Sleep-wake rhythm in an irregular shift system

Sleep in shift work has been studied extensively in regular shift systems but to a lesser degree in irregular shifts. Our main aim was to examine the sleep-wake rhythm in shift combinations ending with the night or the morning shift in two irregular shift systems. Three weeks' sleep/work shift diary data, collected from 126 randomly selected train drivers and 104 traffic controllers, were used in statistical analyses including a linear mixed model and a generalized linear model for repeated measurements. The results showed that the sleep-wake rhythm was significantly affected by the shift combinations. The main sleep period before the first night shift shortened by about 2 h when the morning shift immediately preceded the night shift as compared with the combination containing at least 36 h of free time before the night shift (reference combination). The main sleep period before the night shift was most curtailed between two night shifts, on average by 2.9 and 3.5 h among the drivers and the controllers, respectively, as compared with the reference combination. Afternoon napping increased when the morning or the day shift immediately preceded the night shift, the odds being 4.35-4.84 in comparison with the reference combination. The main sleep period before the morning shift became 0.5 h shorter when the evening shift preceded the morning shift in comparison with the sleep period after a free day. The risk for dozing off during the shift was associated only with the shift length, increasing by 17 and 35% for each working hour in the morning and the night shift, respectively. The results demonstrate advantageous and disadvantageous shift combinations in relation to sleep and make it possible to improve the ergonomy of irregular shift systems.     

高速铁路软土地基处理对策及效果分析

介绍了沪宁段铁路沿线的软土分布特征,将沿线软土地基分为4类,并从技术和经济两方面,分别对各类软土地基的处理进行了分析和比较,提出了相应的处理建议。     

青海省青藏铁路沿线鼠疫防治思考

目的通过对青藏铁路建设以来青海省境内沿线鼠疫监测资料的总结分析,科学评估这一地区鼠疫流行动态,探讨青藏铁路沿线鼠疫防治思路。方法监测点按照《青藏铁路鼠疫防治技术方案》和《青藏铁路鼠疫防控工作方案》实施监测工作,铁路沿线的国家级监测点按照《全国鼠疫监测方案》实施监测工作。汇总分析2001-2008年青藏铁路沿线青海省境内的鼠疫监测资料。结果2001-2008年监测面积达224190km^2,收集可检啮齿动物材料5822份、媒介材料2617份、动物血清4966份。分离到鼠疫菌93株,监测到阳性血清249份。结论近年来青藏铁路沿线动物间鼠疫流行活跃且呈上升趋势。青藏铁路沿线的乌兰县、天峻县是鼠疫流行较为严重的地区。怎样预防鼠疫沿青藏铁路线远距离传播,应引起相关部门的高度重视。     

略论铁路突发公共卫生事件应急处理个人防护装备基本要求

铁路突发公共卫生事件主要包括重大传染病疫情、集体性食物中毒和集体性职业中毒三种,危害因素复杂多样,个体防护装备是应急处理首选的预防性措施,在构建＂以人为本,和谐铁路＂的时代背景下,对个人防护装备的种类和性能提出更高要求。本研究分析了铁路突发公共卫生事件中的主要危害因素,提出了个人防护分级和防护装备分类原则,并对防护装备的性能选择、使用维护以及培训演练提出基本要求,以确保防护装备切实起到防护作用,充分保障应急队员的健康和安全,保证应急处理工作的顺利进行。     

战役卫勤快速支援系统铁路输送的组织

介绍了战役卫勤快速支援系统的基本情况和装载情况,并给出了其在装载中、铁路运输途中以及卸载时的注意事项,为卫勤分队实现战时应战、平时应急奠定了基础,提高了适应环境能力和自我保障能力。     

