The economic effects of facilitating the flow of rural workers to urban employment in China

Using a dynamic computable general equilibrium model of the Chinese economy we investigate the economic effects of relaxing China's household registration system over the period 2008 to 2020. The modelling results show that reducing the institutional restriction to rural labour movement will encourage rural workers to move from agricultural and rural non‐agricultural sectors into urban sectors. This enhanced labour movement will not only increase China's GDP and real consumption of households but it will also raise the real wages of agricultural and rural non‐agricultural workers. Although the real wage of rural migrant workers will increase at a slightly lower rate than in the baseline scenario, rural migrant workers remain considerably better paid than agricultural and rural non‐agricultural workers.     

A test of union power in the construction industry

Conclusions The tentative answers reached to the questions posed in the introduction to this paper are as follows: The relative level of union wage scales in a particular city are related to the degree of unionization of the state in which the city is located, the level of wages in manufacturing in the particular city, city size, and whether located in the South. The percentage change in journeymen's wages between 1965 and 1968 was related to the degree of unionization, to location in the highly industrialized Northcentral region, and to the percentage change in contract construction employment. The unemployment rate in the area and changes in the areas' unemployment rate were not statistically related to construction wage changes.The latter finding can be interpreted in two ways: The unemployment variable pertained to all unemployed workers in the area, rather than to unemployed construction workers, and it may be that a more refined measure of unemployment would show the expected relationship. This seems most plausible as an explanation for the lack of association with changes in journeymen's wages, but less plsusible in the case of helpers and laborers' wages. An alternative interpretation is that among the more important factors influencing construction wages in the recent past have been demand factors and factors associated with the strength of trade unions in collective bargaining, rather than pronounced shortages of labor. The latter interpretation seems to be consistent with casual empiricism and with the commonly held view that the trade unions are indeed very powerful and that, within limits, they are able to gain large settlements even when there are substantial unemployed resources.The author is indebted to Lawrence V. Asch for assisting in data collection and tabulation.     

Production arrangements by US building and non‐building contractors: an update

The paper presents the results of the first phase of a long‐term study that addresses the determinants of the production arrangements by US building (commercial and residential construction) and non‐building contractors (transportation, environmental and industrial construction). Empirical and census data are used to understand the subcontracting and self‐performance practice of the considered contractors. The significant differences in their production arrangements are explained in terms of range of technological requirements and their relative importance within undertaken projects. Building contractors tend to subcontract much of their production, because of the relatively wider range of technological inputs of building projects and liability concerns. On the contrary, non‐building contractors self‐perform much of their production, because of the relatively narrower range of technological inputs of their projects and higher fixed investments in dedicated assets.     

Construction equipment productivity estimation using artificial neural network model

Estimating equipment production rates is both an art and a science. An accurate prediction of the productivity of earthmoving equipment is critical for accurate construction planning and project control. Owing to the unique work requirements and changeable environment of each construction project, the influences of job and management factors on operation productivity are often very complex. Hence, construction productivity estimation, even for an operation with well‐known equipment and work methods, can be challenging. This study develops and compares two methods for estimating construction productivity of dozer operations (the transformed regression analysis, and a non‐linear analysis using neural network model). It is the hypothesis of this study that the proposed neural networks model may improve productivity estimation models because of the neural network's inherent ability to capture non‐linearity and the complexity of the changeable environment of each construction project. The comparison of results suggests that the non‐linear artificial neural network (ANN) has the potential to improve the equipment productivity estimation model.     

预应力锚杆(索)技术在山区边坡工程中的应用

依据山区边坡支护工程的实际情况,结合现场的锚杆、锚索试验,将预应力锚喷技术成功应用在山区边坡加固工程中,文章同时介绍锚杆、锚索的主要施工工艺、施工机具、施工材料、施工中出现的实际问题的处理解决以及施工质量的监控防范、支护变形的预警措施等。     

Factors influencing the risk of falls in the construction industry: a review of the evidence

