Journal of Construction Engineering and Management

Masonry construction over the last century has undergone radical changes that have led to specific improvements in construction performance due to the advent of large-sized blocks, innovative methods like surface-bonded masonry, partially grouted masonry, and dry-stacked/mortarless masonry using interlocking blocks. This paper outlines relative productivity assessment of conventional and interlocking-block masonry with different construction methods. To measure the utilization of time by the members of the team, work sampling (adopting the 5 min rating technique) was used. The frequencies of occurrences of each work category, namely direct, indirect, and noncontributory, have been established. Due to the variation in the noncontributory work component for different methods of construction, the net output has been expressed as output per productive hour. Productivity enhancement of 80–120% was observed for dry-stacked masonry and 60–90% more for thin-jointed and mortar-bedded interlocking-block masonry than that of conventional masonry.

One principal element of the construction cost of a cast-in-place prestressed box girder concrete bridge is the erection of falsework. This paper presents the results of the analysis of labor-hours and quantity of work in erecting the falsework for 20 such bridges. Analysis of the bridge data has shown that the best productivity for falsework erection occurs when constructing a low structure on relatively flat ground. Location and design factors such as steep slopes, traffic openings, and tall structures, as well as such construction techniques as the use of cranes or lifts and the type of bent material selected, can reduce falsework erection productivity (measured through installation data for setting of pads, constructing bents, setting stringers, and rolling out the soffit) by over 50%. A belief network diagram was constructed to show graphically the falsework erection productivity influences identified through a study of the 20 bridges. With the collection of additional data, the belief network can be used to calculate a total falsework erection productivity value based on dozens of combinations of influencing factors.

New management thinking, like that of lean production, has suggested that better labor and cost performance can be achieved by improving the reliability of flows. In this context, lean thinking portrays reliable flows as the timely availability of resources, i.e., materials, information, and equipment. Little attention has been given to labor as a flow. Further, little discussion can be found related to flexible capacity management strategies. Efforts to utilize lean thinking in construction, so far, have generated limited evidence to support the need for more reliable labor flows. This paper investigates the lean principle that more reliable flows lead to better labor performance. Actual data from three bridge construction projects are examined to document the instances of poor flow (resource) reliability and its effect on labor performance. Inefficient labor hours are calculated. The results show that there is strong support that more reliable material, information, and equipment availability contributes to better performance. However, the projects showed considerable deficiencies in the utilization of the labor resource. It is concluded that lean improvement initiatives should focus more on workforce management strategies to improve labor utilization that will lead to better labor performance.

The Occupational Safety and Health Administration (OSHA) investigates most worker-related fatalities and many accidents involving serious injuries. A research study was conducted that focused on the data OSHA accumulated on construction worker accidents involving falls. In the construction industry, falls are the most frequently occurring types of accidents resulting in fatalities. The purpose of the study was to identify the root causes of fall accidents and to identify any additional information that might be helpful in reducing the incidence of construction worker falls in the future. While data from January 1990 through October 2001 were examined, particular emphasis was placed on fall accidents that occurred in the last 5 years of this time interval, a period when more data were accumulated and coded in the OSHA investigation reports. Results show that most fall accidents take place at elevations of less than 9.15 m (30 ft), occurring primarily on new construction projects of commercial buildings and residential projects of relatively low construction cost. Furthermore, experience does not seem to diminish accident occurrence; hazards are often misjudged by workers; and various other patterns can also be observed. Most alarming, the results show that fall accidents account for a growing proportion of the total number of construction worker fatalities.

The objective of this research was to develop a model that estimates future highway construction costs in Louisiana. The model describes overall highway construction cost in terms of a highway construction cost index. The index is a composite measure of the cost of construction labor, materials, and equipment; the characteristics of contracts; and the environment in which contracts are let. Future construction costs are described in terms of predicted index values based on forecasts of the price of construction labor, materials, and equipment and the expected contract characteristics and contract environments. The contract characteristics and contract environments that are under the control of highway agency officials, can be manipulated to reflect future cost-cutting policies. Application of the model in forecasting to highway construction costs in Louisiana shows that the model closely replicates past construction costs for the period 1984–1997. When applied to forecasting future highway construction costs, the model predicts that highway construction costs in Louisiana will double between 1998 and 2015. Applying cost-cutting policies and assuming input costs are 20% less than anticipated, the model estimates highway construction costs will increase by 75% between 1998 and 2015.

This paper proposes a probabilistic model for the calculation of project cost contingency by considering the expected number of changes and the average cost of change. The model assumes a Poisson arrival pattern for change orders and independent random variables for various change orders. The probability of cost overrun for a given contingency level is calculated. Typical input values to the model are estimated by reviewing several U.S. Army Corps of Engineers project logs, and numerical values of contingency are calculated and presented. The effect of various parameters on the contingency is discussed in detail.

