Journal of Construction Engineering and Management

Adequate compaction of asphalt pavements during their construction is essential to the long-term performance of the pavement. Current quality control techniques determine the quality at a limited number of points and are not indicative of the overall quality of the pavement. In this paper, the intelligent asphalt compaction analyzer (IACA) is used to estimate the density of an asphalt pavement during its construction and thereby determine the overall quality of compaction. A comparison of these estimates with the percent within limits (PWL) calculations based on roadway cores demonstrates that the IACA can be effectively used as a nondestructive quality assurance (QA) tool. Further, since the IACA continuously estimates the density of the asphalt in real time, inadequate compaction can be addressed during the construction, thereby improving the overall quality of pavement. Thus, the IACA can also serve as a valuable quality control (QC) tool during the construction.

Aggregate blending is a problem frequently encountered in the construction industry. In this article, it is shown that robust linear programming can be used to produce solutions protected against noisy data with the same computational complexity of the classic optimization methods for the problem. It is also shown that nonlinear cost functions can be approximated by piecewise linear functions, keeping complexity at a low level. Finally, experimental results are presented. The aim is to understand how robust linear programming solutions compare with those of other methods previously described in the literature and to evaluate the actual quality of the robust solutions.

The results of a quality-control operation performed on the jobsite of a large volume of ready-mix self-consolidating concrete (SCC) are presented. To test the prerequisites of fresh SCC, three tests (slump flow [SF], V-Funnel [VF], and J-Ring [JR]) were prescribed to be performed on every truck. The acceptance condition for the supplied concrete was to meet the specified requirements for all three tests. This procedure seems adequate to derive reliable data about filling ability, resistance to segregation, deformation capacity, viscosity, and passing ability. The correlation between slump-flow and J-ring results suggests that these two tests could be associated by defining a proper reduced J-ring diameter and by checking the difference in height between the concrete inside and outside the ring. In general, it seems that a continuous control should be applied only on specific structures, such as structures with highly congested reinforcement, whereas when the stability of the supplies is achieved, a reduced testing control could be applied for ordinary structures. However, whatever the type of construction, in extreme weather conditions (very hot/cold) special care should be taken, and it could be necessary to increase the number of controls because under these conditions a higher probability of nonconformance to the guidelines was observed.

This research was conducted to assess the effects of temperature segregation in hot-mix asphalt (HMA) paving construction on pavement distress in the early stages of its life cycle. Several paving projects across Nebraska were visited in which sensory devices were used to test how density, moisture content within the asphalt, material surface temperature, internal temperature, wind speed, haul time, and equipment type, contribute to temperature differential. Areas of high temperature differential were identified using an infrared thermal camera. A nonnuclear density device was also used to record how lower temperature asphalt density correlates with a more consistent hot area. The location was marked digitally with a handheld global positioning system (GPS) to locate points of interest for future site revisits to verify research findings. The research findings indicate that among the investigated variables, truck types and density are highly correlated with temperature differential. Additionally, analysis of data from revisits after one or two freeze-thaw seasons shows that higher temperature differential is significantly correlated with premature distress (PD) of paved HMA roads while they are still in new condition. This finding suggests that higher temperature segregation created from paving construction in the zone of freeze-thaw cycles promotes visible surface distress in the very early stage of the pavement life cycle.

The maintenance planning of deteriorating bridges is to find a balance between obtained performance and incurred cost. Because the planning horizon spans tens of years, a certain amount of uncertainty is inherent in forecasting the deteriorating process and the costs and effects of maintenance actions. This paper proposes a multiobjective simulation optimization framework to establish the trade-off among the expected values of life-cycle maintenance cost and of the performance measures. The trade-off information, represented as the Pareto front, gives planners sufficient flexibility to respond to various needs. The optimization is performed by a multiobjective particle swarm optimization (MOPSO) algorithm, while Monte Carlo simulation is used to model the uncertainties. To alleviate the computational burden, the proposed framework is implemented in a parallel computing platform, where three programming paradigms (master-slave, island, and diffusion) are developed to distribute computation across processors and to control interprocessor communication. The validity of the proposed framework, along with the parallel paradigms, is investigated through a practical case. It is shown statistically that the proposed MOPSO algorithm is superior to the well-known nondominating sorting genetic algorithm II as the former can obtain a better Pareto front, whose convergence and diversity are measured together by the hypervolume indicator. Both the island and diffusion paradigms, being loosely synchronous, exhibit high efficiency and good scalability as they achieve superlinear speedups. The island paradigm outperforms the other two in terms of improved solution quality within fixed time.