Falls are a significant public health risk and a leading cause of non‐fatal and fatal injuries among construction workers worldwide. A more comprehensive understanding of casual factors leading to fall incidents is essential to prevent falls in the construction industry. However, an extensive overview of causal factors is missing from the literature. In this paper, 536 articles on factors contributing to the risk of falls were retrieved. One hundred and twenty‐one (121) studies met the criteria for relevance and quality to be coded, and were synthesized to provide an overview. In lieu of the homogeneity needed across studies to conduct a structured meta‐analysis, a literature synthesis method based on macro‐variables was advanced. This method provides a flexible approach to aggregating previous findings and assessing agreement across those studies. Factors commonly associated with falls included working surfaces and platforms, workers' safety behaviours and attitudes, and construction structure and facilities. Significant differences across qualitative and quantitative studies were found in terms of focus, and areas with limited agreement in previous research were identified. The findings contribute to research on the causes of falls in construction, developing engineering controls, informing policy and intervention design to reduce the risk of falls, and improving research synthesis methods.     

The Decentralization of Manufacturing Employment and the Role of Race: The Case of the Lakeside Press

This article presents an in‐depth case study of an inner city manufacturing facility, known as the Lakeside Press, which closed in 1993. It seeks to understand the relationship between the decentralization of jobs in the post‐industrial era and race through the consideration of one firm's experience as told by the company's workers. The basic question this article attempts to answer is what caused the outmigration of manufacturing facilities and jobs from inner city neighborhoods? What emerges from the experiences of this one firm is that the commercial arts printing industry had been undergoing technological innovation since the 1930s, and increased global competition since the Second World War. As southern blacks migrated north in search of jobs, this firm began to experience changes in the racial and ethnic composition of its workforce, as well as changes in the racial and ethnic composition of the firm's neighborhood. However, workforce integration in this central city manufacturing firm accompanied a de‐facto separation of races within the workplace. Typically, blacks and other non‐whites were relegated to unskilled positions within the firm where the chances for promotion were virtually non‐existent. This system of racial subordination was not challenged formally until the Civil Rights movement of the 1960s. The passage of the Civil Rights Act of 1964, combined with the assassination of Rev. Martin Luther King and the race riots of the late‐1960s, acted to undermine the informal organization of racial subordination within the Lakeside Press. The real and perceived costs of managing this transition in race relations, within the context of rapid technological change and global competition, appear to be linked to corporate decision making that would prompt the gradual decline of this inner city facility and the eventual elimination of over 7,000 jobs.     

Analysis of craft workers' and foremen's perceptions of the factors affecting construction labour productivity

Extensive studies have been conducted to examine the factors affecting construction productivity, but efforts have rarely been made to obtain craft workers' input. A survey was administered to 1996 craft workers throughout the US to quantify the workforce's perspective of construction labour productivity. Specifically, the survey measured the impact of 83 productivity factors, which had been identified through 18 focus group sessions with craft workers and their immediate supervisors on jobsites located throughout the US. Craft workers provide detailed insight into the factors affecting their daily productivity, and most of the adversarial factors affecting construction labour productivity can be addressed by jobsite management teams. The major findings indicated that craft workers and foremen share a general perception of the factors impacting on construction productivity; however, differences do exist. Specifically, foremen reported factors related to project management and engineering drawings having a more severe impact on their productivity compared to craft workers, and craft workers reported factors related to construction materials as having a more severe impact.     

The changing input structure of the US construction industry: a longitudinal analysis

Eleven input–output tables are used for analysing the technological changes of the US construction industry from 1947 to 2002. Over the years, the industry has been characterized by a significant input shift that reflects the evolution of the USA towards services and away from a manufacturing‐based economy. This evolution is also reflected in the 1997 adoption of a new classification system of the US industries by the Bureau of Economic Analysis (BEA). Changes are also found in analysing the direct requirements of two key sectors of the industry, residential and highway construction, during the 1967–1997 period. New materials and labour‐saving machinery have been some of the major drivers in the changing input structure of the two considered sectors. The study demonstrates the importance of using very long series of data and input–output tables with more than 400 industries for the further understanding of the secular changes of the construction industry and its constituent sectors.     

Real wages,amenities and the adjustment of working hours across local labour markets

High prices that are not offset by equally high incomes are often seen as an affordability problem. To get by, poorer workers in these areas might have to work longer hours. Alternatively, lower real wages might indicate a more desirable place to live and induce high-income people to trade off cash for leisure time. Both interpretations suggest a link between real wages and an individual's labour supply choice. Using panel data, I observe how working hours change, when workers move place. I find that working hours increase by 0.42% for a 10% decrease of local real wage. The effect is stronger for low-skilled workers at the bottom of the wage distribution, indicating an affordability mechanism that might further exacerbate inequality.     