Prevalence of musculoskeletal disorders among Indian railway sahayaks

Railway sahayak or also known as coolie is one of the oldest occupations in India. This occupational group is continuously subjected to various musculoskeletal problems due to repetitive load exertion in unnatural postures. The present research aims to examine the prevalence of musculoskeletal disorders (MSDs) among Indian railway sahayaks. A cross-sectional study has been conducted on a sample of 51 male sahayaks. With a modified Nordic questionnaire, data were collected on their demographics, work, and musculoskeletal pain history. Electromyography (EMG) of the upper trapezius muscle of selected 12 healthy sahayaks having no history of neck–shoulder complaints were analyzed under different load lifting and carrying conditions. Additionally, ergonomic risk levels were recorded using Rapid Entire Body Assessment method. The questionnaire revealed that for the past 1 year prevalence, the most affected body regions of railway sahayaks were neck (47%), shoulder (51%), lower back (43%), and knee (47%). The association between age group and MSDs in different body regions were found significant (p = 0.012 for neck, p = 0.017 for shoulder, etc.). Work experience also had a significant relation to the MSDs in different body regions (p = 0.013 for shoulder,p = 0.023 for calf, etc.). Analysis of variance reveals high significance level between EMG values and tasks performed by the sahayaks. In conclusion, railway sahayaks were found to have high rate of MSDs which may be associated with lifting/carrying heavy loads in awkward postures. Ergonomic interventions must be implemented to reduce the risk level on this group of workers.     

Flexural Performance of Cement-Treated Sand Reinforced with Geogrids for Use as Sub-Bases of Pavement and Railway Structures

Cement-treated sand (CTS) exhibits undesirable brittle behavior after the applied stress reaches its peak strength. This research investigates the flexural behavior of CTS that is reinforced with uniaxial geogrid (CTSG). A total of 6% cement content was mixed with sand. Uniaxial geogrids with three different strengths were utilized to create the CTSG samples. The number of reinforcement layers, including single and double reinforcements, was studied. The image processing method was applied to analyze the surface cracks in the specimens. The results show that the geogrid type and the number of reinforcement layers affect the flexural behavior of the CTSG. Geogrid reinforcement changed the behavior of the CTS from a brittle material to a semi-brittle or ductile material because the residual tensile stresses were carried by the geogrids. The high-strength geogrid with a double reinforcement layer proved to be most effective in enhancing the peak strength and toughness with improvement ratios of 1.80 and 11.7, respectively. Single and double reinforcement layers with all geogrid types can reduce surface cracks with average crack reduction ratios of 64% and 83%, respectively. The CTSG can be successfully used as a sub-base layer to increase flexural performance and the lifetime of pavement and railway structures.     

太原市城区铁路边界噪声污染状况调查

[目的]了解太原市城区范围内铁路边界噪声的污染状况。[方法]按照GB 12525-90《铁路边界噪声限值及其测量方法》对城区和铁路边界进行噪声监测。[结果]噪声敏感点以铁路住宅区为主,这些住宅区均与铁路边界重合;列车在各敏感点区段均须鸣笛,未采取噪声控制措施;各监测点的昼、夜间噪声值,作为铁路边界噪声合标率达90.91%,作为环境噪声其合标率为0%。[结论]太原市城区范围内铁路边界噪声作为噪声源合标率很高,但对与铁路边界重合的敏感点的环境噪声污染很严重。     

Cancer incidence among male railway engine-drivers and conductors in Sweden, 1976–90

During recent years, the relationship between exposure to magnetic fields and cancer has attracted increasing interest. In Sweden, train personnel are exposed to comparatively strong magnetic fields in their work. The aim of the present study was to investigate cancer incidence, particularly leukemia and brain tumors, among male railway engine drivers and conductors, respectively, and to compare their cancer incidence with that of the general male population. The study population comprised all male railway engine drivers (n=7,466) and conductors (n=2,272) who were ever employed at the Swedish State Railways during the period 1976–90. The study population was observed with regard to cancer incidence by means of the National Cancer Register for the period 1976–90. The total cancer incidence (all tumors included) among railway engine drivers was lower than in the general Swedish population. An increased incidence of lymphocytic leukemia was observed among railway engine drivers and conductors combined (relative risk = 2.3; 95 percent confidence interval = 1.3–3.2), with the same point estimate for both occupational groups. For brain tumor (astrocytoma), the observed relative risk was close to one. The study provides evidence of an excess risk of lymphocytic leukemia in railway engine drivers and conductors, workers with known occupational exposure to magnetic fields.Drs Alfredsson and Hammar are with the Division of Epidemiology, Institute of Environmental Medicine, Karolinska Instituter, Stockholm, Sweden. Dr Alfredsson is also with the Department of Occupational Health, Karolinska Hospital, Stockholm, Sweden. Dr Karlehagen is with the National Occupational Health Services, Örebro, Sweden. Address correspondence to Dr Alfredsson, Division of Epidemiology, Institute of Environmental Medicine, Karolinska Institutet, Box 210, S-171 77 Stockholm, Sweden. The study was supported by the Swedish State Railway Company.