Journal of Construction Engineering and Management

Construction, with its uniqueness and unusual operational characteristics, faces special handicaps dealing with process planning and control. In order to study the productivity and the resource efficiency of construction operations, one has to consider the impact of a wide variety of factors. This paper presents a framework for the identification of sources of process delays. It focuses on the study of the relationship between storage limitations of flow units within a production system and the productivity of the system. In addition, the effect of breakdown delays in combination with different storage conditions are discussed. The CYCLONE (CYCLic Operations Network) modeling and simulation technique was used as an analytical tool for this study. Enhancements to the existing Micro‐CYCLONE simulation program, which enable it to handle the necessary new modeling elements, will be introduced. The analysis shows that generally higher storage constraints result in higher overall productivity. However, certain constraints and process structures present specific conditions where the general rule does not apply.

There are many demands for technological advancement in construction but the mechanisms to bring this about are not well understood. This paper describes the process that resulted in an example of construction innovation, the use of the “up/down” construction method on the Rowes Wharf project. The first section includes a review of alternative methods for foundation construction, a description of the innovation, an explanation of the process of innovation, and a summary of the results. The description of the process gives the background of the project team, reviews the alternatives considered, identifies the steps in evaluation and implementation, and gives the problems. The second section then compares this innovation with a model of the process of innovation on a construction project and presents conclusions and practical applications for industry professionals seeking to increase the rate of innovation in their firms and researchers seeking to better understand this complex process. The major insights from this example of innovation concern the owner's organization, concurrent conceptual and detailed planning, and the need for iteration in selecting design approaches and construction methods.

The objectives of project control systems go beyond documentation to recognition of problems and evaluation of their causes. Through the use of broad information systems, a construction manager today is able to assemble a wide variety of data about his projects or programs. Retrieval, analysis, and interpretation of the meaning of these data, however, usually require the user to have detailed knowledge about the structure and content of the data base and the use of a data retrieval language, and have further programming skills to allow the computer to perform analyses. The work reported in this paper has three goals: to ease retrieval with near‐natural language query capabilities; to acquire and accumulate data access and analysis knowledge; and to exercise such knowledge to find patterns in project data. This paper reports on the development of a knowledge‐based query system, Expert‐MCA, developed by coupling the techniques of data‐base management systems, natural language processing, and knowledge‐based expert systems for use in the U.S. Army military construction program (MCA). The system architecture is presented, followed by a description of how knowledge is represented and processed in answering English‐like queries. Finally, examples are used to explain its capabilities in more detail.

In a major earthmoving operation involving a loader and trucks, a careful selection of equipment size can result in substantial savings both in time and cost. When planning an earthmoving operation, usually the size of the loading unit is selected based on the production required. The optimal truck capacity is either selected by comparing the production cost of various truck capacities or by using a rule of thumb that recommends truck capacities four to five times the capacity of the selected loader. The objective of this study is to investigate the optimal truck capacity for various loader sizes. To achieve this objective, specifications and costs of a number of loaders and trucks commonly used in earth‐moving are used.

The construction of oil and gas facilities on integrated barge units (IBUs) is presented. This technique of construction could be useful in remote wilderness locations. The function of the facilities, alternate construction techniques, and the effects of location and terrain conditions are discussed. Construction costs using the IBU method are estimated to represent a 16% savings in capital costs over modular construction, and facility startup can be advanced by up to five months. Using an IBU instead of a stickbuilt facility may represent a 44% savings in cost. In addition, maintenance, abandonment, and site rehabilitation are discussed and compared. For every aspect of cost presented, the integrated barge unit offers a less costly alternative. Depending on the specific location, this technique could also represent less of an impact to the surrounding environment than the more traditional techniques of oil and gas facility construction.

This paper presents a general model for the formulation and solution of the risk‐sensitive dynamic decision problem that maximizes the certain equivalent of the discounted rewards of a time‐varying Markov decision process. The problem is solved by applying the principle of optimality and stochastic dynamic programming to the immediate rewards and the certain equivalent associated with the remaining transitions of a time‐varying Markov process over a finite or infinite time horizon, under the assumptions of constant risk aversion and discounting of future cash flows. The solution provides transient and stationary optimal decision policies that depend on the presence or absence of discounting. The construction equipment replacement problem serves as an example application of the model to illustrate the solution methodology and the sensitivity of the optimal policy to the discount factor and the degree of risk aversion.

Geotextiles and geocomposites are relatively new materials in engineering and their developments have proceeded differently in different countries. This paper reviews the uses and developments in the United Kingdom. It covers a wide range of materials by type and composition in reinforcement, the impact of actions under patent legislation to protect the Reinfored Earth System, and a summary of some of the main trials carried out or still in hand. Examples of application in remedial and marine works are given. The types and use of geocomposites are covered together with biodegradeable materials. Future developments in the United Kingdom are then considered.

The means by which weather is addressed in public works construction contracts were examined through a survey. The agencies included in the study consisted of all state departments of transportation, several district offices of the United States Corps of Engineers, and various supervisor's offices of the United States Forest Service. The focus of the study was to determine how weather conditions, particularly conditions that could adversely impact construction schedules, are addressed in typical agency contracts. Results show that the practices of the Corps of Engineers and the Forest Service offices are relatively consistent within their own respective agencies, however, major differences are noted between these agencies. Less consistency was observed between the practices of the various state departments of transportation.

As a key technology, construction robots are expected to improve working conditions, reduce accidents, and increase construction productivity. Robotics in the construction industry is a young and fast‐growing interdisciplinary field. However, it is only recently that the subject has begun to emerge as a coherent but multidisciplinary activity. Although the construction industry so far has managed to develop highly productive systems without the help of robots, there are specific areas of application in which robots could benefit the industry. This paper describes prototype construction robots developed by a Japanese contractor in the areas of rockwool spraying, concrete and wall finishing, silo lining, and radioactive concrete cutting. Application of these robots in traditional construction sites, and their implementation in new construction fields are discussed. To obtain the full benefit of robots, it is necessary to change the whole construction system like factory automation did in the manufacturing industries. Newly developed construction systems should achieve the building design and construction planning just suited to robots.

Resource leveling is needed in construction to avoid the difficulties associated with the large variations in resource usage. This paper presents an integer‐linear optimization model of resource leveling (single resource, continuous activities) which guarantees the optimal leveling. The objective function of the model minimizes the absolute deviations between the resource requirements and a uniform resource level, between consecutive resource requirements, or between the resource requirements and desirable nonuniform resource levels. The model requires as input the critical path method (CPM) scheduling results, from which the constraints and objective function of the model are established automatically by an interface program. Extensions of the model to multiple resources and trade‐off of cost scheduling are suggested. The model is applicable to activity‐on‐arrow, activity‐on‐node, and precedence networks and is intended for small‐ to medium‐sized construction projects.

The results of a questionnaire survey that reports the construction equipment policy in the Engineering News Record rated top 400 construction companies are presented. Special attention is paid to equipment financing, replacement analysis, equipment standardization, safety, and maintenance management. The questionnaire responses are cross‐tabulated in regard to annual volume and type of construction (heavy versus nonheavy).