Effects of Schedule Pressure on Construction Performance

Accelerating a project can be rewarding. The consequences, however, can be troublesome if productivity and quality are sacrificed for the sake of remaining ahead of schedule, such that the actual schedule benefits are often barely worth the effort. The tradeoffs and paths of schedule pressure—and its causes and effects—are often overlooked when schedule decisions are being made. This paper analyzes the effects that schedule pressure has on construction performance, and focuses on tradeoffs in scheduling. A research framework has been developed using a causal diagram to illustrate the cause-and-effect analysis of schedule pressure. An empirical investigation has been performed by using survey data collected from 102 construction practitioners working in 38 construction sites in Singapore. The results of this survey data analysis indicate that advantages of increasing the pace of work—by working under schedule pressure—can be offset by losses in productivity and quality. The negative effects of schedule pressure arise mainly by working out of sequence, generating work defects, cutting corners, and losing the motivation to work. The adverse effects of schedule pressure can be minimized by scheduling construction activities realistically and planning them proactively, motivating workers, and by establishing an effective project coordination and communication mechanism.     

Contemporaneous Time Series and Forecasting Methodologies for Predicting Short-Term Productivity

Productivity has a profound impact on projects that depend on time and cost of construction operations. In addition, time and cost estimates are derived from productivity. Thus, accurate prediction of productivity is essential to effectively plan and control construction operations. Predicting productivity of ongoing operations, however, is challenging. Due to dynamic and stochastic changes in productivity over time during construction, frequent and regular forecasting of short-term productivity is critical in managing ongoing operations. The present research investigated the characteristics of series of periodic productivity that should be taken into consideration to effectively predict short-term productivity continually and proactively. Given the identified characteristics, this study reviewed a few potential statistical methodologies that can make full use of contemporaneous time series data related to production for the purpose of predicting short-term productivity by using trend analysis. The methodologies were demonstrated in this paper using an example case, through which data processing and modeling procedure for modeling contemporaneous series data were explained.     

Integrated Design/Construction/Operations Analysis for Fast-Track Urban Freeway Reconstruction

The California Department of Transportation is rehabilitating or reconstructing deteriorated urban freeways using long-life (30+ years) strategies. These pavements were constructed between 1955 and 1970 with design lives of 20 years. This paper summarizes preconstruction analysis of the fast-track pavement reconstruction on Interstate-15 (I-15) at Devore which used two one-roadbed continuous (about 210 h) closures with round-the-clock (24/7) operations. The integrated analysis concluded that the one-roadbed continuous closures are the most economical scenario when compared to traditional nighttime or weekend closures from the perspective of schedule, delay, and costs. The preconstruction was validated with as-built construction and traffic performances monitored during construction. The construction management plan—including contingency, incentives, and critical path method schedule—was developed utilizing the Construction Analysis for Pavement Rehabilitation Strategies (CA4PRS) computer model. The results of this planning study are useful for transportation agencies in developing highway rehabilitation strategies that balance the maximization of construction productivity with a minimization of traffic delay.     

Integrated Simulation System for Construction Operation and Project Scheduling

Simulation modeling is important in predicting the productivity of construction operations and the performance of project schedules. It would be desirable if operation and project models are vertically integrated in practice. However, existing discrete event simulation systems do not allow integrating operation and project models. This paper introduces an integrated simulation system named “Construction Operation and Project Scheduling” (COPS). COPS analyzes the productivity of construction operations as well as the performance of a project schedule individually and jointly. It creates operation models, maintains these models in its operation model library, conducts sensitivity analysis with different resource combinations, finds the optimal resource combination that satisfies the user’s requirements relative to hourly production and hourly cost of the operation, feeds this information into a project schedule, and executes stochastic simulation-based scheduling. A case study is presented to demonstrate this integrated simulation system.     

Is Construction Labor Productivity Really Declining?

Macroeconomics data suggest that labor productivity declined significantly in the construction industry during the 1979–1998 period. However, microeconomic studies indicate the contrary. This paper critically examines the construction labor productivity macroeconomic data in the United States from 1979 to 1998 to determine their validity and reliability. Data collection, distribution, manipulation, analysis, and interpretation are reviewed and problems are identified. The paper also presents a comparison of construction and manufacturing labor productivity during this period. The main conclusion of the study is that the raw data used to calculate construction productivity values at the macroeconomic level and their further manipulation and interpretation present so many problems that the results should be deemed unreliable. The uncertainty generated in the process of computing these values is such that it cannot be determined if labor productivity has actually increased, decreased, or remained constant in the construction industry for the 1979–1998 period.     