Delay claims are a common occurrence in construction projects. Many techniques have been developed to assess these delays. The time impact technique is the preferred approach for resolving complex disputes that are related to delays and delay compensation. However, this approach is time-consuming and costly to operate. This research proposes a new approach, similar to the time impact technique, which evaluates delay events in chronological order. The details of the modified time impact analysis (MTIA) method are provided, along with one example to demonstrate its advantages. This method is significantly easier to prepare, and the results generated by this new approach are easier to discuss and examine.

A multilevel safety climate survey was conducted in three Australian organizations in the construction supply chain. A principal components analysis (with varimax rotation) yielded six distinct safety climate factors reflecting aspects of the organizational safety response (OSR), supervisors’ safety response (SSR), and coworkers’ safety response (CSR). Perceptions of top management’s commitment to safety (an aspect of OSR) and supervisors’ safety expectations (an aspect of SSR) were both significantly and inversely correlated with the combined medical treatment and lost time injury rate of workgroups in the analysis. Further, regression analysis revealed that perceptions of supervisors’ safety expectations fully mediated the relationship between perceptions of top management’s commitment to safety and the workgroup injury frequency rate. The results highlight the critical role played by first-level supervisors in acting as the conduit through which organizational safety priorities are communicated to the workforce.

The global expansion of public-private partnerships (PPPs) has generated interest in establishing national PPP units for implementing or analyzing PPPs. Despite the good intentions for establishing such units, results have been mixed. Unless its role is clarified, a national PPP unit cannot be successful because it lacks adequate authority to respond appropriately to the changing environment. However, relevant research in construction journals is too limited to provide policymakers with constructive suggestions. This study aims to improve this situation by aligning a theoretical model with empirical data. The PPP activities can be analyzed as a game between the host government and private promoters trying to maximize their respective payoffs; thus, in accordance with new institutional economics (NIE) theory, a national PPP unit can be considered an endogenous equilibrium outcome of a game. On the basis of this perspective, three game (four consensus) theoretical models are constructed to find equilibriums: a single game for a single authority, repeated games for a single authority, and repeated games for government with multiple subordinate authorities. This study also uses a case study to present the history of PPPs in Taiwan and the evolutionary role of the National PPP Taskforce, Taiwan. National and international data confirm the theoretical model, which indicates that the common role of a national PPP unit is as a trust-creator between the public and private sectors. This pilot study contributes to the theoretical foundation that policymakers need to accelerate the learning process for implementing a PPP. It also provides researchers in the construction field with an NIE methodology for analyzing other governance structures in the construction field.

Ensuring the safety of flaggers, motorists, and workers is the primary consideration for flagging operations during nighttime construction and maintenance. A research study was conducted to evaluate four different types of light equipment—a light tower, 12 V spotlight, 12 V high-intensity discharge (HID) floodlight, and balloon lights—with regards to their level of illumination and uniformity over the flagging area and on the flagger’s body. For each type of equipment, three input variables—lamp output, offset angle, and luminaire height—were varied to create a total of 44 different light equipment configurations. Each configuration was evaluated in terms of illumination, uniformity, and visibility in an urban/suburban setting. The study revealed that a light tower with 2,000 W output, 0° offset angle, and raised to a height of 20 feet was the highest ranked type of equipment. However, when ease of use, mobility, and cost were added as output measures, a 12 V spotlight with 0° offset angle and raised to a height of 10 feet received the highest ranking. Smaller light systems are easy to operate and transport, inexpensive, and more applicable for short-term flagging operations and for operations that need to be relocated frequently. Highly ranked configurations were typically those at 0° offset with luminaires elevated to 10 feet or higher. Configurations with higher luminaire heights and lamp outputs from 250 to 2,000 W may perform better depending on the roadway setting, duration of flagging operation, and amount of artificial background lighting.

