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The traditional network scheduling methods such as the Critical Path Method (CPM), Programme Evaluation Review Technique (PERT), and bar charting are typically not effective for the planning of linear construction projects. Linear scheduling methods, on the other hand, model the progress of repetitive activities in sloping lines and are more effective for linear modelling and analysis. Nonetheless, their use in the construction industry has so far been very limited. Among other reasons for this is the unfamiliarity of construction personnel with these techniques, which plays a major role in hampering their application. This paper introduces a graphically based approach to assist in the linear programming (LP) modelling of linear scheduling analysis. The Planning & Optimization for Linear Operations (POLO) system provides a graphic LP modelling environment in which model formulation can be easily accomplished in a graphic and interactive fashion. Thus, the application of linear scheduling methods can be facilitated. The Isle of Palms Connector Bridge project in Mount Pleasant, South Carolina is used to demonstrate the use of the system.

The purpose of this research project is to reduce the carbon emissions of construction processes by Measuring, Mapping, Modelling and Managing (4Ms) the carbon performance of construction activities. This particular paper presents the research work and major findings in the first two stages: measuring the carbon footprint of construction activities in building projects; and mapping the carbon emissions from construction activities.

A hotel project in South Wales was selected as a case study where the carbon emissions from six categories of construction activities (i.e. management, operations, visitors, deliveries, plant and utilities) were monitored by using carefully designed data collection methods throughout the construction process. Both qualitative and quantitative analysis methods were adopted to distil and map the emissions with construction activities.

This study provides a benchmark for the carbon emissions from construction processes. The results show that construction activities generate more carbon than expected. Of the CO₂ emitted, materials delivery, operational activities and plant operation account for more than 90 per cent of the total emissions. Activities from management, visitors and utilities only contributed 10 per cent of the CO₂ emissions. Carbon emissions from construction processes can be best managed through project planning/scheduling where carbon emissions should be considered as a new criterion for project planning along with time, cost and quality.

There are some limitations with the data collection methods adopted in this study. For example, the fuel/CO₂ emission conversion rate for plant was obtained from online sources. This rate needs to be validated and adjusted on‐site with CO₂ measurement gauges for different equipment. Similarly, the fuel efficiency adjusting rates for vehicles also need to be checked and verified constantly.

The on‐site carbon emission methods, the mapping approaches between the emission and construction activities, and the online system developed in this study (www.constructco2.com/default.aspx) are all embraced by the industry. So far, 76 projects have already subscripted to the online system.

This study developed a set of systematic and feasible approaches to measuring and analysing carbon emissions from construction activities. Unlike the existing studies which mainly focus on recording the carbon emissions on‐site, this research measured the emissions, and mapped the emissions with construction activities. The online system developed could analyse the data collected and support the contractor to decide in which aspects they should make effort to control the carbon emissions.

The 4D CAD model has been accepted for better conceptualizing and comprehending the sequences and spatial constraints in a construction schedule. The purpose of this paper is to identify the deficiencies of the visualization of the 4D CAD model and to propose improvements.

The presentation abilities of the existing 4D CAD model are analyzed and compared with the other conventional methods, namely Gantt chart, network diagram, and the calendar. Four aspects of the visualization are addressed, namely the overview of a schedule, the duration of an activity, the relationship of an activity, and the project progress tracking. The proposed improvements employed different visual properties of 3D CAD objects such as color, line weight, and line type to represent the different activities' performing statuses. A prototype of the 4D CAD model with enhanced visualization was developed on a construction project case.

The model evaluation showed that this development could enhance the visualization of the 4D CAD model and provide a more informative construction schedule.

It is anticipated that the 4D CAD model with these enhancements can substitute for conventional presentation methods of construction schedules.

Construction activities, particularly related to transportation, have a considerable impact on the environment and air quality. This paper aims to present a geographic information systems (GIS) and computer‐aided design (CAD)‐based approach for visualizing, communicating and analysing greenhouse gas (GHG) emissions resulting from construction activities.

A methodology using GIS is developed to graphically represent spatial aspects of construction. The approach adopted involves use of a 3D model developed in CAD environment, which was synchronized with a construction schedule stored in Excel spreadsheets. GIS environment is used to link spatial and scheduling information relevant to GHG emissions from construction activities. A baseline was created to enable effective monitoring of construction emissions.

The presented GIS model has the potential to enhance visualisation of distribution and dynamic variations of GHG emissions and could help stakeholders better analyse and understand how construction activities impact the environment.