Automated Collection of Mixer Truck Operations Data in Highly Dense Urban Areas

Our research has investigated the feasibility of directly sourcing autonomous operations data from a construction-vehicle positioning system, so as to enable productivity analysis and simulation modeling in the practical context of ready mixed concrete production and delivery. In this paper, we first review research efforts related to applying radio frequency identification tags and global positioning system for tracking construction resources and acquiring operations data in the field. We then describe the technical design and system components of an automated data collection (ADC) solution to accumulating concrete delivery operations data, which is extended from a construction-vehicle positioning system tailored for highly dense urban areas. We further elaborate on how our ADC system captures, transforms, and analyzes data of mixer truck operations. Truck-tracking experiment results based on field trials are presented to demonstrate the usefulness of data sourced from our ADC system with respect to: (1) analyzing truck-waiting time versus truck-unloading time on site; and (2) predicting truck’s plant-to-site travel time. In conclusion, the ADC solution resulting from this research not only allows sophisticated analysis of mixer truck resource utilization at concreting sites situated in highly dense urban areas, but also provides an accumulation of input data that will enable concrete plant operations simulation modeling.     

New Method for Measuring the Safety Risk of Construction Activities: Task Demand Assessment

The task demand assessment (TDA) is a new technique for measuring the safety risk of construction activities and analyzing how changes in operation parameters can affect the potential for accidents. TDA is similar to observational ergonomic methods—it does not produce estimates of probabilities of incidents, but it quantifies the “task demand” of actual operations based on characteristics of the activity and independent of the workers’ capabilities. The task demand reflects the difficulty to perform the activity safely. It is based on (1) the exposure to a hazard and (2) the presence and level of observable task demand factors—that is, risk factors that can increase the potential for an accident. The paper presents the findings from the initial implementation of TDA and demonstrates its feasibility and applicability on two different operations: a roofing activity and a concrete paving operation. Furthermore, the paving case illustrates how the TDA method can compare different production scenarios and measure the effect of production variables on the accident potential. The findings indicate that the method can be applied on activities of varying complexity and can account for several risks and task demand factors as required by the user. The selection of task demand factors is a key issue for the validity of the method and requires input from the crew and safety management. The limitations of the methodology and the need for further research are discussed. Overall, TDA provides a tool that can assist researchers and practitioners in the analysis and design of construction operations.     

Interpretation of Automatically Monitored Lifting Equipment Data for Project Control

Interpretation of the data that can be collected by automated monitoring systems on construction sites is the most significant challenge to providing useful management information. Distinct construction operations must be identified and associated with construction activities, so that they can be related to construction plans. Earlier research has indicated that construction equipment can be monitored conveniently and that individual equipment operations can be isolated and characterized. In this work, an approach has been developed for unique association of isolated equipment operations with planned construction activities. The approach is based on comparison of the values of various characteristics, calculated for each equipment operation, against preset filters of characteristic values for all expected basic construction activities. The composition of the set of characteristics is different for each data stream monitored and is dependent on the nature of the construction activities. The method has the distinct advantage of ensuring the uniqueness of each filter within the collection of filters when the system is calibrated at the start of any project, rather than during online data processing. In this way, rapid and accurate interpretation of monitored data can be guaranteed. The method was tested using data collected during construction of a high-rise office tower.     

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.     

Reengineering of Construction Management Process

Applying the business process engineering philosophy, this study focuses on developing a construction management process reengineering (CMPR) method to improve the efficiency of construction management. The CMPR method includes four phases, namely, process representation, process transformation, process evaluation, and reengineering activity. Using CMPR, inefficient operations within a construction company working process can not only be identified, but a new rational operation process can also be developed to improve management efficiency. In this way, the competitive ability of a construction company is also increased. This study argues for the need of a new research agenda in construction management in general. This is illustrated by information technology within construction—in particular, by examining the potential application of the reengineering philosophy. The research possibilities are identified and tested based on the implementation of the CMPR method. To some extent, this study establishes a new agenda of process reengineering for future research.     

Psychological testing in educational classification and placement.

Discusses 2 main issues—overrepresentation of minorities in all types of special education classes and bias in IQ tests that allegedly underlies such placements. The author identifies implicit issues in the IQ controversy, analyzes the classification system and its effects, and gives an alternative interpretation of classification and placement data. It is concluded that it is not tests themselves but test use that leads to discriminatory placement. Reforms in assessment procedures and classification systems are suggested. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Automation and Robotics for Construction

The potential for automated real‐time data acquisition, process control and robotics for remote, large‐scale field operations, such as those on construction engineering projects, is addressed. Classifications of technologies for automation and robotics in such operations include hard‐wired instrumentation, remote sensing, analog and digital telecommunications, optical (laser, infrared and fiber‐optic) data transmission, monitoring via microcomputer‐based instrument control and data recording, on‐site process control for fixed plants, partial or fully automatic control of mobile equipment, fixed‐based manipulators, mobile robots, communications between on‐site computers and automated machinery, electronic ranging and detection, and video‐image pattern recognition. Combining selected technologies with microcomputer‐based software could facilitate analysis, design and control decision‐making, and could provide a means of coordinating various discrete automated components or machines that must work together to perform field tasks. This paper also mentions categories of needs for such technologies on field operations, and potential barriers to implementation. Progress will depend on the interest and support of researchers qualified to advance this field.     

