Journal of Construction Engineering and Management

In this paper, the theoretical basis for construction labor productivity measurement is presented. In particular, the theoretical basis for baseline productivity measurements is developed by examining a productivity database consisting of 23 projects involving masonry construction. An important hypothesis is presented showing that as the design becomes more complex, the baseline productivity worsens. It is also hypothesized that higher values of the coefficient of variation indicates a higher variability in management and craft skills and in the use of technology. Two measures are proposed to measure the performance of individual projects: The disruption index and the project management index. These two measures identify the best and worst performing projects. Cumulative probability distributions of the disruption index and the project management index were also developed to evaluate the 23-project database and compare it with other databases. The hypotheses developed from the 23-masonry project database were tested against an 8-project database of concrete formwork and a 12-project database of structural steel erection. Strong support for each hypothesis was found using the two additional databases.

The Parade Game illustrates the impact work flow variability has on the performance of construction trades and their successors. The game consists of simulating a construction process in which resources produced by one trade are prerequisite to work performed by the next trade. Production-level detail, describing resources being passed from one trade to the next, illustrates that throughput will be reduced, project completion delayed, and waste increased by variations in flow. The game shows that it is possible to reduce waste and shorten project duration by reducing the variability in work flow between trades. Basic production management concepts are thus applied to construction management. They highlight two shortcomings of using the critical-path method for field-level planning: The critical-path method makes modeling the dependence of ongoing activities between trades or with operations unwieldy and it does not explicitly represent variability. The Parade Game can be played in a classroom setting either by hand or using a computer. Computer simulation enables students to experiment with numerous alternatives to sharpen their intuition regarding variability, process throughput, buffers, productivity, and crew sizing. Managers interested in schedule compression will benefit from understanding work flow variability's impact on succeeding trade performance.

Efficient allocation of resources for construction planning activities requires construction planning resource requirements to be determined on a cost-effective and value-adding basis. However, although some research studies have indicated that increasing resource allocations to construction planning activities will lead to improved project performance, other research studies have indicated that investing in construction planning beyond an optimum point will lead to a deterioration in project performance. This study explored the concept of optimal planning of construction projects by examining 52 building projects undertaken in Australia. The relationships between planning input (ratio of planning costs to total project costs) and the probabilities of achieving poor performance and good performance were modeled using logistic, linear, and curvilinear regression analyses. A probable optimum planning input based on the sample studied was derived. It is suggested that any additional planning efforts beyond this optimum point would be essentially wasted because the additional planning costs would not achieve any savings in project cost but merely add to the overhead costs and therefore increase the overall project cost. A model for optimal planning is presented and discussed.

Application of partnering concepts on small construction projects by owners or government functionaries could result in substantial savings for private owners and public exchequers annually. This paper develops a concept for partnering for small construction projects based on recent management research and theories being developed in universities with the lessons learned from the U.S. Army Corps of Engineers experiences on partnering for large projects. The discussion addresses current attitudes toward partnering, particularly, in small (i.e., up to $3,000,000) private or government sponsored projects. An objective of this paper is to share the benefits of partnering on small construction projects, based on practices and experiences of the U.S. Army Corps of Engineers. A final objective is to develop a primer for construction practitioners.

Unstable subgrades are a major constructability problem for cold in-place asphalt recycling. The recycling operation is often performed by a train of equipment that mills, screens, crushes, and mixes the recycled material. This train is supported by the remaining pavement after the top has been milled off for recycling. Because the remaining pavement may be as little as 1 or 2 in. thick, good subgrade stability is required to support the train. A test is developed to assess subgrade stability using a dynamic cone penetrometer. The testing instrument is inexpensive and portable, and the initial testing program can be carried out for a typical project in 1 or 2 days. Guidelines are developed using data from a project that developed varying levels of subgrade instability during construction. The guidelines were corroborated by testing on other projects. The test may be used on projects having glacial till derived soil subgrades and in which equipment is supported by 1 or 2 in. of remaining pavement plus a soil-aggregate base. Additional research is recommended to develop test guidelines for different types of soils and different base support conditions.

This research examines how managers in contractors' organizations make decisions to adopt a new technology. This paper presents the decision-making processes managers use in the adoption of new technologies, the factors affecting these processes, and the strategies managers use to deal with the uncertainty involved in such decisions. The study focused on eight cases of adoption of two commercially available information technologies: (1) Electronic data interchange; and (2) 3D computer-aided design systems. This paper summarizes relevant background, briefly describes the decisions studied, presents the major findings, and highlights practical applications. The recommendations focus on the strategies that managers can use to increase the likelihood of successful adoption of new technologies.

