Measurement and Risk Scales of Crane-Related Safety Factors on Construction Sites

This paper addresses quantitative measurement and risk scales of safety hazards on construction sites due to the work of tower cranes. Hazard measurement and risk scales are essential components of an integrated model aimed at quantitatively determining the safety level of individual construction sites, on a comparative basis. The paper focuses on two factors identified in earlier studies as considerably affecting safety on sites with tower cranes, “overlapping cranes” and “operator proficiency.” These two factors are inherently different from each other in their characteristics and therefore also in the methods used to measure both the factors and the risk resulting from them. A probability-based method was prescribed for the measurement of overlapping cranes, while the analytical hierarchy process method and knowledge elicitation from experts were applied to develop metrics for operator proficiency. In both cases, an intimate understanding of the crane work environment is necessary. The uniform format and specific methodologies presented here can be used in the development of measurement techniques and risk scales for other safety factors concerning crane operation on construction sites.     

Measuring Safety Climate of a Construction Company

Safety climate can benefit contractors, specialty contractors, and owners of industries by providing them with the knowledge of attitudes and perceptions that can help to consistently achieve better safety performance. The objective of this research was to determine safety climate that would enhance safety culture and positively impact perceived safety performance on construction projects. A safety climate questionnaire survey was conducted on the construction sites of a leading construction company and its subcontractors in Hong Kong. Approximately, 1,500 hard copy questionnaires were distributed and the response rate was excellent, resulting in 1,120 valid questionnaires being collected from 22 construction projects. By means of factor analysis, two underlying safety climate factors were extracted, accounting for 43.9% of the total variance. Multiple regression analysis confirmed that these climate factors, “management commitment and employee involvement” and “inappropriate safety procedure and work practices” were significant predictors of workers’ perceptions of safety performance. The findings indicated that the relationship between perceived safety performance and “inappropriate safety procedure and work practices” was inversely correlated. The results suggest that safety climate can be used as an effective measure of assessing and improving site safety for projects under construction. The findings of this study and the methodology might be useful for research at other construction sites in other regions and countries. This work provides useful information for project managers and safety practitioners who desire to improve safety climate and safety performance on construction sites.     

Benchmarking Studies on Construction Safety Management in China

This paper presents information by which to measure safety management performance on construction sites. In China, the conventional construction safety benchmarking approach is to assess safety performance by evaluating the physical safety conditions on site as well as the accident records, while no attention has been paid to the management factors that influence site safety. This paper is to identify the key factors that influence safety management and to develop a method for measuring safety management performance on construction sites. Based on the survey and interview data collected on safety management factors in 82 construction projects in China, the safety management index as a means to evaluate real-time safety management performance by measuring key management factors was developed. The quantified factors were compared with the commonly accepted physical safety performance index, which was derived from inspection records of physical safety conditions, accident rates, and the satisfaction of the project management team. Multifactor linear regression was conducted and the result indicates that safety management performance on site is closely related to organizational factors, economic factors, and factors related to the relationship between management and labor on site. Based on this benchmarking study, a practical safety assessment method was developed and then implemented on six construction projects. The results show that this method can be an effective tool to evaluate safety management on construction projects.     

A community based approach to bicycle helmet use counts

OBJECTIVE: Bicycle helmet use has become an important measure of the effectiveness of bicycle safety programs and the effectiveness of helmet legislation. Accounts of analytical comparisons of observation site selection methods are scarce. This report addresses this gap by reporting the relative effectiveness and costs of two alternative approaches to the selection of observation sites for helmet use counts. METHODS: The community based (COBA) method of site selection entailed asking community informants to identify locations frequented by young bicycle riders. In the bicycle club/map (CLMA) method, site selections were based on recommendations from club members of sites at which cyclists were likely to be found and through examination of maps, keying on local features. These alternative site selection methods were compared in terms of their overall and cost effectiveness in locating youth riders. RESULTS: Despite fewer observer hours and fewer sites in a sparsely populated rural county, the COBA method yielded greater numbers of riding youth and from 1.9 to 4.6 times more youth riders per observer hour than did the CLMA method in two densely populated suburban counties. In addition, costs per youth rider observed associated with the COBA method were 2.9 to 7.0 times lower than those associated with the CLMA method. CONCLUSIONS: Community based site identification is both more efficient in locating youth riders and more cost effective.     

