Journal of Construction Engineering and Management

The objective of this study was to assess the reliability and potential benefits of using the concrete maturity method in cold weather. This paper reviews the concrete maturity method, describes the technology and field observations, and discusses potential benefits of using concrete maturity in cold climates. The concrete maturity method is based on the idea that concrete strength development is strongly correlated with the curing temperature history. Modern sensor and processing devices (loggers) are able to measure and record the temperature of concrete over time. This information could be used to predict concrete strength over time. Findings from a case study in application of the maturity method in an industrial construction project in Edmonton, Alta., Canada indicated a significant potential time and cost reduction. The study also indicated that the concrete maturity methodology enables reliable quality control through the accurate estimation of in-place concrete strength. The real time information available through the concrete maturity method allowed the project manager to be proactive in managing heating and protection to ensure that the proper level of concrete strength was developed.

Under current scheduling practices, total float time is considered “free” and does not belong exclusively to any specific party in the construction process; rather, it belongs to the project and can be used by both owners and contractors to mitigate the potentially negative impact of delays. Utilization of float is, hence, on a “first-come, first-served” basis. Within this usage protocol and guided by the Common Law’s Proximate Cause principle, the party that encounters critical delays in the later stages of a project is more likely to be held responsible for delays to the overall project completion time. Given these practices, float ownership and its utilization has continued to become a major source of disputes when project delays occur. The objective of this paper is to introduce the concept of float preallocation and management for critical path method based construction schedules. The principles for preallocating and managing “total float” include recommending contract clauses to direct its use and to explain the manner in which responsibility for any resulting delay may be assigned. The paper also introduces a bookkeeping procedure to facilitate the application of this concept on project schedules. The proposed concept continues to recognize that total float is an asset for both parties.

The construction industry is responsible for environmental impacts that include air emissions, waste generation, and the use of land, water, and energy. However, most prior construction research attention has focused on these impacts only for material selection and building operation. The focus here is the environmental and energy implications of the construction process, specifically on-site energy consumption. Existing estimates of energy use and environmental emissions for the industry are tied to large construction vehicles, but other equipment consumes energy in various forms. This research creates a broader boundary for considering the energy use and environmental impacts of engines and vehicles used for construction activities by estimating these effects and comparing them to other national-level impacts. Results indicate that fuel use estimates for construction equipment are almost double the levels suggested by government reports; accordingly, air emission impacts are 30% larger for particulate matter and almost double levels of oxides of nitrogen and volatile organic compounds. Quantitative and qualitative analysis regarding how U.S. diesel engine and fuel regulations could significantly reduce air emissions from construction sites is also provided. If fully implemented, these regulations could initiate the manufacture and use of portable generators that make on-site electricity generation comparable to the electricity grid in terms of air emissions.

In evaluating closed-bid competitive procurement auctions, the most crucial issue is to determine the probability of placing a winning bid for a given markup level. There has long been disagreement on how this should be done due to the absence of a mathematical derivation of one of the main evaluation techniques—Gates’ method. Gates’ method is shown in this paper to be valid if, and only if, bids can be described using the proportional hazards family of statistical distributions. When markup values are included in Gates’ method, it is seen that the underlying statistical distribution required for the method to work is closely related to the Weibull distribution. Likelihood based methods are suggested for parameter estimation and an illustrative example is provided by analysis of Shaffer and Micheau's 1971 construction contract bidding data.

A new reinforcement system termed the prefabricated cage system (PCS) that can be used as an alternative to the rebar reinforcement cage is economically evaluated. PCS is a prefabricated reinforcement that enables easier, faster, and more reliable construction. Use of PCS shortens the construction schedule time and lowers total construction cost. This is important to both owners and construction contractors. The engineering economics methods presented in this paper would also be of interest to researchers. Reinforced concrete structures with PCS reinforced columns have been considered in this research, as it is one of the major applications of PCS. Various parameters affecting the economics of PCS are reviewed and a case study structure is analyzed comparing the costs of the structure with rebar reinforced columns to costs of the structure with PCS reinforced columns. The investigation shows that using PCS results in a 33.3% time savings and a 7.1% cost savings over rebar for each column. This results in an average of 3.6% savings on total project cost; an average of 22.2% savings on total column costs; 20.4% savings on total project time period, and 33.3% savings on columns construction time period. The cost savings are estimated based on production of small quantities of PCS reinforcement. Mass production of PCS reinforcement would result in even higher cost savings.