This research is a numerical approach to the integration of the time and cost data sets for construction projects, which addresses the conflicts between them. Mathematical matrices are introduced to show the interrelationships between the time and cost data sets and their effect on each other, and to solve the conflict due to the differences between work breakdown structure and cost breakdown structure. Several matrices of time and cost data sets of construction projects are defined. The interrelationships among the matrices are investigated and several time- and cost-related matrix equations are presented. Based on the equations, this research develops a project planning and control algorithm that estimates the expected project cost and duration and evaluates the project economy using the matrix equations derived here. The matrix application is implemented through a spreadsheet program in which the matrices are automatically connected with each other. A case study involving a housing project is performed to verify the capability and utility of this computerized matrix application in integrating project time and cost.

Existing genetic algorithms (GA) based systems for solving time-cost trade-off problems suffer from two limitations. First, these systems require the user to manually craft the time-cost curves for formulating the objective functions. Second, these systems only deal with linear time-cost relationships. To overcome these limitations, this paper presents a computer system called MLGAS (Machine Learning and Genetic Algorithms based System), which integrates a machine learning method with GA. A quadratic template is introduced to capture the nonlinearity of time-cost relationships. The machine learning method automatically generates the quadratic time-cost curves from historical data and also measures the credibility of each quadratic time-cost curve. The quadratic curves are then used to formulate the objective function that can be solved by the GA. Several improvements are made to enhance the capacity of GA to prevent premature convergence. Comparisons of MLGAS with an experienced project manager indicate that MLGAS generates better solutions to nonlinear time-cost trade-off problems.

This research presents the activity-based construction (ABC) modeling and simulation method. ABC modeling (ABC-Mod) uses one single element (e.g., activity) for modeling general construction processes instead of multiple elements as required by current simulation systems. ABC simulation (ABC-Sim) executes the ABC model by manipulating activities in three stages: (1) Select activity; (2) advance simulation; and (3) release simulation entities. ABC-Mod and ABC-Sim constitute a unique simulation method, generally addressed as ABC. In summary, ABC is a general-purpose modeling and simulation method with an emphasis on construction application. Compared with existing simulation systems, it has all of the major features required for modeling and simulating the dynamic and random behaviors of a construction process. It requires no more knowledge to use than the critical path method does. Therefore, ABC is a simulation method for construction engineers and it has a potentially wide range of application in the industry.

Recently, the writers developed a general and powerful mathematical model for scheduling construction projects. An optimization formulation was presented with the goal of minimizing the direct construction cost. The nonlinear optimization problem was solved by the recently patented neural dynamics model of Adeli and Park. In this paper an object-oriented (OO) information model is presented for construction scheduling, cost optimization, and change order management (CONSCOM) based on the new construction scheduling model. The goal is to lay the foundation for a new generation of flexible, powerful, maintainable, and reusable software system for the solution of construction scheduling problems. The model is presented as a domain-specific development framework using the Microsoft Foundation Class library and utilizing the software reuse feature of the framework. The framework reuse architecture is more flexible and powerful than other reuse techniques such as components and patterns. A companion paper presents the implementation of the OO information model in a prototype software system for management of construction projects, called CONSCOM.

In a companion paper, an object-oriented (OO) information model was presented for construction scheduling, cost optimization, and change order management (CONSCOM), based on the creation of a domain-specific development framework. The framework architecture is developed using generic software design elements, called patterns, which provide effective low-level solutions for creating, organizing, and maintaining objects. The OO model has been implemented in a prototype software system for management of construction projects, called CONSCOM, using the Microsoft Foundation Class library in Visual C++. CONSCOM is particularly suitable for highway construction change order management. It can be used by the owner as an intelligent decision support system in schedule reviews, progress monitoring, and cost-time trade-off analysis for change order approval. The OO information model for construction scheduling cost management can be integrated into a concurrent engineering model for the architecture, engineering, and construction industry.

The current Asian financial crisis has put the role of risk management in the construction business into focus. For firms engaging in the international construction business, one of the most effective means of mitigating financial risks is through a joint venture (JV) with a local partner. There are, however, risks associated with an international construction JV. Based on a study by the writers on the risk factors and their mitigating measures, the most effective risk mitigating measures were categorized into eight groups. These are partner selection, agreement, employment, control, subcontracting, engineering contract, good relationship, and renegotiation. In this paper, a risk management model incorporating these measures was proposed. Three cases of international construction JVs were analyzed from the perspectives of the execution of these measures. It is hoped that this model would help construction firms in improving their decision-making process for their overseas ventures.