Competitive bidding is the means by which pricing of numerous services takes place. Optimization models have been developed to support bidding, but no consistent and structured methodology has been followed in evaluating those models. This paper provides such a methodology and demonstrates it in the comparison of three bidding optimization approaches aimed at profit maximization. The methodology represents a modification and refinement of previously used evaluation approaches. In addition, the methodology incorporates the determination of an upper bound on effectiveness in order to provide an indicator of how much improvement in effectiveness remains. Real construction bidding data are used to demonstrate the comparison of the optimization procedures.

Identifying and removing constraints from bottleneck activities help to reduce uncertainties in construction processes and increases the transparency of project management. The present means of look-ahead planning do poorly in resolving hidden constraints in the supply chain and information flow. Accordingly, work plans are vulnerable to the uncertainties that result in flow variation. It has been realized that reducing and eliminating critical constraints through better means of look-ahead planning are the keys to achieving reliable workflow and, consequently, increased productivity. This paper presents a constraint-based planning tool, Integrated Production Scheduler (IPS), to enhance planning reliability while adopting lean construction principles and the theory of constraints. Unlike the critical path method, the IPS models two additional types of constraints related to resource supply and information exchange. It employs four activity buffers: working, shielding, pulling, and screening for managing critical constraints and shielding the production from uncertainties. The implementation of the IPS is prototyped as a distributed scheduling system using Internet technologies such as Java and XML. It facilitates setting up a transparent project management environment where faster communication and active collaboration among project members are achievable.

The customization of products and services—characterized by a customer-integrated process for product design, manufacturing, marketing, and support services—now represents an important competitive strategy in business environments. This trend has given birth to a new concept in the operations management field, called mass customization, which refers to the ability to provide individually designed products and services to every customer through high process flexibility and integration. This business approach has been identified as a competitive strategy by an increasing number of companies, to which the building industry is no exception. Buyers are eager to purchase flats (apartments) with high levels of customization that contain a high number of items designed and built in accordance with their needs and desires. This paper addresses the design of an object-oriented model to allow an agile interaction between consumers and companies, toward the implementation of mass customization in the building sector. The object-oriented model provides a dynamic and flexible tool to support company-customer information exchange and to keep the dispersed information consistent.

Quality function deployment (QFD) is a process that has been used for managing the development of new manufactured products. In this process, both spoken and unspoken needs of the customers are determined, prioritized, and translated to design parameters. Such design parameters are assigned specific target values and are frequently checked against customers’ needs throughout the development cycle to ensure customers’ satisfaction with the end product. This paper describes a pilot study in which QFD was implemented in a design-construction project. The project scope involved the preparation of a conceptual design for a modern large-size classroom for college students. The design was intended to become a model for the university’s future classrooms. The study proved that QFD could be successfully adopted in engineering-construction projects. However, the study identified a number of implementation challenges. In addition, more applications are necessary to take the process throughout the full project delivery cycle, as the pilot study involved only the preliminary engineering and conceptual design phase.

Production building in the residential sector is often described as the portion of the construction industry that is most like the manufacturing sector. In modern tract construction in the United States, a small number of models are generally repeated several times in a relatively confined area, using specialized trade contractors to complete each phase of each home. Management of the handoffs between predecessor and successor trade contractors is therefore a critical component in the successful completion of a residential project. In order to bring more reliable planning to this process, a workflow-leveling strategy known as even flow production has come into use in the industry in recent years. Even flow production is a strategy intended to reduce the variability in the workflow for trade contractors in the process, thereby gaining production efficiencies. In practice, different operational definitions are in use. This paper describes a series of simulation experiments to identify the management implications of two common strategies (activity-based versus start-based). A special-purpose simulation template was built for the Simphony environment for this purpose. The pace chosen for the flow of activities was found to significantly affect the speed at which the subdivision was completed. The even flow strategy was found to affect the subdivision completion time only slightly, but to have a significant impact on workflow variability and management effort. Control of the pace of starts of only the first activity exhibited nearly the same degree of variability as if the pace of starts were matched to a sales pace.

Previous studies comparing OHSAS 18001: 1999 (Occupational Health and Safety Assessment Standard) with the old ISO 9001: 1994 (Quality Assurance Standard) have found compatible requirements that warrant their integration. This study examines the compatibility of the recently released ISO 9001: 2000 (Quality Management Standard) with OHSAS 18001: 1999 for the purpose of integration. A survey of 96 construction firms in Singapore was conducted for this study. Among those who are considering or are already OHSAS 18001: 1999 certified, findings were obtained on the possibility/difficulty and benefits/costs of integration of OHSAS 18001: 1999 and ISO 9001: 2000. Industry concerns relating to potential problems and implementation challenges were discussed. The study concludes that the newly introduced ISO 9001: 2000 standard serves as an opportune platform for construction firms to consider certification to OHSAS 18001: 1999 through an integration exercise.