prevention requirements, perceived safety climate and worker knowledge and beliefs, and the association between fall exposure and safety climate measures in commercial aircraft maintenance activities. METHODS: Walkthrough observations were conducted on aircraft mechanics at two participating facilities (Sites A and B) to ascertain the degree of noncompliance. Mechanics at each site completed questionnaires concerning fall hazard knowledge, personal safety beliefs, and safety climate. Questionnaire results were summarized into safety climate and belief scores by workgroup and site. Noncompliance rates observed during walkthroughs were compared to the climate-belief scores, and were expected to be inversely associated. RESULTS: Important differences were seen in fall safety performance between the sites. The study provided a characterization of aircraft maintenance fall hazards, and also demonstrated the effectiveness of an objective hazard assessment methodology. Noncompliance varied by height, equipment used, location of work on the aircraft, shift, and by safety system. DISCUSSION: Although the expected relationship between safety climate and noncompliance was seen for site-average climate scores, workgroups with higher safety climate scores had greater observed noncompliance within Site A. Overall, use of engineered safety systems had a significant impact on working safely, while safety beliefs and climate also contributed, though inconsistently. IMPACT ON INDUSTRY: The results of this study indicate that safety systems are very important in reducing noncompliance with fall protection requirements in aircraft maintenance facilities. Site-level fall safety compliance was found to be related to safety climate, although an unexpected relationship between compliance and safety climate was seen at the workgroup level within site. Finally, observed fall safety compliance was found to differ from self-reported compliance.     

Comparing two methods of data collection for walkway friction measurements with a portable slip meter and a force platform

The objective was to investigate how two distinct data collection procedures, raw coefficient of friction (COF) data versus averaged COF data, may affect the outcome and interpretation of statistical analysis of friction tests and thus the reliability of slip resistance assessments. A prototype portable slip meter (PSM) and a force platform (FP) were used for evaluating floor friction transients over contaminated surfaces. A one-way ANOVA was performed to estimate significant differences between the PSM and the FP using raw COF data (55 measurement points) and averaged COF data (five measurement points) respectively. For comparing the FP with the portable slip meter, the best approach is to use averaged friction data. When the portable slip meter is used independently for walkway friction measurement, either the averaged or the raw data can be used to present the test results. However, the larger sample size is always the preferred choice.