This paper presents a novel method of graphically presenting GHG and other hazardous air emissions from construction activities using a GIS‐based approach. The paper presents the result of comparing the 3D surface representation of simulated estimated and actual construction emissions to show the impact of construction activities on the environment to support the engineering analysis and decision‐making process.

Due to its key role in the successful delivery of construction projects, construction productivity is one of the most researched topics in construction domain. While the majority of previous research is focused on the productivity of labor-intensive activities, there is a lack of research on the productivity of equipment-intensive activities. The purpose of this paper is to address this research gap by developing a comprehensive list of factors influencing the productivity of equipment-intensive activities and determining the most influential factors through interview surveys.

A list of 201 factors influencing the productivity of equipment-intensive activities was developed through the review of 287 articles, selected from the ten top-ranked construction journals, by searching for construction productivity in the articles’ titles, abstracts or keywords. Next, the most influential factors were determined by conducting interview surveys with 35 construction experts. To ensure that the interviewees were aware of the research objectives and the distinction between labor- and equipment-intensive activities, an information session was held prior to conducting the surveys, and the surveys were conducted in interview format to allow for clarification and discussion throughout the process.

Project management respondents identified foreman-, safety- and crew-related factors as the categories with the most influence on productivity; tradespeople respondents identified foreman-, equipment- and crew-related factors as the most influential categories. In total, 14 factors were identified, for which there was a significant difference between the perspectives of project management and tradespeople regarding the factors’ influence on productivity.

This paper provides a comprehensive list of factors influencing the productivity of equipment-intensive activities. It identifies the most influential factors through an interview survey of 35 construction experts, who are familiar with the challenges of equipment-intensive activities based on their experience with such activities in the industrial construction sector of Alberta, Canada. Additionally, the differences between the factors that influence the productivity of labor- and equipment-intensive activities are discussed by comparing the findings of this paper with previous research focused on labor intensive activities.

The purpose of the study is to explore the dominant ideas in research on the management of time in construction. The focus of research has been to improve techniques for optimising the timing and sequence of activities.

A critical review of research on construction time management, challenging the typical focus. We examine the assumptions different authors make, underline the limitations of the dominant research approaches and examine the prospects for developing a new approach to researching these issues.

The dominant approach in literature focuses on unique activity traits in construction planning and measurable patterns between time-related variables. This assumes that time in construction can be managed by changing the way activities are calculated. These approaches have not been correlated with improvement in performance. Social practice theory may help to explain how programmes figure as one of many objects used during construction.

The focus is on reviewing indicative literature from key journals in construction management. The implication is that research is needed about how such documents are used in practice, which goes further than optimising plans in theory.

Future research could focus on understanding the context of construction planning practice and shift the debate from a focus on optimisation to practice.

An interpretivist approach with a focus on how tools such as planning documents are used on site. Social practice theory may provide a clearer explanation of the place of construction planning within the practice of construction management. This could provide solutions that deal effectively with stakeholder expectations around timely completion of construction projects.

This paper proposes to apply the lean philosophy principle of minimizing or eliminating non-value adding activities combined with 4D building information modeling (BIM) simulations to reduce transportation waste in construction production processes.

This study adopts design science research (DSR) because of its prescriptive character to produce innovative constructions (artifacts) to solve real-world problems. The artifact proposed is a set of constructs for evaluating the utility of 4D BIM simulations for transportation waste reduction. The authors performed two learning cycles using empirical studies in projects A, B and C. The construction process of cast-in-place (CIP) reinforcement concrete (RC) was selected to demonstrate and evaluate 4D BIM's utility. The empirical studies focused on understanding the current transportation waste, collecting actual performance data during job site visits and demonstrating the usage of 4D BIM.

In the first cycle, 4D BIM successfully allowed users to understand the CIP-RC process's transportation activities, which were modeled. In the second cycle, 4D BIM enabled better decision-making processes concerning the definitions of strategies for placing reusable formworks for CIP concrete walls by planning transportation activities.

In Cycle 2, three different scenarios were simulated to identify the most suitable formwork assembly planning, and the results were compared to the real situations identified during the job site visits. The scenario chosen demonstrated that the 4D BIM simulation yielded an 18.75% cycle time reduction. In addition, the simulation contributed to a decrease in transportation waste that was previously identified.

The original contribution of this paper is the use of 4D BIM simulation for managing non-value adding activities to reduce transportation waste. The utility of 4D BIM for the reduction of those conflicts considered three constructs: (1) the capacity to improve transportation activity efficiency, (2) the capacity to improve construction production efficiency and (3) the capacity to reduce transportation waste consequences.