Automated Object Identification Using Optical Video Cameras on Construction Sites

Abstract: Visual recording devices such as video cameras, CCTVs, or webcams have been broadly used to facilitate work progress or safety monitoring on construction sites. Without human intervention, however, both real‐time reasoning about captured scenes and interpretation of recorded images are challenging tasks. This article presents an exploratory method for automated object identification using standard video cameras on construction sites. The proposed method supports real‐time detection and classification of mobile heavy equipment and workers. The background subtraction algorithm extracts motion pixels from an image sequence, the pixels are then grouped into regions to represent moving objects, and finally the regions are identified as a certain object using classifiers. For evaluating the method, the formulated computer‐aided process was implemented on actual construction sites, and promising results were obtained. This article is expected to contribute to future applications of automated monitoring systems of work zone safety or productivity.     

钢筋数据从IFC向数控加工设备的传递

目前,在向钢筋数控加工设备录入钢筋尺寸时,仍然依赖于钢筋加工工人手工录入信息,这种方式既容易造成信息录入错误,也严重降低了钢筋加工效率。本文提出了一种从IFC文件提取钢筋加工数据,并将其以数字化方式传递给钢筋数控加工设备的方法。该方法从IFC文件中解析并提取钢筋实体信息,将其按BVBS格式进行编码后,再将编码转换为PDF417条码格式提交给钢筋加工工人;在钢筋加工厂,钢筋加工工人采用扫描二维码的方式将钢筋加工信息输入到MEP钢筋数控加工设备。该方法已在德州至上饶国家高速公路合肥至枞阳段项目得到成功应用。应用实践表明,该技术可将IFC格式的钢筋模型转换为数控加工文件,减少了工人读图、录入等中间环节,可以提高钢筋的加工效率和精度。     

BIM技术在建筑设备专业设计中的软件应用

当下BIM技术的快速发展,给建筑设计领域带来了继手绘到二维CAD之后又一次新的技术变革。从方案设计到现场施工,从信息采集到工程管理,BIM技术应用贯穿始终,同样给传统的设备专业设计带来了新的变革。软件作为技术应用的工具,必然对设计成果的实现产生重要的影响。本文主要以BIM核心建模软件AECOsim Building Designer(以下简称ABD)作为建模工具,通过三维设备建模、碰撞检测等功能应用,展现BIM技术在建筑设备设计专业中的软件应用价值。     

土方作业设备管理虚拟施工模型及仿真分析

以土方施工过程中的设备管理为研究对象,基于Petri网理论和工作流模型原理,构建了土方作业虚拟施工9元组有色Petri网仿真模型。模型描述了施工过程中工作流与信息流的动态变化,考虑了各种作业设备与施工约束条件之间的关系。根据施工作业的设备数量和项目成本等信息,对土方作业不同设备组合的施工情况、预计完成时间、成本及设备使用率进行仿真模拟和讨论。仿真模型基于CPNTools平台运行,通过项目现场收集数据进行模拟,对模型进行敏感度分析和模型验证,表明该模型能够提高土方作业施工过程的仿真结果准确度。     

An innovative approach for generation of a time location plan in road construction projects

Existing linear scheduling methods for earthwork activities lack accurate scheduling locations in road construction projects. Project planners and construction managers largely depend on subjective decisions for the allocation of resources at correct locations. This has caused uncertainties in planning and scheduling, and consequently delays and cost overruns of projects. Accurate information of working locations is vital for efficient resource planning, scheduling and equipment mobilisation. A theoretical framework for a virtual construction prototype model is developed using the theory of location‐based planning and this is used as the basis of sensitivity analysis to identify critical factors affecting road construction. An arithmetic algorithm is developed by incorporating road design data, sectional quantities, variable productivity data, unit cost, site access points and haulage distance. The model generates a time location plan automatically with the aim to provide location‐based scheduling information of earthwork activities. Weekly progress profiles, terrain surfaces, cost profiles and S‐curve are the other outputs of the model. Data and information collected from the case studies are used to demonstrate functionalities of the model. Critical factors controlling the productivity of earthwork activities such as different types of equipment, soil characteristics and site access points were used to display the sensitivity effect by means of ‘what‐if scenarios’. The model is a valuable tool in analysing impacts of different factors associated with productivity data and resource planning from location aspects in the earthwork construction projects.     

