Contractor Performance Evaluation for the Best Value of Superpave Projects

The best-value (BV) procurement process uses other key factors as well as bid price in the evaluation and selection of the best-performing contractor for the job. Contract time, lane rental, warranty, and quality of delivered product are examples of the key factors that indicate the contractor-expected performance. Literature on best value shows a need for analyzing the past performance of the contractor in similar jobs as an indicator of his/her qualification trend. This paper addresses this issue and proposes a methodology to incorporate quality of delivered product in the BV procurement system of asphalt construction. The paper uses past quality control (QC) testing results and utilizes Monte Carlo simulation to estimate the probability that the contractor gets full payment as an indication of qualification trend. The QC data were obtained from the Nebraska Department of Roads for a number of Superpave pavement projects. The results show the possibility of assigning a quality score for the contractor based on the past performance. This paper contributes to the current practice of best value with a new approach of employing QC as part of the selection process.     

Productivity Scheduling Method Compared to Linear and Repetitive Project Scheduling Methods

The analysis of project schedules is among the central tasks of construction managers. Parallel to the well-known critical path method, linear scheduling techniques have been researched. The two most fully developed existing methods, the linear scheduling model and the repetitive scheduling method, are reviewed. Based on a discussion of a published example, the new mathematical analysis method for linear and repetitive schedules is introduced. The productivity scheduling method is based on singularity functions that provide a flexible and powerful mathematical model for construction activities and their buffers that are characterized by their linear or repetitive nature. The steps of formulating initial equations, stacking and consolidating them, and deriving information about their criticality are described in detail. The mathematical approach of the new method allows an integrated treatment of activities regardless of the number of changes in productivity within them and does not depend on the graphical representation of the schedule.     

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.     

Improving Productivity on a Troubled Bridge Project

This paper presents a case study of a bridge constructed under adverse conditions in rural Florida. The major challenges facing the contractor were clearly identified through analysis. The bridge was constructed by an established, experienced bridge contractor that faced many daunting challenges in the construction of the bridge foundation, ranging from overdesign to the project manager managing his first construction project. However, the biggest challenge was unforeseen site conditions; namely, some of the most difficult clay imaginable through which to drive piles. These challenges forced the contractor into several tactical maneuvers. In sharing both the methods adapted by the contractor and the results of the adaptations, this paper quantifies for researchers and practitioners how a good contractor made sound, fundamental decisions to overcome severe challenges, improve productivity rates midproject, and eventually make the project a success. A seeming disaster early on, the project was eventually completed in less than the contract duration and at a sizable profit for the contractor.     

Reconciliation of Owner and Contractor Views in Heavy Construction Projects

Delay and loss of productivity are the two main types of damage experienced by the contractor when the owner issues a change order. Courts have recognized critical path method schedule analysis as the preferred method of identifying and quantifying critical delays. As for the inefficiency damages, there is no direct way of measuring inefficiency due to its qualitative nature and the difficulty of linking the cause of the productivity loss to the damage. Most of the scholarly work published in this area was based on data supplied by the contractors; and that explains why there are discrepancies between what the contractor asks for and what the owner believes the contractor is entitled to. This study addresses the need for a statistical model to quantify the productivity loss from verifiable site data such as owner’s daily reports, change orders, drawings, and specifications, rather than rely solely on contractor surveys. A model is developed and validated to quantify the productivity loss in pipe work in roadway projects due to the change orders. The productivity loss study analyzed two sets of data that include: (1) variables that predict which of the two parties, the owner and the contractor, contributed to the productivity loss; and (2) variables that predict, from the legal viewpoint, productivity losses which only the owner is responsible for. The study showed the difference between what the contractor asked for and what he/she is actually entitled to. This model can be used by both the owner and the contractor to quantify the productivity loss due to change orders, and to offer an objective approach to reconcile their differences. This study concludes with an example to demonstrate the use of the model.     