Comparative Study of Activity-Based Construction Labor Productivity in the United States and China

This research compares construction labor productivity (CLP) of the United States with its Chinese counterpart at the activity level to evaluate productivity differences between the two countries from an operational perspective. Supplementing other comparative construction studies measuring productivity by output value per person, this research examined CLP—measured by physical quantity installed per labor hour—based upon published national average productivity data. Sampled activities included earthwork, concrete, masonry, structural steel, waterproofing, and interior finishes. Paired comparisons (United States–China) of these selected activities were then analyzed and evaluated. The source of the U.S. labor productivity data was RSMeans Building Construction Cost Data, which was cross validated by data from the Walker’s Building Estimator’s Reference Book. The source of Chinese labor productivity data was mainly the Beijing construction quota, which was cross validated by Chinese quotas from several other cities and provinces in China. In terms of hourly output, significant differences were observed in many operational categories. To test the hypothesis that the labor-equipment compositions of the Chinese construction crews contributed to the labor-productivity gaps, a labor intensive factor (LIF) was introduced to measure the intensity of labor usage in a construction activity. Statistical analysis indicated that modest to strong correlations exist between the productivity differences and LIFs of the sampled activities. Chinese CLP significantly lags behind its U.S. counterpart in equipment-intensive construction activities. Smaller CLP gaps or comparable CLPs between the two countries were observed for labor-intensive activities. According to these findings, construction equipment efficiency appears to be a major factor contributing to the productivity difference between the two countries.     

Interactive 3D CAD for Effective Derrick Crane Operation in a Cable-Stayed Bridge Construction

The high expectation of esthetic and functional quality in modern civil infrastructure has resulted in the increased demand for long span bridges. In advanced or developing countries, long span bridges such as cable-stayed and suspension bridges are considered even as landmarks that symbolize the prosperity or culture of the region. These long span bridges require higher level of design and construction technologies than other types of bridges. In particular, the construction of cable-stayed bridges involves precise and sophisticated operation of construction equipment such as derrick cranes. However, it is not easy to plan the operations of a derrick crane before the actual construction process takes place. Unexpected spatial constraints in the construction site may hinder the smooth operation of a derrick crane, which leads to lower than expected productivity and safety. This study applies interactive three-dimensional (3D) computer aided design (CAD) to the derrick crane operation for the purpose of identifying potential problems. Construction managers can have the two way process with the 3D CAD system to interactively test their construction plans and scenarios. The case study shows that the interactive 3D CAD system significantly improves the constructability of the cable-stayed bridge construction.     

Benchmarking of Construction Productivity

Construction productivity has been a cause of great concern in both the construction industry and academia. Even though many companies have developed their own productivity tracking systems based on their experiences and accounting systems, none have been successful in establishing common definitions and developing a survey tool that collects standard productivity data at the appropriate levels. This research was initiated to establish a common set of construction productivity metrics and their corresponding definitions. As a result of this research effort, the Construction Productivity Metrics System (CPMS), which contain a list of direct and indirect accounts and 56 data elements grouped into seven major categories, was developed. The Construction Productivity Metrics System is a standard construction productivity data collection tool and provides a framework to report industry norms to benchmark construction productivity. Input from 73 industry experts was used in determining the 56 measuring elements and their corresponding definitions. Preliminary findings from initial sample of 16 industrial projects indicate that the productivity metrics can be produced and should be meaningful for construction productivity benchmarking. Because of the small sample size, more than general preliminary conclusion would be inappropriate. Based on the analyses, the developed CPMS is believed to be a reasonable productivity data collection tool and when sufficient data are available should be capable of producing reasonable industry benchmarks.     

