Journal of Construction Engineering and Management

By definition, any activity not on the critical path must have float. The concept of float in the critical path method relates to how long an activity can be delayed before it becomes a critical activity. For linear construction activities, however, the concept of float is somewhat different from that of traditional scheduling techniques. Rather than start time and duration being the main attributes of float, production rate is a more fundamental attribute of a linear activity. As such, for float to be meaningful for a linear activity, it must be reflective of the activity's major characteristic. Rate float captures this characteristic and presents information to construction planners and managers in terms that are meaningful for linear projects. This paper describes rate float as it applies to the linear scheduling model developed by Harmelink and Rowings in 1998.

In recent years, many departments of transportation in the United States have started to apply the A + B bidding method in highway projects in order to reduce construction time and minimize its associated traffic congestion and adverse impact on local economies. The application of this method places an increased pressure on contractors to minimize both the time and cost of highway construction. This paper presents a practical model for optimizing resource utilization in highway projects that utilize the A + B bidding method. The model is designed to minimize the total combined bid by identifying the optimum crew formation and the optimum level of crew work continuity for each activity in the project. The model is developed using a dynamic programming formulation and is incorporated in a Windows application that provides a user-friendly interface to facilitate the optimization analysis. An application example of a highway project is analyzed to illustrate the use of the model and to demonstrate its capabilities.

An optimal repetitive scheduling model for precast production with the consideration of resource constraints and resource sharing is proposed in this paper. A repetitive schedule, like precast production, needs to take into consideration the impact of limited resources, including equipment (such as cranes, forms, and steaming curing facilities) and skilled labor, on production makespan. Moreover, to economically and effectively utilize these valuable resources (such as cranes and work crews), it is worth taking resource sharing into consideration in precast production. A genetic algorithm-based searching technique is adopted to establish an optimal resource-constrained repetitive precast production scheduling system with the consideration of resource sharing. The system can effectively provide the optimal or near-optimal combination of production durations, resource amounts, and minimum makespan under the constraint of limited resources and with the consideration of resource sharing.

This study was undertaken to identify the most significant gaps between the potential benefits of applying constructability principles to Alberta, Canada, industrial projects and the benefits typically realized in industry practice. This study also aims to gain an understanding of the barriers that commonly restrict constructability benefits. The data for this survey was obtained by administering a survey based on the Construction Industry Institute's 17 constructability principles. The results of this study indicate collaborative industry effort should be focused in the areas where the largest gaps currently exist between potential and realized benefits. These include among other things, involvement of construction in the design phase, building mutual trust, respect, and credibility between project planners, designers, and constructors. As the examples cited in this study illustrate, significant gains in project cost, schedule, performance, and safety can be achieved when the above prescription is followed. For example, savings of 30–40% in the total installed cost for facilities are quite readily achievable.

This study is focused on developing an automated site layout system for construction materials. The system, MaterialPlan, including a geographic information system (GIS) based cost estimates system integrated with material layout planning, is a new tool to assist managers in identifying suitable areas to locate construction materials. As tabulation of all project quantities is calculated using GIS, linkages are established between the graphical features of detailed design and the related estimating quantities. Based on information regarding quantities and locations of the materials required in the project, this study identifies the suitable site to store the materials. Using the concept of “searching by elimination,” the system develops a heuristic approach, modeling the process of human decision making to generate potential sites for placing the materials. An objective function called the proximity index is developed to determine the optimal site. In conclusion, MaterialPlan demonstrates that GIS is a promising tool for solving construction layout problems and thus opens up a new way of thinking for the management of spatial information in construction planning and design.

The world economy is becoming more global due to agreements such as the “Uruguay Round” in the General Agreement on Tariffs and Trade. The globalization of the construction industry provides tremendous opportunities for contractors to expand into new foreign markets. However, international construction involves all of the uncertainties common to domestic construction projects as well as risks specific to international transactions. Consequently, in opposition to the worldwide globalization trend, only 19% of the U.S. top 400 contractors actively seek international contracts. This paper discusses current approaches related to entry decisions into international construction markets. It then develops a comprehensive approach for making stable and systematic go/no-go decisions for international projects. Finally, a pilot study is used to demonstrate and validate the approach.

The management of construction claims is the greatest challenge that is facing contractors in today's vacillating business environment. Construction projects are becoming increasingly susceptible to a variety of factors that give rise to time extension and cost recovery. Although the construction business environment has moved toward partnering arrangements in recent years, the number of contractual difficulties continue to rise. Thus, the construction industry needs to develop methodologies for construction claim management that should overcome their current problems. While some practitioners have been using some kind of a procedure for claim management process framework measuring tool, a written exposition of such an instrument is not widely available in the literature. This paper presents the principles that underly construction claim process and gives a generic framework that aims at facilitating measurement of construction claim process as one of the strategies for improving construction business processes. It also presents a survey of Malawian construction contractors' performance on the construction claim process framework. The results show a low awareness of such a construction claim process-measuring instrument.

Site layout planning is a complicated issue because of the vast number of trades and interrelated planning constraints. To unfold its complexity, this paper aims to confine the study to a particularly defined area of construction: the structural concrete-frame construction stage of public housing projects. In this study, optimization of the tower crane and supply locations is targeted, as they are the major site facilities for high-rise building construction. A site layout genetic algorithm model is developed and a practical example is presented. The optimization results of the example are very promising and demonstrate the application value of the model.

Detailed design of building projects is a complex multidisciplinary process highly dependent upon effective aggregation of individual designs to produce a coherent set of final design documents. Throughout the detailed design process, changes are frequently introduced and need to be properly managed among the various members of the design team. This paper presents an information model for storing design information, recording design rationale, and managing design changes. The proposed model is built around a central library of generalized building components that can be used to describe a complete building project hierarchy. Each component allows the designer to store desired performance criteria and related design rationale. Each component is also sensitive to its own changes and automatically communicates such changes to affected parties through preset communication paths. The model, as such, provides improved design coordination and control over changes, thus helping to increase the consistency and productivity of the overall design process. Conceptual details of the model are described in this paper, and model implementation into a collaborative design system is presented in a companion paper.

The objective of this paper is to utilize recent advances in information technology and computer collaboration tools to improve coordination and increase productivity in the design of building projects. Based on a structured information model, presented in a companion paper, a collaborative design system is developed incorporating (1) a client-server environment for representing building data, recording design rationale, and effectively managing design changes; and (2) Internet-based collaboration tools for sharing documents, reviewing changes, and conferencing among remote design participants. Implementation issues and the perceived changes imposed on the traditional design process are discussed, and an example application is worked to demonstrate the applicability and features of the developed prototype. The developments made in this paper provide guidelines for modeling complex information-dependent processes in the construction domain.

Accidents occur in all types of construction activities. The accident causation process is complex. Accident prevention requires a comprehensive understanding of this complex process. This paper proposes a conceptual, but practical, model of accident causation for the construction industry, highlighting the underlying and complex interaction of factors in the causation process. The model describes the constraints and responses experienced by the parties involved in project conception, design, and construction, which may affect accident causation. This paper details theoretical findings of research currently being conducted at UMIST. Both proximal and distal factors are considered (for example, operative factors, site environment and systems of work, and project management and organizational issues). A study of 500 accident records provided by the U.K. Health and Safety Executive shows that accidents in construction projects involve inappropriate construction planning (28.8%), inappropriate construction control (16.6%), inappropriate construction operation (88.0%), inappropriate site condition (6.0%), and inappropriate operative action (29.9%). Data currently available are, in some respects, inadequate and will need to be supplemented, in the future, by extended accident investigations.