Contractor Selection for Design∕Build Projects

As traditional construction procurement approaches are found to be inadequate in meeting the demands and challenges of recent times, alternative procurement routes such as through management contracting or build-operate-transfer are increasingly being adopted. Although design∕build is one of the more popular alternative procurement methods that also has a long history, it does not appear to have well-established contractor selection procedures. This paper focuses on developing a model for contractor prequalification and bid evaluation in design∕build projects. For this purpose, it presents a comparative overview of some international practices in the design∕build contractor selection process. The overall objective is to identify the core aspects of selecting a suitable bidder in order to achieve the best “value for money.” The strengths and weaknesses of current practices of contractor selection are highlighted while identifying some of the best practices followed in design∕build projects by various clients.     

Performance Assessment of Construction Companies Integrating Key Performance Indicators and Data Envelopment Analysis

The web benchmarking systems broadly used in the construction industry (CI) are designed to provide results based on key performance indicators (KPIs). No insights concerning organization overall performance and improvements targets are available. This research aims to fulfill this gap using data envelopment analysis (DEA) as a method to complement the information provided by a set of KPIs. The methodology proposed is useful to all organizations involved in benchmarking routines. To enable a more realistic assessment of CI companies, two types of DEA models were used, one allows factor weights to vary freely and the other includes weight restrictions. These models assign an efficiency score to each organization, identifying efficient organizations and providing performance improvements targets for the others. To enable suggesting targets for all organizations, expert opinion was used to specify virtual units which were included in the efficiency assessment to define a practical frontier located beyond the productivity levels of the original DEA frontier. Based on a sample of 20 Portuguese leading contractors, the Portuguese web benchmarking system for CI, icBench, was used to demonstrate the advantages of integrating the DEA method with KPIs benchmark scores.     

Cumulative Effect of Project Changes for Electrical and Mechanical Construction

Change is inevitable on construction projects, primarily because of the uniqueness of each project and the limited resources of time and money that can be spent on planning, executing, and delivering the project. Change clauses, which authorize the owner to alter work performed by the contractor, are included in most construction contracts and provide a mechanism for equitable adjustment to the contract price and duration. Even so, owners and contractors do not always agree on the adjusted contract price or the time it will take to incorporate the change. What is needed is a method to quantify the impact that the adjustments required by the change will have on the changed and unchanged work. Owners and our legal system recognize that contractors have a right to an adjustment in contract price for owner changes, including the cost associated with materials, labor, lost profit, and increased overhead due to changes. However, the actions of a contractor can impact a project just as easily as those of an owner. A more complex issue is that of determining the cumulative impact that single or multiple change orders may have over the life of a project. This paper presents a method to quantify the cumulative impact on labor productivity for mechanical and electrical construction resulting from changes in the project. Statistical hypothesis testing and correlation analysis were made to identify factors that affect productivity loss resulting from change orders. A multiple regression model was developed to estimate the cumulative impact of change orders. The model includes six significant factors, namely: Percent change, change order processing time, overmanning, percentage of time the project manager spent on the project, percentage of the changes initiated by the owner, and whether the contractor tracks productivity or not. Sensitivity analysis was performed on the model to study the impact of one factor on the productivity loss (%delta). The model can be used proactively to determine the impacts that management decisions will have on the overall project productivity. They may also be used at the conclusion of the project as a dispute resolution tool. It should be noted that every project is unique, so these tools need to be applied with caution.     