Recognizing every worker's working status instead of only describing the existing construction activities in static images or videos as most computer vision-based approaches do; identifying workers and their activities simultaneously; establishing a connection between workers and their behaviors.

Taking a reinforcement processing area as a research case, a new method for recognizing each different worker's activity through the position relationship of objects detected by Faster R-CNN is proposed. Firstly, based on four workers and four kinds of high-frequency activities, a Faster R-CNN model is trained. Then, by inputting the video into the model, with the coordinate of the boxes at each moment, the status of each worker can be judged.

The Faster R-CNN detector shows a satisfying performance with an mAP of 0.9654; with the detected boxes, a connection between the workers and activities is established; Through this connection, the average accuracy of activity recognition reached 0.92; with the proposed method, the labor consumption of each worker can be viewed more intuitively on the visualization graphics.

With this proposed method, the visualization graphics generated will help managers to evaluate the labor consumption of each worker more intuitively. Furthermore, human resources can be allocated more efficiently according to the information obtained. It is especially suitable for some small construction scenarios, in which the recognition model can work for a long time after it is established. This is potentially beneficial for the healthy operation of the entire project, and can also have a positive indirect impact on structural health and safety.

Previous research regarding shaping factors and major causes behind accidents in the construction field is reviewed. In particular, a hypothetical model is established to correlate activity time, cost and safety in the context of construction activity acceleration planning. Two demonstration cases are presented to illustrate the proposed theoretical model in the context of critical activity expedition planning. Further, a third case uses a 100-activity project to perform the global level total project time and cost analysis, identifying specific activity acceleration plans that would materialize the shortened total project time at the lowest total project cost.

This research proposes a safety-centric application framework to guide construction acceleration planning at both activity and project levels while taking sufficient preventive measures against safety hazards and accidents. As planning construction acceleration by factoring in safety constraints inevitably drives up cost, it is imperative to control increases in activity costs at the local level in connection with schedule acceleration planning while at the same time not compromising on safety. This research also addresses this critical question through performing global level total project time and cost analysis.

An application framework is proposed for guiding a planner through identifying accident shaping factors, obeying schedule acceleration rules and accounting for safety-related costs in attempts to mitigate hazardous situations on-site at both activity level (local) and project level (global), resulting in (1) minimizing the increase of total project cost in schedule acceleration while at the same time not compromising on safety at individual activities; (2) producing specific execution plans on each individual activity in terms of the amount of time to crash and the associated activity cost.

This study is original in developing theories and methods for evaluating the impact of safety constraints upon construction time and cost in activity acceleration planning and project time-cost analysis. The research fills a gap in knowledge in terms of how to factor in sufficient safety constraints while achieving project time and cost objectives on construction acceleration planning at both activity and project levels.

Achieving project objectives in constructionprojects such as time, cost and quality is a challenging task. Minimizing project cost often results in additional project duration and might jeopardize quality, and minimizing project duration often results in additional cost and might jeopardize quality. Also, increasing construction quality often results in additional cost and time. The purpose of this paper is to identify and analyze trade-offs among the project objectives of time, cost and quality.

The optimization model adopted a quantitative research method and is developed in two main steps formulation step that focuses on identifying model decision variables and formulating objective functions, and implementation step that executes the model computations using multi-objective optimization of Non-Dominated Sorting Genetic Algorithms to identify the aforementioned trade-offs, and codes the model using python. The model performance is verified and tested using a case study of construction project consisting of 20 activities.

The model was able to show practical and needed value for construction managers by identifying various trade-off solutions between the project objectives of time, cost and quality. For example, the model was able to identify the shortest project duration at 84 days while keeping cost under $440,000 and quality higher than 85 percent. However, with an additional budget of $20,000 (4.5 percent increase), the quality can be increased to 0.935 (8.5 percent improvement).

The present research work is limited to project objectives of time, cost and quality. Future expansion of the model will focus on additional project objectives such as safety and sustainability. Furthermore, new optimization models can be developed for construction projects with repetitive nature such as roads, tunnels and high rise buildings.

The present model advances existing research in planning construction projects efficiently and achieving important project objectives. On the practical side, the optimization model will support the construction industry by allowing construction managers to identify the highest quality to deliver a construction project within specified budget and duration, lowest cost for specified duration and quality or shortest duration for specified budget and quality.

The present model introduces new and innovative method of increasing working hours per day and number of working days per shift while analyzing labor working efficiency and overtime rate to identify optimal trade-offs among important project objectives of time, cost and quality.