With a better understanding about the product market, industry practitioners can make more informed decisions for product specification, selection, and procurement. However, current approaches that support Architectural/Engineering/Construction (A/E/C) information acquisition do not provide a comprehensive market scan. While the Internet provides an ever-growing resource for product information, existing approaches have limited capabilities to make use of this virtual market. Therefore, the writers have developed a knowledge-assisted approach to specifically address the potential of the virtual market—help retrieve A/E/C product information, particularly information about different manufacturers, from the Internet. The paper introduces the building blocks of the developed approach, which includes domain knowledge utilization, information retrieval (IR) techniques, and strategies that incorporate domain knowledge into knowledge-supported IR approaches. Specifically, domain knowledge represented in the form of a thesaurus was used with query expansion strategies under the framework of an adaptation of the extended IR Boolean model. It was concluded from the prototype validation that domain knowledge can be extremely helpful when acquiring A/E/C product information from online resources using the developed approach.

Awareness of the construction environment can be improved by automatic three-dimensional (3D) sensing and modeling of job sites in real time. Commercially available 3D modeling approaches based on range scanning techniques are capable of modeling static objects only, and thus cannot model dynamic objects in real time in an environment comprised of moving humans, equipment, and materials. Emerging prototype video range cameras offer an alternative by facilitating affordable, wide field of view, dynamic object tracking at frame rates better than $1\mathrm{Hz}$ (real time). This paper describes a methodology to model, detect, and track the position of static and moving objects in real time, based on data obtained from video range cameras. Experiments with this technology have produced results that indicate that video rate 3D data acquisition and analysis of construction environments can support effective modeling, detection, and tracking of project resources. This approach to job site awareness has inherent value and broad application. In combination with effective management practices and other sensing techniques, this technology has the potential to significantly improve safety on construction job sites.

The safe and efficient operation of large equipment depends heavily on the skill of the operator. However, very little is known about how to evaluate what makes an operator safe and productive. This paper presents a quantitative approach for assessing the performance of backhoe operators. The approach takes advantage of electronic sensors that are built into a backhoe simulator providing data from both the operator controls and the backhoe arm itself. After a brief review of principles related to learning motor skills the paper describes a newly established backhoe simulator facility and reports about a series of experiments conducted to investigate the efficacy of measuring and comparing the performance of a backhoe operators. Several trained operators with differing work experiences participated in the study. The relevance of this work is in that the collected and analyzed data backs the well-documented correlations linking work experience with skill. It is believed that the utilization of quantitative skill metrics will lead to drastic improvements in the safety and productivity of large equipment.

This paper addresses both firm cultures and top leadership styles in construction firms in a West and an East-European country, the Netherlands and Lithuania. Human Resource managers filled in valid questionnaires during an interview on the premises of 16 construction firms in each country. The significant differences between the two countries pertain predominantly to the desired firm cultures and leadership styles. Construction firms in Lithuania strive toward more job autonomy, a more external orientation, an improved human resource orientation, a stronger interdepartmental orientation, and more of an improvement orientation in general. The Dutch respondents seek firm-culture improvements only in terms of a more external and interdepartmental orientation. Concerning desired transformational and transactional leadership, both leadership styles are significantly more desired by Lithuanian construction firms. Dutch top managers appear to rely already on transformational leadership with some transactional style components. Lithuanian managers have started to rely more on transformational leadership, whereas transactional leadership remains important in Lithuanian construction firms. Combining transformational and transactional leadership styles is highly recommended by current leadership research. Also, learning from “the best of both worlds” in terms of firm culture is recommended.

This note proposes a cost-effective construction method for large span cylindrical latticed shell structures. The method converts a latticed shell into a six-bar linkage, allowing the major part of the assembling work to be carried out at ground level. The structure is then lifted into position by activation of the predetermined mechanism mode and the structure is completed by adding additional members. In the note, we present the detailed construction procedures, together with some technical challenges that were encountered in practice. A discussion of the possible solutions to these challenges is also given, together with some suggestions for future similar applications of the method. From this study, researchers may borrow ideas to explore new construction methods, and practitioners of this technology can apply it more safely and properly.