Journal of Construction Engineering and Management

Linear schedules continue to hold significant potential for planning and control in construction project management, where work progress of activities is often repetitive in nature. However, linear schedules are limited in graphical comparisons. A slip chart from the aerospace industry, which recorded launch dates on two axes of time, is rediscovered as inspiration for an improved tool. However, whereas its original form could only track points in time, schedule activities must be represented as ranges across time. Therefore, additional theory is needed to extend slip charts toward being able to handle linear schedules. To create such a layout, this research systematically extends its conventions and capabilities. A conversion algorithm for linear schedules is derived. New features are introduced for a comprehensive approach. In particular, buffers that represent minimum and also maximum constraints between activities are investigated and converted. Criticality and float are defined.

Optimizing the layout of facilities on a construction site to minimize the material handling costs has been widely investigated in the literature. An integral part of the objective function utilized in the previously proposed optimization models is the frequency parameter, which generally provides a rough estimate of the frequency of travel between each pair of facilities at a specific stage of the project. The majority of travel frequencies deduced in prior studies have been estimated merely based on past experience and may not be an actual representation of movements within the project studied. There is currently a lack of a systematic approach for estimating travel frequencies, required in site layout planning, based on the information available at early stages of the project. Obtaining a reasonable estimate of the travel frequency matrix requires a realistic evaluation of the material transportation quantities at each construction stage. This necessitates the utilization of information on the progress of different activities and their corresponding material needs during the various stages. This paper presents a framework for obtaining travel frequencies at different construction project phases by taking advantage of the information made available by building information models and project schedules. The estimated frequencies are later embedded as parameters in an optimization model to improve site layout planning. The results of a case study are presented to highlight the capabilities of the proposed framework.

Unprecedented uncertainty in the price of asphalt cement over the last decade has been a source of major concern for state departments of transportation (state DOTs) and highway contractors. This uncertainty may lead to price speculation and inflated bid prices by highway contractors, in order to secure their financial positions against possible rising prices. One of the most common risk-sharing strategies widely used by transportation agencies is price adjustment clauses (PACs) that shift potential upside and downside risk of material prices from contractors to owners. PACs are aimed at eliminating extra risk premiums and therefore reducing contractors’ submitted bid prices. However, the actual effect of offering PACs on submitted bid prices for major asphalt line items has not been empirically studied. The research objective of this paper is to examine the effect of PACs offered by state DOTs on the variations of contractors’ submitted bid prices for major asphalt line items. Data on 841 transportation projects were collected and several potential explanatory variables, such as duration of the project, asphalt cement price index, number of bidders, and eligibility for the PAC program were identified. Multivariate regression analysis was used to create appropriate statistical models that can explain the variations of contractors’ submitted bid prices for five major asphalt line items. The results indicate that eligibility for the PAC program was not a statistically significant variable in most of the models. Thus, no evidence was found to support the statement that offering PACs would reduce the submitted bid prices. It is expected that this work will help capital planners of transportation agencies enhance their understandings about important variables affecting submitted bid prices for highway projects.

Concrete anchors are extensively used in the construction industry. Their applications range from erecting permanent objects such as sign poles, direction signs, lighting poles, and so on, to temporary support structures. Several destructive testing equipment types exist in the industry that can be used to evaluate the load-carrying capacity of concrete anchors. However, no nondestructive testing method has been proposed that can estimate their load-carrying capacity. This study develops a new relationship between the pull-out load-carrying capacity, $P$, of concrete anchors and Schmidt hammer rebound value, $R$. It was observed from experimentation that the load-carrying capacity of the concrete anchors depends on the embedment length, anchor diameter, concrete strength, and anchor alignment. The effect of anchor alignment was also observed during experimentation, and anchors with ill alignment of more than 5% can lead to lower load-carrying capacity. In addition, it is also possible to identify the ill-aligned concrete anchor and anchor bolt installed in poor quality concrete using the test results. A new type of anchor cage is also developed and presented in the research work that can be used to conduct the pull-out testing using the universal testing machine, eradicating the need for separate pull-out testing devices. The 8-, 10-, and 12-mm diameter concrete anchors were studied, keeping constant the embedment length and concrete strength. The pull-out load strength versus rebound value relationship for each diameter anchor is presented with a co-relationship of more than 90%.

The well-known earned value technique measures and evaluates project performance. It uncovers schedule and cost deviations from the baseline plan. However, it is not established to determine acceptable levels of deviations from the baseline. This study applies the Shewhart individuals control charts to overcome this limitation; the charts monitor trends in the project performance behavior and allow them to be detected before the project deviates much from the baseline plan. The study statistically monitors several well-known earned value indexes of a construction project, where the data are autocorrelated and nonnormally distributed. The investigated case showed that the individuals control charts enhance capability of the earned value technique. The authors concluded that implementing the developed tool together with the traditional tools noticeably improves the project controlling scheme and provides more information on project progress. The study extends a previous study in which only independent data were investigated.