Construction Safety Risk Mitigation

Construction safety and health management has improved significantly following the Occupational Safety and Health Act of 1970. In response to this legislation, contractors began implementing safety programs to reduce occupational safety and health hazards on construction sites. Researchers recently found that the current process of selecting specific elements for a safety program is informal. This paper describes the results of a recent study designed to determine the relative effectiveness of safety program elements by quantifying their individual ability to mitigate construction safety and health risks. In order to determine the effectiveness of individual safety program elements, the following research activities were performed: (1) an appropriate safety risk classification system was created using an aggregation of relevant literature; (2) highly effective safety program elements were identified in literature; and (3) the ability of each safety program element to mitigate a portion of each of the safety risk classes was quantified using the Delphi method. The results of the research indicate that the most effective safety program elements are upper management support and commitment and strategic subcontractor selection and management and the least effective elements are recordkeeping and accident analyses and emergency response planning. It is expected that the data presented in this paper can be used to strategically select elements for a safety program, target specific safety and health risks, and influence resource allocation when funds are limited.     

Dust Suppression Using Truck-Mounted Water Spray System

The control of dust on construction sites is an issue of concern of many communities that experience a high level of construction activity. Dust suppression typically involves using large water trucks to spray haul roads, material stockpiles, and other areas being worked by equipment. This method of dust control leads to labor, operating, and safety costs and complications that can limit and sometimes prohibit its implementation. Other spray methods that are cost-effective, easy to implement, functionally viable, and safe are needed that provide direct and effective dust control for each piece of equipment. This paper describes a research project to develop and evaluate a water spray system for suppressing dust emissions that is attached directly to a piece of earthmoving equipment, specifically a dump truck. The system consists of distribution hose, pipe, and spray nozzles attached to the perimeter of the truck body, and a water pump and water tank secured to the truck's frame. The system's design takes into account various operational and performance factors, including water consumption rate, spray configuration, equipment function and operation, dust suppression effectiveness, and cost of installation and use. It is expected that the system developed can play an effective role in minimizing dust emissions from construction sites.     

Identifying and Assessing Influence Factors on Improving Waste Management Performance for Building Construction Projects

Environmental sustainability has become one of the key drivers for continuous growth in the construction industry. Many project practitioners face challenging circumstances in finding an effective way to prevent pollution and minimize wastes by making the best use of the increasingly scarce natural resources. However, most of these efforts are focused on planning and/or design strategies; therefore, they fail to thoroughly cover the environmental issues based on the construction execution level. Further, there is a lack of quantitative measurement system and management-level guidance. To overcome these limitations, this paper proposes a new methodology that assists project managers to assess the performance level of a project in terms of waste management practice. This study is based on a two-pronged approach. One is the identification of the waste management influence factors that play an important role in decreasing waste and increasing recycled materials on construction sites. The other is the development of an assessment tool to measure the level of waste management performance for a particular project. As a result of this work, 59 factors were identified and an assessment tool was developed based on quantification of these factors. The tool has been proved to effectively measure waste management performance throughout four real-case validity tests. From the industry perspective, this paper contributes to establishing the environmentally sustainable production systems by providing the project stakeholders with an established set of influence factors and with a diagnosis tool for measuring their current performance. Additionally, project owners can use the output of the tool, especially the total index score, as a measure to benchmark the level of waste management for continuous improvement.     

Improving the Safety and Efficiency of Materials Transfer at a Construction Site by Using an Elevator

The aim of this study was to compare materials transfer at a construction site, either by carrying manually or by using an elevator. Data were collected at a construction site by using two methods: continuous automatic collection of data on the use of the elevator, and measuring and observing the transportation of some products when different delivery systems were used. Health and safety risks were at their highest when transporting products manually at construction sites. Risks decrease when vertical (an elevator) and horizontal (a wheeled device) transportation tools are used. A similar improvement as in health and safety risks can be seen in efficiency results: The working time needed with the elevator was 41% of the purely manual handling time. When wheeled devices were used, the transportation time was decreased to 16%. The early use of a permanent elevator succeeded well and its capacity was large enough. The effective use of the elevator and wheeled devices require that pathways are in better condition than normally.     

Accelerometer-Based Activity Recognition in Construction

Recognizing the activities of workers helps to measure and control safety, productivity, and quality in construction sites. Automated activity recognition can enhance the efficiency of the measurement system. The present study investigates accelerometer-based activity classification for automating the work-sampling process. A methodology is developed for evaluating classifiers for recognizing activities based on the features generated from accelerometer data segments. An experimental study is carried out in instructed and uninstructed modes for classifying masonry activities by using accelerometers attached to the waist of the mason. Three types of classifiers were evaluated, and multilayer perceptron, a neural network classifier, gave the best results. A 50% overlap for data segments enhanced classifier performance. The study showed that the utilization of best features instead of all features did not affect the classification accuracy significantly but reduced the run time considerably. An accuracy of 80% was obtained with accelerometers attached at both sides of the waist in an uninstructed environment. The results from preliminary studies have shown the potential of the proposed method for automating the activity recognition in construction sites.     