A Fuzzy Decision Framework for Contractor Selection

Contractor selection is the process of selecting the most appropriate contractor to deliver the project as specified so that the achievement of the best value for money is ensured. Construction clients are becoming more aware of the fact that selection of a contractor based on tender price alone is quite risky and may lead to the failure of the project in terms of time delay and poor quality standards. Evaluation of contractors based on multiple criteria is, therefore, becoming more popular. Contractor selection in a multicriteria environment is, in essence, largely dependent on the uncertainty inherent in the nature of construction projects and subjective judgment of decision makers (DMs). This paper presents a systematic procedure based on fuzzy set theory to evaluate the capability of a contractor to deliver the project as per the owner’s requirements. The notion of Shapley value is used to determine the global value or relative importance of each criterion in accomplishing the overall objective of the decision-making process. The research reported upon forms part of a larger study that aims to develop a fuzzy decision model for construction contractor selection involving investigating multiple criteria selection tendencies of construction clients, relationship among decision criteria, and construction clients’ preferences of criteria in the contractor selection process. An illustration with a bid evaluation exercise is presented to demonstrate the data requirements and the application of the method in selecting the most appropriate contractor for the project under uncertainty. The proposed model is not intended to supplant the work of decision-making teams in the contractor selection process, but rather to help them make quality evaluations of the available candidate contractors. One major advantage of the proposed method is that it makes the selection process more systematic and realistic as the use of fuzzy set theory allows the DMs to express their assessment of contractors’ performance on decision criteria in linguistic terms rather than as crisp values.     

Construction Delays in Hong Kong Civil Engineering Projects

Construction delays are common in civil engineering projects in Hong Kong, inevitably resulting in contractual claims and increased project cost. This study was aimed, first, at gathering the perceptions of civil construction practitioners on how significant are the causes of delay; and, second, investigating whether the suggestions as stated in the report of the Construction Industry Review Committee (the Committee comprises members with good standing and knowledge in the construction and related fields as well as those from other professions who are responsible for examining the current state of the construction industry in terms of its output quantity, the quality of work, its environmental friendliness, site safety, its workforce and the system of supervision) are applicable to and effective at mitigating the corresponding delays with reference to a ranking order established using the mean score method. The extent of the differences in perception among the different respondent groups on these two issues was also examined using the rank agreement factor (RAF), percentage agreement (PA), and percentage disagreement (PD). The differences in the perceptions of the respondents on the significance of delays and the actual causes of delays for the six projects studied were also examined. The results of the study showed that the respondents tended to admit their own faults as shown in the top ten significant causes of delay. A strong consensus was found between the client and consultant groups on the significance of the various causes of delay (PA = 74%) and the effectiveness of mitigation measures (PA = 67%) compared with the other pairs of groups. The consultant and contractor groups held extremely different perceptions regarding the significance of various delay causes (RAF = 4.9 and PD = 32%) and the effectiveness of corresponding mitigation measures (RAF = 6.2 and PD = 47%). It is believed that the findings can provide much more insight for the construction practitioners as well as the researchers and thus help to improve the productivity and overall performance of civil construction projects in Hong Kong.     

Measuring the Productivity of the Construction Industry in China by Using DEA-Based Malmquist Productivity Indices

Data envelopment analysis (DEA) measures the relative efficiency of decision-making units and avoids any functional specification to express production relationship between inputs and outputs. DEA-based Malmquist productivity index (MPI) measures the productivity change over time. In this paper, the MPI is used to measure the productivity changes of Chinese construction industry from 1997 to 2003. The results of analyses indicate that productivity of the Chinese construction industry experienced a continuous improvement from 1997 to 2003 except for a decline from 2001 to 2002. It is found that there are gaps in productivity development level among western, midland, eastern, and northeastern regions in the Chinese construction industry. The DEA-based MPI approach provides a good tool to support setting up policies and strategic decisions for improving the performance of the Chinese construction industry and promoting the sustainable development of the industry between different regions.     

Simulation as a Tool for Pile Productivity Assessment

Subsurface obstacles, lack of contractor experience, site planning in addition to other factors complicated the installation process of pile foundation. Productivity and cost estimates for such a process are affected by these difficulties. Therefore this study focuses on the piling process productivity and cost assessment using simulation. Data were collected for this study through designated questionnaires, site interviews, and telephone calls to experts in different construction companies. Many variables have been considered in the piling construction process. Two simulation models have been designed and validated to assess piling process productivity and cost. Consequently, two sets of charts have been developed based upon the validated models to provide the decision-maker with a solid planning, scheduling, and control tool for piling process projects.     

