Journal of Construction Engineering and Management

This paper discusses the development and testing of a generic model that classifies constructability information for reinforced-concrete structural elements. It identifies decisions and factors affecting constructability and classifies them in a constructability information model (CIM). This model is tested with concepts from the literature and an industry survey. A refined structure is developed and evaluated for future work. The resulting CIM is a hierarchical breakdown of constructability concept attributes grouped in categories and subcategories. The major categories include design rules, lessons learned, external constraints, resources constraints, and performance information. Each concept is further classified by associating it with the facility processes and products that it affects. The CIM is found to be useful within the limits of its testing; reinforced-concrete structural elements. Further classification refinements are required to improve information storage and retrieval efficiency.

The consortium for advanced positioning system (CAPS) was formed in December 1992. The purpose of CAPS is to assist the Civil Engineering Research Foundation (CERF) with a Cooperative Research & Development Agreement (CRDA). CAPS will field and test a new real-time laser-based technology, real-time differential global positioning systems (DGPS), and total stations to determine areas of functionality and how to best integrate these measurement devices to improve the work process and as-building capabilities. The founding members of CAPS are Spatial Positioning Systems, Inc., Blacksburg, Virginia; Jacobus Technology, Inc., Gaithersburg, Maryland; Bechtel Corporation, San Francisco, California; and CERF, Washington, D.C. Integraph Corporation Huntsville, Alabama, joined CAPS in May 1993. The U.S. Army Corps of Engineers (Corps) is participating in CAPS through a CRDA with CERF. The objective of the CRDA is to create and field-test a system that improves quality, speed, and accuracy of construction layout and generates real-time as-builts. This effort encompasses the integration of the aforementioned new laser-based positioning system, total stations, and DGPS with computer-aided design (CAD)/ systems to form a real-time construction layout and as-built development system (RtCLADS). This paper presents three positioning technologies, their capabilities, their limitations, and the protocol needed to support the objectives of the CRDA.

Are some construction projects more prone to contract disputes than others? If so, can these projects be identified before construction begins? This paper describes research conducted with the CII Dispute Prevention and Resolution Task Force to answer these questions. This research analyzed the effect of different project characteristics on the occurrence of contract disputes. This paper explains the project characteristics that were evaluated, our data analysis techniques, and the conclusions that we made from this analysis. Three categories of project characteristics were considered: people aspects, process aspects and project aspects. The findings of this work are based on statistical analysis of data on the frequency and severity of disputes on 159 construction projects. A logistic regression model named Disputes Potential Index was created from this data set that predicts those projects that have a high likelihood of experiencing contract disputes. People, process, and project issues all play a role in predicting the likelihood of contract disputes. However, the fundamental conclusion from this research is that “people” hold the key to avoiding contract disputes.

The Salt River Project (SRP), located in Phoenix, Ariz., uses two different construction techniques to install conduit for new underground electrical systems in the Phoenix metropolitan area: open-trench cutting by conventional backhoes or wheel trenchers, and trenchless excavation techniques with minidirectional drilling machines and trenchless technology. This paper presents the results of research conducted to determine the comparative installation costs of conduit for SRP's underground electrical distribution, comparing the cost of conventional open trenching with minidirectional drilling. The study compared cost information that will aid SRP designers in optimizing the selection of site-specific underground electrical-conduit placement techniques. The research considered economies of scale, terrain, soil types, materials, and various common configurations of electrical conduit systems. In the years ahead, utility companies around the country may investigate the feasibility of minidirectional drilling to replace open trenching, especially in congested areas where the maintenance of good public relations is important. The analysis presented in this paper may provide a basis of comparison for other utility companies.

The environmental-cleanup market offers new and emerging business opportunities for the construction industry. However, these opportunities present substantial risks to contractors that decide to engage in cleaning up hazardous and toxic waste (HTW) sites. These risks can be attributed to the uncertainties of the technological and legal environment. Of all the risks present in this type of work, legal liability may be the most daunting. The intent of this paper is to provide a structured methodology to estimate risks associated with Superfund cleanup during construction and to quantitatively relate them to potential contractor liability. A decision-analysis technique that incorporates features from influence diagrams and decision trees was used to develop a model that estimates a contractor's liability. This model was developed through eliciting information from five industry experts. These experts are knowledgeable regarding the variables influencing events that effect a contractor's liability. The developed model is implemented in DPL, a decision software package, and applied to an actual Superfund project.