Contractors in Cyclical Economic Environments

This study investigated how the performance of construction firms during different extremes in the business cycle was impacted by a variety of the firms' characteristics. A performance index for a firm's relative market performance was devised and used with a step‐wise regression technique to model the relationships between operational variables and the performance index. Ten interviews wifh senior construction executives were conducted to guide the development of the model. The results show that a firm's relative market performance can be influenced by: Efforts in planning and control; control at firm level; effectiveness of project planning and control; efforts in marketing; effectiveness of marketing; subcontracting; long‐range planning; safety; geographic diversification; technological competence; and union∕open‐shop construction. Significance varied with cycle point and size. Recommendations are made on how to improve a contractor's performance in cyclical business environments.     

Geotechnical Investigation Strategies for Lunar Base

Geotechnical characterization of potential lunar sites will be a critical part of the planning and design process. The strategies used to conduct a geotechnical investigation will be dictated by the specific needs of the lunar base, the unique environment of the lunar surface, and general character of the lunar soils and rocks. This paper outlines some of the types of geotechnical information that will be important and identifies some of the more promising strategies which might be used to obtain such information in the lunar environment. Some of the most important geotechnical information for planning and site development will be related to construction in the lunar soil. In addition to construction concerns, geotechnical data for foundation design (or verification of predesigned foundations) will be needed. The geotechnical site‐characterization work should include geophysical techniques, supplemented by conventional mechanical boring and testing only to the degree necessary to correlate geophysical measurements with conventional soil properties and to investigate anomalies. Equipment used for geotechnical site characterization will also serve for mineralogical exploration. Several techniques for geotechnical investigation that may provide very useful information in an expedient manner are described. Geophysical methods include seismic and electromagnetic methods, including seismic surveys that utilize surface waves. Electromagnetic methods such as ground‐penetrating radar are fast, efficient methods for mapping the subsurface, although these techniques do not measure soil characteristics that can readily be correlated with engineering properties. Seismic methods provide information that may correlate with soil strength, compressibility, and excavatability. In‐situ physical testing will likely include penetration testing for direct physical measurement of lunar soil behavior.     

Downgrading Construction Incidents

The financial losses resulting from various incidents on typical building construction sites are reported. Field data was collected on three sites over a period of nine months. Incidents were recorded by three observers on a daily basis including data on the cause of the event, the direct losses incurred and the contractors involved. The 658 incidents reported were analyzed to determine the general characteristics of incidents, the level of field control possible and the incident costs. Overall losses on the individual sites are compared while combined results for all three projects are examined. Particular attention is paid to safety‐related incidents. Limitations of the monitoring program are discussed. The results indicate that downgrading incidents are responsible for a substantial loss on construction projects, however, the observations show that most losses could be eliminated through up‐graded on‐site management. Recommendations are made for reducing the losses by improving such management functions as planning, scheduling, follow‐up, equipment maintenance and problem documentation.     

Reliability Analysis of Shotcrete Lining during Tunnel Construction

To a tunnel under construction, a prompt assessment of the stability of the lining through in situ measured data is of practical importance both for the observational designing of the tunnel and to guarantee the safety of construction. Among all the parameters measured during tunnel construction, displacement measurement is the most convenient and at the same time, the most credible and cost effective method to track the performance of tunnel lining. The aim of this paper is to develop a displacement-based method suitable for conducting reliability evaluation of the shotcrete lining in the progress of construction of a tunnel. First of all, a performance function at the cross section is put forward. Next, formulas are listed to calculate the internal forces in a lining segment. Then, the variability of the basic random variables is explained. Further, a process to compute the reliability index through measured displacements is presented. After that, two case studies are done. Finally, the nature of the proposed method is observed and some remarks are made on further developments. The proposed method can meet the need of reliability evaluation of shotcrete lining during tunnel construction and also is certainly of theoretical significance to a large extent.     

Measuring the Performance of Value Management Studies in Construction: Critical Review

Value management (VM) is a useful method to use when dealing with issues such as budget and schedule challenges arising in the construction industry. However, little research has been done to measure the performance of VM studies, which has made many potential users reluctant to use VM. This paper presents a critical review of the development of performance measurement in general and the performance measurement in the construction industry, with a special focus on the performance measurement of VM studies in construction. The strengths and weaknesses of the existing measurement frameworks are investigated in the context of VM studies. It is concluded that traditional performance measurement of VM studies focusing on cost reduction is insufficient. Many other perspectives, such as clarifying objectives, and improving communication among stakeholders, should be considered seriously when making the measurement. This paper reveals that the existing frameworks to measure VM studies are inappropriate. It suggests that perspectives such as multicriteria measurement, flexible framework for different practice, and benchmarking to identify best practice could be adapted to develop a performance measurement framework for VM studies.     