Heterocycle-containing bisphosphonates cause apoptosis and inhibit bone resorption by preventing protein prenylation: evidence from structure-activity relationships in J774 macrophages

Recent evidence suggests that bisphosphonates (BPs) may inhibit bone resorption by mechanisms that lead to osteoclast apoptosis. We have previously shown that BPs also reduce cell viability and induce apoptosis in the macrophage-like cell line J774. To determine whether BPs inhibit osteoclast-mediated bone resorption and affect J774 macrophages by the same molecular mechanism, we examined the potency to reduce J774 cell viability of pairs of nitrogen-containing BPs that differ slightly in the structure of the heterocycle-containing side chain but that differ markedly in antiresorptive potency. In all cases, the most potent antiresorptive BP of each pair also caused the greatest loss of J774 viability, while the less potent antiresorptive BPs were also less potent at reducing J774 cell viability. Similarly, the bisphosphinate, phosphonoalkylphosphinate and monophosphonate analogs of BPs (in which one or both phosphonate groups are modified, giving rise to much less potent or inactive antiresorptive agents) were much less potent or inactive at reducing J774 cell viability. Thus, the structure-activity relationships of BPs for inhibiting bone resorption match those for causing loss of cell viability in J774 cells, indicating that BPs inhibit osteoclast-mediated bone resorption and reduce J774 macrophage viability by the same molecular mechanism. Loss of J774 cell viability after treatment with BPs was associated with a parallel increase in apoptotic cell death. We have recently proposed that nitrogen-containing BPs reduce cell viability and cause J774 apoptosis as a consequence of inhibition of enzymes of the mevalonate pathway and hence loss of prenylated proteins. In this study, the BPs that were potent inducers of J774 apoptosis and potent antiresorptive agents were also found to be effective inhibitors of protein prenylation in J774 macrophages, whereas the less potent BP analogs did not inhibit protein prenylation. This provides strong evidence that BPs with a heterocyclic, nitrogen-containing side chain, such as risedronate, inhibit osteoclast-mediated bone resorption and induce J774 apoptosis by preventing protein prenylation.     

Relationship between Changes in Material Technology and Construction Productivity

There have been substantial changes in both material technology and construction productivity over the past several decades. By analyzing the changes in both material technology and productivity among 100 construction activities from 1977 to 2004, this research examines the strength and types of relationships that exist within these two occurrences. Through analysis of variance (ANOVA) and regression analyses, the researchers found that activities experiencing significant changes in material technology have also experienced substantially greater long-term improvements in both their labor and partial factor productivity. The research did find that a stronger relationship exists between changes in material technology and partial factor productivity than in labor productivity. The research also found that changes in the unit weight of materials had a significant relationship to labor productivity, while changes in installation and modularity had a significant relationship to partial factor productivity. The research findings will help industry practitioners to better understand how they may leverage technology to improve construction productivity, while also helping researchers understand the theoretical relationships between technology and construction productivity.     

Project Delivery Systems and Project Change: Quantitative Analysis

Design/build has become one of the favored project delivery methods in the engineering construction industry. Numerous studies have advocated the use of design/build over the traditional design/bid/build delivery approach. A comprehensive analysis of 67 global projects from the Construction Industry Institute's database shows that design/build projects may not provide all the benefits to project performance. The study found timesaving was a definitive advantage of design/build project delivery, but, the positive effects of cost and productivity changes were not convincing. Based on the results of the study, the project management expertise and experience of the contractor may have a greater impact on project performance outcomes than focusing on project delivery strategy only.     