Differences in Perspectives regarding Labor Productivity between Spanish- and English-Speaking Craft Workers

The influx of Hispanic workers helped the U.S. construction industry alleviate its shortage of craft workers in the last decade. In 2009, Hispanics accounted for nearly a quarter (22.5%) of the construction workforce in the United States. However, no research has been conducted to examine how various factors influence Hispanic craft workers’ productivity. This paper analyzes the data from a nationwide survey to obtain craft workers’ perspective on construction productivity. The respondents were categorized as Spanish- or English-speaking workers according to their declared primary language, irrespective of their ethnic background. The findings reveal that Spanish- and English-speaking craft workers generally agreed on the priority of the factors affecting labor productivity. However, Spanish-speaking workers rated factors associated with supervisor direction, safety, and labor more severely than English-speaking craft workers. Meanwhile, English-speaking craft workers perceived factors related to engineering drawing management as being more detrimental to productivity than did Spanish-speaking craft workers. Specifically, in comparison with English-speaking craft workers, Spanish-speaking craft workers experienced more severe issues with communicating with their supervisors, pay and monetary bonus for good performance, and lack of training on safety, health, and skills. These findings should be valuable for project management to effectively improve labor productivity of their Spanish-speaking craft workforce.     

Earthmoving Productivity Estimation Using Linear Regression Techniques

The problem of accurate estimation of earthmoving productivity has intrigued many researchers for many years, but there is yet no model that will predict the output of such operations with a satisfactory degree of confidence for all situations. The problem is exacerbated by the occurrence of hauler bunching that results in many deterministic models overestimating productivity. Systems analysis methods can be used, such as queuing theory or simulation, but they are generally impractical to the average site planning engineer. This paper investigates the results obtained from over 140 separate earthmoving operations taken from four different highway construction projects. Initially, the effects of bunching are determined, and many factors that influence productivity are identified. To investigate the relationships between earthmoving operating conditions and both productivity and bunching, and to develop a deterministic model that will enable earthmoving operations to be planned for many different situations with relative ease, stepwise multiple regression techniques are used. The results indicate that there is a strong linear relationship between operating conditions and productivity.     

Analysis of Factors Influencing Productivity Using Craftsmen Questionnaires: Case Study in a Chilean Construction Company

Improvement of productivity in construction has been a major industry challenge, given its high impact on project results. It has received increased attention from construction researchers promoting different enhancement actions, since analyzing factors affecting labor productivity is an instrumental part in this process. This paper focuses on identifying and understanding the productivity factors affecting projects in a Chilean construction company on the basis of questionnaires administered to both direct workers and midlevel employees. Analysis of the questionnaire results helped to determine organizational and managerial weaknesses and facilitated comparison of the findings with previous productivity studies. The results proved to be useful in developing recommendations for productivity improvements. The main findings indicate that the critical areas affecting construction productivity were related to materials, tools, rework, equipment, truck availability, and the workers’ motivational dynamics. These results are similar to those obtained in previous studies in the United States and in Chile. Salary expectations were found to be the main reason for turnover in the studied company, which was an aspect not mentioned in previous studies. Finally, additional analyses seem to show that some factors affecting productivity are common to construction projects across boundaries, therefore validating data aggregation and the possibility of learning from experiences in different locations and even separated in time of occurrence.     

Application of Lean Concepts and Simulation Analysis to Improve Efficiency of Drainage Operations Maintenance Crews

The City of Edmonton’s Drainage Operations branch oversees the inspection, maintenance, and repair of the city’s drainage network. This network covers an area of 700.6?km2 to serve the city’s growing population of nearly 1 million people. The activities performed by this division consume a large amount of funding and are, therefore, receptive to improvements in productivity. The study presented in this paper was conducted to develop improved work methods and engineered productivity standards for the various drainage operations. The study focused on six crews, which accounted for over 25% of the total drainage operations budget. The six crews were divided based on their respective duties: (1) cleaning mains by low pressure flushing (LPF); (2) cleaning mains by high pressure flushing; (3) scheduled mechanical cleaning of catch basins (CBC); (4) inspecting mains by televising; (5) commercial establishment investigation; and (6) service-line rodding and televising. The study utilized the concept of work simplification and focused on two crew activities—LPF and CBC work tasks—to improve crew work methods, to develop an established work standard, and to verify the proposed improvements based on the simulation model’s output. These activities are described in greater detail in two case studies. The work measurement concept was implemented to develop engineered productivity standards for the remaining crews in order to improve their productivity as well. This paper describes the application of an industrial engineering philosophy of work measurement—lean production theory—and the technique of simulation analysis to capture current work methods, generate and test alternative methods, and develop new productivity standards for drainage maintenance operations crews.     

Potentials for productivity enhancement from psychological research and development.

Reviews the nature of a pressing national problem—decline in US productivity growth—and discusses the vague concept of productivity as described in the current literature. The authors observed that traditional psycholgical approaches to productivity enhancement have tended to concentrate on employee or organizational productivity at the micro-economic level. It is argued that psychological research and development has much greater improvement potential at the macro-economic (i.e., national) productivity level. An example is given of possible contributions of psychological research and development with regard to improving the accuracy and utility of economic forecasts. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)