主体结构施工阶段扬尘监测与规律分析

为了了解建筑工程主体结构阶段的扬尘排放特点,掌握该阶段的扬尘分布规律以加强污染防控,改善施工作业环境。选取北京市两个典型住宅建设项目,以总悬浮颗粒物浓度作为监测指标,使用粉尘采样仪对主体结构施工阶段的各项施工活动进行扬尘浓度实地监测,汇总得到大量扬尘浓度原始数据。通过对比不同施工活动的扬尘污染状况,分析扬尘排放特点及主要分布规律。结果表明:主体结构施工阶段整体扬尘污染并不严重,不同施工活动排放的扬尘浓度存在明显差异,木工棚和道路两侧是扬尘污染严重区域。     

A model for automated monitoring of road construction

Monitoring and control of earthmoving operations is gaining an increasing interest. Manual monitoring and control of earthmoving operations have not yielded the expected results. Additionally, because manual monitoring is labor‐intensive, construction managers have to choose between monitoring based on rough estimates, or spending a lot of time collecting and processing data. The latter choice distracts them from many other important duties. The purpose of the present model is to automatically collect and process monitoring data providing the construction manager with real‐time control information. The model was developed for road construction. It uses GPS technology for automated data collection, logging the locations of all the earthmoving equipment while working on the project. Specially developed algorithms convert these locations to control information regarding productivity, duration (or progress) and actual consumption of materials. The model was implemented and tested for 3 weeks in a road construction project. The performance of four activities was measured by the model and compared to manual measurement of the same parameters. This comparison indicated that the model could reach a deviation of ±5%.     

Predicting movements of onsite workers and mobile equipment for enhancing construction site safety

Tens of thousands of time-loss injuries and deaths are annually reported from the construction sector, and a high percentage of them are due to the workers being struck by mobile equipment on sites. In order to address this site safety issue, it is necessary to provide proactive warning systems. One critical part in such systems is to locate the current positions of onsite workers and mobile equipment and also predict their future positions to prevent immediate collisions. This paper proposes novel Kalman filters for predicting the movements of the workers and mobile equipment on the construction sites. The filters take the positions of the equipment and workers estimated from multiple video cameras as input, and output the corresponding predictions on their future positions. Moreover, the filters could adjust their predictions based on the worker or equipment's previous movements. The effectiveness of the filters has been tested with real site videos and the results show the high prediction accuracy of the filters.     

如何加强建筑工程质量监督管理

通过对实际工程的监督管理,从施工前、施工中、竣工后三个方面总结了几点监督管理经验,提出了监督工作中应注意的原则和监督方法改进要注意的事项,以达到工程质量满足规范要求的目的。     

Real-time resource location data collection and visualization technology for construction safety and activity monitoring applications

Data to field operations of construction resources (personnel, equipment, materials) is vast, but the effort of collecting, analyzing, and visualizing is hardly ever taken. One main reason that limits higher quality in project site management decision making especially in resource intensive and complex operations is access to real-time information and subsequent technology that enables effortless data collection, processing, and visualization. Although recent developments in remote data sensing and intelligent data processing supplement manual data recording and analyze practices, few data on visualization tools in construction exist that gather data from dynamic resources and stream it to a field-realistic virtual reality environment in real-time. State-of-the-art technology in the field of real-time data collection and visualization is reviewed. A novel framework is presented that explains the method of streaming data from real-time positioning sensors to a real-time data visualization platform. Three case studies are presented which highlight its methods for recording data and visualizing information of construction activities in a (1) simulated virtual construction site, (2) outdoor construction setting, and (3) worker training environment. The results demonstrate that important construction information related to both safety and activity in field operations can be automatically monitored and visualized in real-time, thus offering benefits such as increased situational awareness to workers, equipment operators, or decision makers anywhere on a construction project or from a remote location.