Work Sampling Can Predict Unit Rate Productivity

Various methods are employed to measure labor utilization during power plant construction, one of which is work sampling. Work sampling attempts to evaluate how the work force spends its time at work. This provides timely information to management in order to determine whether corrective action or detailed study is needed to achieve a higher degree of efficiency. However, the effectiveness of work sampling in demonstrating true labor performance has not been statistically verified using data collected at construction sites. This study collects 45 work sampling data points from 11 nuclear power projects and 4 fossil fuel power projects. the relationship between work sampling and productivity has been strongly supported by this statistical analysis. This study also verifies that work sampling is a good labor productivity indicator as well as a useful predictor in a productivity projection model.     

Improved Baseline Productivity Analysis Technique

Previous studies have aimed to develop effective methods to derive baseline productivity (BP) for labor-intensive activities in construction sites. However, there are two different definitions of BPs: one is defined as a performance benchmark of best practice and the other as a standard reflecting a contractor’s normal operating performance. It is necessary to clarify the difference between the two definitions and their corresponding BPs. This research introduces data envelopment analysis (DEA) as a new method for deriving BP and compares DEA with the other four BP deriving methods. DEA is concluded as the best method in terms of objectivity, effectiveness, and consistency to find BP that represents the best performance a contractor can possibly achieve. With the capability of deriving productivities of multi-input and multi-output activities, the proposed DEA has raised the scale of labor productivity from the level of single factor productivity to total factor productivity which will help construction researchers and managers to evaluate performances of interests in a much more effective way.     

Effect of Safety and Environmental Variables on Task Durations in Steel Erection

In spite of the efforts by government agencies, labor organizations, and researchers in the field of health and safety, injuries and fatalities continue to affect the construction industry. In 2002 the construction industry had the undesirable distinction of having two of the most dangerous occupations in the United States, with fatalities among structural steel workers at 58.2 per 100,000 workers (fourth highest rate) and among construction laborers at 27.7 per 100,000 workers (ninth highest rate). Costs associated with construction accidents, such as increased insurance premiums and medical expenses, and loss of productivity are also concerns in the industry. It has not been demonstrated how unsafe working conditions affect worker performance, and the impact of unsafe work practices on worker performance has not been quantified. This paper describes a methodology that included direct observation of steel erection activities and statistical analysis of task duration data. The data collected at steel erection sites included safety conditions such as the use of personal protective equipment (PPE), elevation of the work area, environmental conditions such as temperature and humidity, and worker performance in the form of task durations. Analysis of variance (ANOVA) analysis of 186 of steel erection task durations collected over a six-month period showed that the use of personal protective equipment (PPE), the time of day during which the operation was being performed, the elevation at which the work was being performed, and the presence of decking below the work area had statistically significant effects on the durations of steel erection tasks.     

Development and Initial Validation of Sustainable Construction Safety and Health Rating System

This paper presents a study to develop and validate a sustainable construction safety and health (SCSH) rating system. The rating system provides an opportunity to rate projects based on the importance given to construction worker safety and health and the degree of implementation of safety and health elements. A Delphi survey using an expert panel of 12 experienced safety and health professionals representing different sectors of the construction industry was employed to develop the SCSH rating system. The study resulted in a rating system consisting of a total of 50 safety and health elements organized into 13 categories. Each category contains safety and health elements which carry credits based on their effectiveness in preventing construction worker injuries and illnesses. The rating system was initially validated based on data from 25 construction projects and found to accurately represent the safety performance of large projects. The SCSH rating system can be used as an effective tool to develop and plan construction safety and health programs and evaluate the potential safety performance of construction projects.     

Site Safety Management in Hong Kong

The construction industry is well known for its complexities and inefficiencies in dealing with human safety and construction processes. The industry itself has been notorious for its high casualty records over many years. Especially in Hong Kong, the concept of improving safety in construction sites has only started to be developed in recent years. The government has set up new ordinances and regulations, and companies are willing to invest more on this issue before the construction commences. Nowadays in Hong Kong, from the small to the sizable, nearly all construction companies have their own site safety plans indicating safety guidelines and protective measures to achieve certain safety standards on the project sites. However, when viewing the past records published by the Labour Department, no trend in injury frequency reduction was noted. Consequently, an effort has been made in this report to compare three different site safety plans of three renowned civil and building contractors were investigated. Moreover, in order to review the effectiveness of the prevailing site safety plans and the safety performance of the contractors, a questionnaire survey targeting some site staff was conducted to solicit their opinions on the implementation of site safety plans. From the results of the questionnaire survey the authors determined that the construction companies are now regarding occupational health and safety as prerequisites of all the site operations.