Impact of Shift Work on Labor Productivity for Labor Intensive Contractor

Generally, a contractor has three options in accelerating a construction schedule: working longer hours, increasing the number of workers, or creating an additional shift of workers. There has been a significant amount of research conducted on scheduled overtime on construction labor productivity. However, little information has been found in the literature addressing the labor inefficiency associated with working a second shift. This paper has qualitative and quantitative components. The qualitative part details why and how shift work affects labor productivity, and then addresses the appropriate use of shift work. The quantitative component determines the relationship between the length of shift work and labor efficiency. The results of the research show that shift work has the potential to be both beneficial and detrimental to the productivity of construction labor. Small amounts of well-organized shift work can serve as a very effective response to schedule compression. The productivity loss, obtained from the quantification model developed through this study, ranges from ?11 to 17% depending on the amount of shift work used.     

Exploring Coordination Goals of Construction Projects

Effective coordination has been regarded in both theory and practice as a critical factor of success in construction projects. Previous coordination studies have focused on the time spent on coordination, its frequency, and its relationship with performance. However, coordination goals have received less attention, and their relationships with coordination methods and performance are not known. This paper studies coordination methods and goals for construction projects to identify what coordination goals are adopted and to what extent goals are achieved. In the research process, eight coordination methods and six goals were derived. A questionnaire was designed accordingly and sent to seven contractors for survey. Follow-up interviews were conducted with three or four managers and engineers from each contractor. The analysis results indicate that most coordination methods have multiple goals; written coordination methods such as plans, schedules, reports, and contract documents tend to have appropriate goals; and projects performed well by using coordination methods effectively to achieve the coordination goals.     

Quantifying the Impact of Schedule Compression on Labor Productivity for Mechanical and Sheet Metal Contractor

In a typical construction project, a contractor may often find that the time originally allotted to perform the work has been severely reduced. The reduction of time available to complete a project is commonly known throughout the construction industry as schedule compression. Schedule compression negatively impacts labor productivity and consequently becomes a source of dispute between owners and contractors. This paper examines how schedule compression affects construction labor productivity and provides a model quantifying the impact of schedule compression on labor productivity based on data collected from 66 mechanical and 37 sheet metal projects across the United States. The model can be used in a proactive manner to reduce productivity losses by managing the factors affecting productivity under the situation of schedule compression. Another useful application of the model is its use as a litigation avoidance tool after the completion of a project.     

Contractor Performance Prediction Model for the United Kingdom Construction Contractor: Study of Logistic Regression Approach

An accurate prediction of contractor potential is of vital importance during contractor selection and evaluation process. Such prediction enables identification and classification of contractor performance to ease the selection process. This paper outlines the use of clients' tender evaluation preferences for predicting a contractor performance via a logistic regression (LR) approach. A total of 31 clients’ tender evaluation criteria were selected to develop a LR model for predicting contractor performance. The proposed model was developed based on 48 of United Kingdom public and private construction projects and validated in 20 independent cases. It was found that 75% of the cases correctly and the model statistically accurate for contractor performance prediction, where the input variables consist of nominal and interval data. The paper summarized techniques and advantages of LR analysis and discussed literature findings of contractor selection and evaluation methodologies undertaken by construction researchers and commentators from the United Kingdom and Northern America.     

Fuzzy Approach to Prequalifying Construction Contractors

Construction contractor prequalification (CCPQ) is a crucial decision making process to select capable potential bidders and ensure the success of construction projects. The purpose of CCPQ is to guarantee a contractor’s characteristic to meet the construction project’s requirements, which has been established worldwide as a standard practice. However, existing methods, i.e., marking method, subjective judgment method, etc., for contractor prequalification have been inadequate because it is difficult for decision makers to investigate contractor’s capabilities against inexact, vagueness, and qualitative criteria. The objective of this paper is to propose a fuzzy framework-based fuzzy number theory to solve construction contractor prequalification issues, which include decision criteria analysis, weights assessment, and decision model development. Finally, a case study for a tunnel construction project was used to demonstrate the feasibility of fuzzy approaches.