The presence of multiskilled workers in a crew can increase the crew’s productivity through reducing inefficiencies and supervision requirements, while also providing on-the-job learning opportunities for single-skilled workers. The effect of the presence of multiskilled workers on the learning rate of workers, which is also a function of skill level and experience, and thus on the crew’s productivity, is especially significant in repetitive construction projects. This paper presents a mathematical model for identifying the optimal combination of single-skilled and multiskilled workers with different levels of experience in the crew to minimize the duration of construction projects by accounting for the overlapping effects of multiskilling, skill level, and learning on the crew’s productivity. The model is applied to an illustrative case project to demonstrate the practicality of the model. The optimum crew compositions for different activities involved in the case project are identified using a solution technique which combines constraint programming (CP), statistical analysis (SA), and a genetic algorithm (GA).

This paper develops a holistic simulation-based approach to determining reasonable strategies to limit the magnitude of ground settlement in shallow tunnel excavation. Simulation models are built to investigate and analyze the impact of different response strategies on the development tunnel-induced movement. A real tunnel case with a shallow buried depth of 5–8 m in the Wuhan metro system in China is utilized to demonstrate the applicability of the developed approach. Results indicate that (1) the simulation technique can be used to model the complex tunnel-soil-ground interaction in a reliable manner and predict the tunnel-induced ground settlement given some grouting strategies are implemented; (2) the optimal control strategy to reduce the tunnel-induced ground settlement should first satisfy the requirement of safety consideration where the ground settlement should be controlled within an allowable range and should then satisfy the cost effective requirement; and (3) the continuous grouting strategy is more suitable to deal with the excessive settlement in case the thickness of covering soil layers is almost equal or less than the tunnel diameter because it can reduce the ground settlement by almost 50%, compared with the situation where no grouting strategies are implemented. The developed approach takes into account both the knowledge of domain experts and computer science techniques and can be used by practitioners in the industry as a decision tool to provide benefits in the development of better alternatives and optimization.

Projects with repeating activities, such as multistory buildings and highways, present unique scheduling challenges. This paper presents the necessary requirements that scheduling systems should address to meet the needs and complexities of repetitive projects in practice. The repetitive scheduling method (RSM) provides a unified scheduling framework that applies to all types of repetitive projects. In RSM, projects are classified as discrete (vertical) or continuous (horizontal or linear) and then as uniform and nonuniform, depending on whether progress is measured using a counting scale or a dominant-attribute scale. RSM modeling elements include three types of activities (line, block, and bar) and 10 types of relationships (links) between activities. $RP2$, a computer program developed by the authors to validate the proposed scheduling approach, is used to develop the production diagrams and tabular reports of the target schedule for a complex of four-story apartment buildings for a low-income housing project. Sufficient detail is provided so that the project and its target schedule can be used to validate future research and to verify other systems.

To enhance concern for the social aspects of sustainability and to delineate the criteria to be considered at each stage of the lifecycle of an infrastructure, this paper aims to determine the relevance of a set of criteria that evaluate social sustainability throughout the lifecycle of a public civil infrastructure. This research presents the results of a case study applying the Delphi method to 24 Chilean experts consulted in a series of three rounds. In addition, binomial statistical tests and Kendall’s coefficient were used to show the convergence of the experts. Thus, it was identified that of 36 initial criteria assessed at each stage of the lifecycle, the consideration of 20 is required at the design stage, 29 at the construction stage, 33 during operation, and 27 at demolition. The most relevant criteria, per lifecycle stage, were Stakeholder Participation (design and demolition stages), External Local Population (design stage), Internal Human Resources (construction and demolition stages), Macro-Social Action of Socioenvironmental Activities (construction stage), and Macro-Social Action of Socioeconomic Activities (operation stage).

Building information modeling (BIM) fundamentally requires the importation of a three-dimensional (3D) model with a series of repository data. Numerous studies have been conducted to clarify the philosophy of BIM and promote its adoption in construction and engineering projects. The primary contributions of this research to the construction engineering and management body of knowledge are the technical review, analysis, and appraisal of various issues concerning the usability of four-dimensional (4D) BIM. The research aims to determine the readiness and development of 4D BIM. A technical literature review was conducted of various BIM software websites, journal articles, brochures, and videos about required 4D elements. A comparative analysis was conducted to compare the technical (TECA) and project-planning functionality (PPFA) aspects of developing 4D models with features provided by available BIM software. This analysis yielded matrices that can be used to guide decision making on which BIM software to invest in. The results reveal that all of the software packages in their way serve the purpose of developing a 4D BIM model.

Ground-penetrating radar (GPR) has proved to be a valuable method for tunneling quality management and evaluation. The research literature includes many successful works addressing the use of this technique with the aim to detect the existence of internal pathologies and anomalies. However, most of them have been carried out on tunnels in operation. In these situations, the identification of inner elements and possible damage has been severely limited due to a shallower rebar mesh that complicates the radar data interpretation process. Therefore, this paper presents the evaluation of an excavated high-speed railway tunnel during the early stages of construction instead of considering a finished one. The purpose of the study was to demonstrate the potential of this method when applied during these first critical phases. The results provided noteworthy information: namely, thickness of the gunite layer, lining voids and delamination, moisture problems, and the presence of reinforcing in the tunnel lining. All this information may be useful for civil engineers when they must make a decision on maintenance and prevention tasks.