This paper presents a work-packaging–process model for petrochemical plant piping construction. The model's basic foundation is formed by identifying major decision variables that affect the work-packaging process. The model's main structure is developed by formalizing the evaluation processes of those variables through identification of related work-packaging conventions and associated data items. A series of heuristics are presented that can be used to define the work packages at the most detailed planning level. The model is developed using the data flow diagram (DFD) technique. DFD's are useful as modeling tools prior to automating any process because they help graphically identify conflicts and redundancies in information flow. The example in this paper demonstrates the potential of the work-packaging concept for modeling other planning, design, and construction work processes.

This paper outlines experiments performed on a simulation model of excavator-dump-truck–type earth-moving operations with the intention of indicating the parts of an earth-moving system to which the output is most sensitive. Response-surface methodology was used initially to indicate the relationship between two factors: the truck travel time, from loader to dump area and back; and the truck spot (or maneuver) time at the loader. This method indicated that the form of the relationship between these factors varied at different values but did not indicate how often factors affected the output. Full factorial designs were then done that not only were more economical in terms of the number of experimental runs required but also indicated that the most important factors are number of trucks, the haul and return (travel) time, the number of passes per load, and the loading rate. The simulation has highlighted a number of sensitivities. If load pass time is reduced then production will not increase if the operation is already under resourced. Conversely, production will not automatically increase by adding more trucks to the operation.

This paper introduces an algorithm that uses the Cyclic Operation Network Technique (CYCLONE), a discrete-event simulation method oriented to construction applications, to compute task late-time and float information. The deferment of tasks within acceptable limits can aid in achieving important planning objectives. Computing this information, however, has been confined almost exclusively to the critical-path method, despite the limitations of this technique to model repetitive task chains. The algorithm introduced here backtracks the event list resulting from the standard simulation scheduling algorithm, and provides allowable delays for a given resource utilization pattern. To ensure the proper sequencing of the back-tracking procedure, a standardized model development for CYCLONE is required. The technique introduced is appropriate for deterministic and statistically distributed duration estimates. An applicable example is developed throughout the paper to illustrate the procedure.

Concession agreements can be used by governments to induce the private sector to develop and operate many types of infrastructure projects. Under this type of arrangement, several private-sector companies join forces, become project promoters, and form a separate company that becomes responsible for financing, building, and operating the facility. Before this company can be formed, prospective promoters must determine how to fund the associated construction and startup costs. They must decide how much to borrow, how much to infuse from their own funds, and how much to raise from outside investors. Typically, such projects must repay any debt obligations through their own net operating income, and do not provide the lenders with any other collateral (off-balance-sheet financing). Thus, the possibility of a costly bankruptcy becomes much more likely. In this paper, we show that under these circumstances the amount of debt that a project can accommodate (its debt capacity) is less than 100% debt financing. The amount of debt that maximizes the investors' return on equity is less than the project's debt capacity, and the amount of debt that maximizes the project's net present value is even smaller. Exceeding these debt amounts and moving towards debt capacity should be avoided because it can rapidly erode the project's value to the investors. An example illustrates these concepts.

Establishing and maintaining a strategic advantage in a globally competitive business environment requires focus on electronic data management (EDM) technologies that facilitate work-flow automation and process reengineering. Effective implementation of EDM technologies requires a strategic, innovative, and cooperative approach to electronic document management. To date, a methodology for quantitative analysis of time and cost benefits attributable to EDM technologies has been difficult to structure due to the complexity of predicting the organizational changes resulting from their implementation. Additionally, implementation of EDM technologies will impact individual work task durations, work-flow precedence, and resource (labor) requirements. This is particularly true when multiple technologies are considered for concurrent implementation. This research developed a methodology for quantifying the time and cost benefits attributable to implementation of EDM technologies when applied to the major functional process of materials management. Data provided by leading engineering/construction companies were incorporated into four process models, each representing a distinct level of corporate information integration. The research shows that time and cost process benefits attributable to EDM technologies are significant.

This paper discusses the current attitude of large U.S. construction firms toward risk, and determines how these contractors conduct construction risk management. The paper is based on a survey of the top 100 large U.S. contractors. After discussion of the current views, the results are compared with a risk survey conducted by ASCE. The study shows that in recent years, contractors have been more willing to assume risks that accompany contractual and legal problems in the form of risk sharing with the owner. Risks of this type include change-order negotiations, third-party delays, contract delay resolutions, and indemnification and hold harmless. The survey also found that contractors currently assume the risk associated with actual quantities of work, a notable difference from the findings of the ASCE survey. Finally, the attitude of contractors toward the practice of defensive engineering is determined. This is significant, as no previous survey has addressed or sought to quantify allocation or importance of this task.