Buildability is one of the most important factors influencing labor productivity. A thorough investigation of the literature, however, revealed a dearth of research into its effects on the labor productivity of an integral trade of the in situ reinforced concrete material; namely, rebar installation, especially at the activity levels. Because reinforced concrete columns are among the major encountered activities on construction sites, the objective of this research is to explore primary buildability factors influencing their rebar installation labor productivity. To achieve this objective, a sufficiently large volume of productivity data was collected and analyzed by using multiple and categorical-interaction-regression methods. As a result, the effects of the variability of column sizes, rebar diameter size, reinforcement quantity, and column geometry, are determined and quantified. Although the extent of the size variability and circular geometry show significant negative impacts on the labor efficiency of the operation, the rebar diameter size and quantity of reinforcement installed exhibit positive effects. The results obtained may be used to provide designers and construction managers with feedback on how well the design of this activity considers the requirements of buildability, and the consequences of designers’ decisions on the productivity of the installation operation. Moreover, a set of practical recommendations is presented, which upon implementation can improve the design buildability level of the activity explored and, thus, translate into higher labor productivity and more efficient planning and utilization of operatives.

Since 2008, the Spanish Structural Concrete Code (EHE in Spanish) has generally focused on respecting the environment; as a result, it has become a support tool for designing sustainable concrete structures. The Ministry of Public Works took charge of the initiative and a wide range of professionals and researchers, encompassing various points of view in this sector, carried it through. It is a pioneering initiative, opening up an avenue for the future of sustainable structural design. The purpose of this paper is to summarize the procedure used in drafting the sustainability appendix for the EHE and to present the EHE model for assessing the sustainability of concrete structures. Although the project has had its problems, the model that it produced is very thorough. It includes practically all the main criteria, taking into account the current state of the art and the fact that this was the first time a sustainability assessment technique has been included in a structural code.

In competitive bidding in the United States, the lowest bid is frequently selected to perform the project. However, the lowest bidder may incur significant cost increases through change orders. For project owners to accurately estimate the actual project cost and to predict the bid that is close to the actual project cost, there is a need for new decision aids to analyze the bid patterns. In this paper, two neural network models, a classification model and a general regression model, were used as a method of selecting the bidder that submits the bid closest to the actual project cost. The empirical results suggest that for selected projects these models selected the bids that are closer to the actual project costs than the lowest bid. The outcome of this study addresses the issue of cost overrun, which is a very common problem in the construction industry.

The main difference between the Last Planner production control system developed by Ballard and classical control systems is the way in which projects are controlled and planned. The Last Planner system focuses on controlling production units, workflows, and the quality of the performed work. It also permits the identification of the causes for the noncompletion of planned work and decision making in accordance with the project requirements so that actions are timely and productivity is increased. The objective of this paper is to present the results obtained from implementing the Last Planner system in the construction department of a chemical company. In this department, an information flow problem was detected among its members, in which supervisors lacked knowledge about the work to be performed until the project had been perfectly designed. This problem often led to long delays in the projects. The results from the Last Planner system implementation show that identifying the constraints of the planned work leads to an improvement in the percentage and quality of completed activities.

In refurbishment projects, a great deal of waste from the existing buildings is generated at the demolition stage. By maximizing the amount of waste that is recycled or reused, the environmental impact from the refurbishing works can be minimized. As a solution for environmental impact minimization through maximizing reduction/reuse and recycling of construction debris, the Selective Demolition Method (SMD) has recently been introduced in the construction industry as an alternative to conventional methods. However, there has been a lack of in-depth analysis in terms of productivity, cost efficiency, and environmental impact. This study demonstrates a comparative analysis by quantifying the merits/demerits of the SDM method in a refurbishing residential project. After pilot-testing the SDM method in a real-case project using evaluation tools, including work sampling, a foreman survey, and worker interviews, the results showed that SDM method could lead to positive outcomes compared to the existing demolition method. Although the case study is merely a showcase for quantifying the two methods, the findings may positively support the benefits of the SDM method in terms of cost and environmental issues.

A concession period is a key decision variable in the arrangement of a build-operate-transfer (BOT)-type contract. Recently, an innovative BOT concession model (BOTCcM) was developed to quantitatively determine the value of a concession period. The model could propose an interval for possible negotiations between a host government and a private investor. Nevertheless, this paper identifies a major limitation of this model and proposes an alternative model for improvement. Under a BOT arrangement, the project becomes a property of the host government upon its transfer. The project’s net asset value at the transfer time is usually significantly greater than zero, representing revenue to the host government. This revenue, thus, cannot be ignored. However, this revenue was not considered in the analysis of BOTCcM. This study improves the second critical point in BOTCcM by considering project net asset value at the transfer time. The application of the new model is demonstrated by using the same example case quoted in BOTCcM and shows that a significantly different decision will be made when project net asset value at its transfer time is considered.