Journal of Construction Engineering and Management

Managing heavy-pressure vessel lifts on construction sites requires planning, arranging adequate crane support, and preparing collision-free rotation (from a horizontal position to a vertical position) of the vessel. Generally, selecting mobile cranes and developing engineered lift studies for vessels are done using two cranes and analyzing the lift for each crane individually on the basis of the selected cranes’ lift-capacity specifications provided by crane manufactures. This practice is relatively costly and time-consuming. Optimizing the mobile cranes’ use and location is also difficult. To assist in the field operation of mobile cranes and to provide engineers with a planning tool, this paper presents a methodology to carry out such a lift utilizing only one crane. Using the developed methodology and mechanism, heavy vessels can be rotated off the ground (in the air) with one crane. The proposed mechanism is supported with a mathematical model that has been developed into a computer system and has been integrated with a previously developed crane selection and ground pressure calculation system and crane database. The developed system provides users with a lift study analysis for a given configuration as well as simulation results with interactive graphics to assist in the selection of an optimum configuration. This research is important as projects involving heavy lifts need to reduce the cost and time associated with construction operations.

The observational method involves recurrent updating, and according to European standards, it is an optional method when geotechnical conditions are difficult to predict. A method for the application of value of information analysis in rock mass characterization for tunnels is demonstrated in a generic case of a feasibility study of a tunnel in hard rock. Two alternative grouting designs are analyzed to find the most suitable design for the geological conditions on site and whether information from investigations is of value in the decision-making process. The uncertainty in the grouting result is described by means of a beta distribution for each alternative design. The probabilities of different geological states are based on 200 stochastic simulations of the rock mass. It was found that value of information analysis contributes to good structure in geological surveys when the geology is difficult to predict and when repeated updating is necessary. The prescribed method is a tool to design well-motivated investigation programs where geotechnical value is weighed up against execution costs.

Despite the considerable scholarship focused on infrastructure investment in the developing world and the substantial sums of money spent each year on developing-country infrastructure, little attention has been given to understanding the drivers of conflict that shape the trajectory and cost structures of these massive investments. The manifestation of conflict among stakeholders in infrastructure projects ranges from the renegotiation of contract terms by project partners to popular protests among consumers of privatized services. The principal objective of this research is to identify combinations of country, project, and stakeholder factors that are associated with the emergence of legal and political conflict within natural gas and oil pipeline projects and water supply concessions and leases. The analysis includes data from 26 infrastructure projects spanning 31 countries and uses an analytical approach derived from Boolean algebra. Country-level characteristics, such as extent of democracy and rate of international NGO membership, are found to be important elements in the recipes for conflict among water supply projects but not for pipeline projects. Local impacts such as service price increases (water supply) and limited provision of oil and gas to the project host country (pipelines) are also important drivers of conflict for both subsectors. The involvement of one or more international financial institutions is also associated with the emergence of conflict in projects. Contrary to expectations, public consultation is associated with conflict in both subsectors. Overall, the study findings suggest that several factors associated with conflict in infrastructure projects can be minimized with careful project design.

Guarantee provision in privately financed infrastructure projects implemented as build-operate-transfer/public-private-partnership (BOT/PPP) arrangements is not uncommon in many countries, and Indonesia is no exception. But, given that the government budget is, in most if not all cases, not unlimited, there must be a selection of BOT/PPP projects posing proposals for seeking government guarantees. This paper presents a project selection methodology under the chance-constrained goal-programming framework in the context of the Indonesian BOT/PPP infrastructure industry. The ultimate objective of the selection is to result in a portfolio of guaranteed projects that brings maximum welfare gain to the economy as a whole, maximum total net change in financial net present value but, at the same time, puts the government at the lowest fiscal risk for a given budget constraint. The proposed methodology allows the government to examine relationships among the expected total payment, budget-at-risk allocated, and a desired confidence interval of actual payment not exceeding the budget-at-risk. The government can also compare two or more alternative scenarios and choose the optimal one that delivers the highest value for the money. To illustrate the model application, without sacrificing the generality of the proposed methodology, a much-simplified hypothetical case is presented, examined, and discussed.

The ability of construction contractors to plan and manage cash flow is critical for their economic success. The cumulative interaction of outflows (labor, materials, and equipment costs) and inflows (progress payments less retainage) creates a profile with a complex zigzag shape. This could only be modeled by simplification, e.g., as values tabulated at discrete times; averaged S-curves without peaks; or envelopes of all possible constellations. Neither is suited for a fully integrated model that dynamically links schedules with their cash flows for optimization. Therefore, singularity functions, whose components define ranges of behavior between cutoffs, are used to flexibly yet accurately model cash flow profiles and their various payment terms. The new approach augments construction project management toward an integrated planning model and is validated with an example from the literature. Optimization with a simulated annealing algorithm shifts activity positions in a randomized but directed search for maximizing profits.

This paper presents an optimization method for solving a dynamic equipment allocation problem (DEAP) encountered during the implementation of a concrete-faced rockfill dam construction project. In contrast to prior studies, the uncertainties associated with equipment failures have been explicitly considered in the objective function of our mathematical model that maximizes construction throughput. Specifically, our research assumes that the equipment failure time is characterized by a Weibull distribution, which has been justified by a chi-square goodness-of-fit test. A failure probability–work time equation is also used to characterize the relationship between the equipment failure probability and mean time to work. Furthermore, our model considers multiple types of equipment, and each is capable of doing different jobs. The model is confined by the relationship equations, initial conditions, and constraint conditions. Then, the particle swarm optimization (PSO) technique is applied to search for the optimal solution of the DEAP. Finally, the Shuibuya Hydropower Project was used as a real-world example to demonstrate the practicality and efficiency of the optimization method.

The two biggest challenges in the construction industry, low productivity and high injury rates, may be addressed simultaneously through the combination of lean production strategies and traditional safety-analysis tools. This case study used Safety and Lean Integrated Kaizen (SLIK) in a modular housing manufacturing facility by applying one lean production tool, kaizen, and a safety-analysis tool, job safety analysis (JSA). The research team used SLIK with the base-framing crew, and the method consisted of analyzing the current process, determining and implementing process improvements, and analyzing the improved process. The changes resulted in a 16% increase in value-added activities and increased the framing crew’s overall output by 55%. By making quick, low-cost changes that were intended to improve productivity to the station layout and work design, safety and ergonomic hazards, including reduced trip hazards, pinch points, and back strain, were also reduced or eliminated. These results support the hypothesis that productivity and safety can be improved simultaneously through combined lean and safety tools.

In projects with repeating activities (such as multistory buildings, highways, or pipelines consisting of reiterating identical or similar units) and in which the activity unit production rates are characterized by uncertainty or imprecision, fuzzy set theory and the well-established repetitive scheduling method (RSM) can be combined to ensure uninterrupted usage of resources between similar activities in different units. The reason for this approach is that in practice the application of RSM may be hindered by several considerations, for example, repetitive units may be slightly different from each other, the performance of construction crews may vary, and there may be complex resource matching and sharing between activities and work sites. The proposed methodology is termed fuzzy repetitive scheduling method (F-RSM), and it requires a generalization of RSM in which schedules are represented by two- or three-dimensional graphs and whereby the concepts of a control segment and the controlling sequence area are introduced. The resulting methodology addressing the original RSM scheduling problem is presented in this paper.