In the last decade, many departments of transportation around the United States have experimented with using the A+B bidding method. In this method contractors bid on the cost (part A) and on the time (part B), and the lowest combined bidder (A+B) is awarded the project. This paper analyzes 101 projects that have been awarded using this method and compares the results to the cost and the time of similar projects that were bid using conventional methods (cost only). The conclusions from the research show that substantial savings in construction time have been achieved when using the A+B method with almost no addition in cost. This was achieved by better planning and management of motivated contractors that were using the time element as part of their bidding strategy. The paper includes details on several case studies that demonstrate these results.

Materials-management systems should be integrated with computer systems that are used for design and scheduling. In addition, many materials management systems would benefit from integration efforts that would facilitate rule-based reasoning. These enhancements are facilitated by the use of an object-oriented methodology (OOM) data structure for the materials-management system. This paper discusses an OOM data model as it would apply to piping commodity materials. The paper also discusses the attributes incorporated into an OOM materials-management tutorial that was evaluated by industry professionals. Tutorial attributes include automatic commodity code generation, automatic takeoff execution, intelligent purchase order generation, and components of design and schedule integration. As part of their evaluation industry reviewers noted that OOM not only facilitates the development of more versatile systems, but also results in a computer code that is far easier to generate and less expensive to maintain.

Construction planners must select appropriate resources, including crew size, equipment, methods, and technologies, to perform the tasks of a construction project. In general, there is a trade-off between time and cost to complete a task—the less expensive the resources, the longer it takes. Using critical-path-method techniques, the overall project cost can be reduced by using less expensive resources for noncritical activities without impacting the duration. Furthermore planners usually need to adjust the selection of resources in order to shorten or lengthen the project duration. Finding optimal decisions is difficult and time-consuming considering the numbers of permutations involved. For example, a critical-path-method network with only eight activities, each with two options, will have 256 (2 ⁸ ) alternatives. Exhaustive enumeration is not economically feasible even with very fast computers. This paper presents a new algorithm using linear and integer programming to efficiently obtain optimal resource selections that optimize time and cost of a construction project.

Workers' compensation insurance is a significant cost component of construction labor. The manual rate for these insurance premiums is state- and trade-specific so the costs can vary considerably between geographic locations and between crafts. Another aspect of workers' compensation that should be understood is the experience modification rating (EMR), which is used to modify the premium paid. This modifier is essentially an incentive for firms to strive for good safety records, as firms with poor safety records will pay higher premiums. Examples have been developed to help clarify the manner in which the EMR values are impacted by different variables. Results show graphically how injury frequency has a larger impact on the EMR computation than does injury severity. The EMR is noticeably reduced when the hourly wages paid are increased. It is also reduced when the total wages paid per year are increased. Findings suggest that some degree of caution should be exercised if two firms are to be compared on the basis of their assigned EMR values.

This paper reviews the rules related to the enforcement of the contract liquidated-damages clause. The literature indicates that the clause will be enforced if: (1) The daily amount bears some resemblance to the actual damages that could be reasonably foreseen at the time the contract was written; and (2) the damage amount is difficult or impossible to estimate. Related to the reasonableness issue, courts will not permit the owner to use the clause to unreasonably coerce the contractor to complete the project on time or punish the contractor if he or she is late. The issue of difficulty in estimating the potential damages seems to be relatively minor. It is important that the estimates be related to the time the contract was signed. A number of cases were found where the actual damages were considerably more or less than the liquidated amount. This fact did not serve to waive enforcement of the clause. This paper discusses a number of issues related to liquidated damages and the assistance of an attorney may be needed.

This research presents a construction-space model that defines a collection of descriptive space types and typical patterns of space use in multistory building construction. Recent space-planning research describes characteristics of space and provides simple models of space demand for construction work to support automated space-planning methods. These simplified models cannot accurately represent the space needed for complex networks of work and material-handling activities in multistory buildings. The construction-space model identifies 12 construction-activity space uses, and their typical patterns. Repeatable patterns of space needs are recognizable and often occur independently in core, floor area, and perimeter work zones. The construction-space model characterizes these space needs to predict space demand, and thus supports the logical planning of productive work sequences. Through case-study research and site observation, the space model was found to accurately represent the use of space by construction activities in multistory building construction. If applied on site, this research helps construction managers plan and manage space.