Research in Visualization Techniques for Field Construction

Field construction can be planned, monitored, and controlled at two distinct levels: (1)?the activity or schedule level; and (2)?the operation or process level. Graphical three-dimensional (3D) visualization can serve as an effective communication method at both levels. Many research efforts in visualizing construction are rooted in scheduling. They typically involve linking activity-based construction schedules and 3D computer-aided design (CAD) models of facilities to describe discretely evolving construction product visualizations (often referred to as four-dimensional CAD). The focus is on communicating what components are built where and when, with the intention of studying the optimal activity sequence, spatial, and temporal interferences. The construction processes or operations actually involved in building the components are usually implied. A second approach in visualizing construction is rooted in discrete-event simulation that, in addition to visualizing evolving construction products, also concerns the visualization of the operations and processes that are performed in building them. In addition to what is built where and when, the approach communicates who builds it and how by depicting the interaction between involved machines, resources, and materials. This paper introduces the two approaches and describes the differences in concept, form, and content between activity level and operations level construction visualization. An example of a structural steel framing operation is presented to elucidate the comparison. This work was originally published in the proceedings of the 2002 IEEE Winter Simulation Conference. This paper expands on the original work by describing recent advances in both activity and operations level construction visualization.     

Automated Recognition of 3D CAD Objects in Site Laser Scans for Project 3D Status Visualization and Performance Control

This paper presents a new approach that allows automated recognition of three-dimensional (3D) computer-aided design (CAD) objects from 3D site laser scans. This approach provides a robust and efficient means to recognize objects in a scene by integrating planning technologies, such as multidimensional CAD modeling, and field technologies, such as 3D laser scanning. Using such an approach, it would be possible to visualize the 3D status of a project and automate some tasks related to project control. These tasks include 3D progress tracking, productivity tracking, and construction dimensional quality assessment and quality control. This paper provides an overview of the developed approach and demonstrates its performance in object recognition and project 3D status visualization, with data collected from a construction job site.     

Construction Scheduling and Progress Control Using Geographical Information Systems

Traditional scheduling and progress control techniques such as bar charts and the critical path method (CPM) fail to provide information pertaining to the spatial aspects of a construction project. A system called PMS-GIS (Progress Monitoring System with Geographical Information Systems) was developed to represent construction progress not only in terms of a CPM schedule but also in terms of a graphical representation of the construction that is synchronized with the work schedule. In PMS-GIS, the architectural design is executed using a computer-aided drafting (CAD) program (AutoCAD), the work schedule is generated using a project management software (P3), the design and schedule information (including percent complete information) are plugged into a GIS package (ArcViewGIS), and for every update, the system produces a CPM-generated bar chart alongside a 3D rendering of the project marked for progress. The GIS-based system developed in this study helps to effectively communicate the schedule∕progress information to the parties involved in the project, because they will be able to see in detail the spatial aspects of the project alongside the schedule.     

VIRCON: Interactive System for Teaching Construction Management

The focus in this paper is on a system, developed by the writers, called VIRCON (short for VIRtual CONstruction), in which the traditional construction planning is combined with 3D∕4D models of the project. To facilitate current best practices with 3D∕4D models of the project, VIRCON has been implemented using object-oriented programming, client/server configuration, database management information, and CAD systems. The real innovation in the design of VIRCON is associated with the unique scheduling and simulation engine developed to integrate cost planning and scheduling and accommodate integrated cross-impact analysis. VIRCON has been validated by means of student group projects on a course where many of the project management techniques are being taught. The teaching approach conducted with the utilization of VIRCON has shown the way forward in creating a dynamic and interactive learning atmosphere. This paper also outlines the experience gained from teaching construction planning fundamentals by means of the VIRCON system.     

Development of IFC Modeling Extension for Supporting Drawing Information Exchange in the Model-Based Construction Environment

The Industry Foundation Classes (IFC) has been known as a common product model that has interoperability between similar and dissimilar IT systems for the architecture, engineering, construction, and facility management (AEC/FM) industries covering all life cycle phases. Continuous efforts have been undertaken regarding the development of standardized specifications based on the IFC, a product model used in the AEC/FM industries. In accordance, the XM-4 project has been initiated by the Korea Chapter of the International Alliance for Interoperability (IAI) organizations to develop a two-dimensional (2D) extension model for IFC. The XM-4 project aims to add to the IFC2x platform the ability to exchange 2D computer-aided design data within representations of virtual building models, including annotations and styles mainly adapted from the ISO 10303. The focus of this research has been on developing a 2D extension model for the IFC as part of the IAI XM-4 project. This paper provides the scope and rationale of the model extension, major modeling concepts, defined high-level entities and row-level entities, and implementation issues to be considered.     

Feasibility Study of 4D CAD in Commercial Construction

This paper concludes that 4D models are a useful alternative to project scheduling tools like CPM networks and bar charts. They enable more people to understand a schedule quickly and identify potential problems. By developing a 4D model for a commercial construction project, we were able to detect the incompleteness of the original schedule, find inconsistencies in the level of detail among the schedule activities, and discover an impossible schedule sequence. We were also able to anticipate potential time-space conflicts and accessibility problems. The results of the case study show that 4D models are effective in evaluating the executability of a construction schedule. The case study also highlighted the need for improvements to 4D tools. 4D tools should include bar charts, component lists, and annotation tools in their graphical user interface. Automating schedule data preparation and 4D model generation in the design stages of a project can expedite 4D model development and use. Users need to be able to generate 4D models at multiple levels of detail and generate and evaluate alternative scenarios rapidly.     

Resource Optimization Using Combined Simulation and Genetic Algorithms

This paper presents a new approach for resource optimization by combining a flow-chart based simulation tool with a powerful genetic optimization procedure. The proposed approach determines the least costly, and most productive, amount of resources that achieve the highest benefit/cost ratio in individual construction operations. To further incorporate resource optimization into construction planning, various genetic algorithms (GA)-optimized simulation models are integrated with commonly used project management software. Accordingly, these models are activated from within the scheduling software to optimize the plan. The result is a hierarchical work-breakdown-structure tied to GA-optimized simulation models. Various optimization experiments with a prototype system on two case studies revealed its ability to optimize resources within the real-life constraints set in the simulation models. The prototype is easy to use and can be used on large size projects. Based on this research, computer simulation and genetic algorithms can be an effective combination with great potential for improving productivity and saving construction time and cost.     

3D/4D CAD Applicability for Life-Cycle Facility Management

A range of studies have shown that three-dimensional (3D)/four-dimensional (4D) computer-aided design (CAD) has positively impacted the productivity and safety of construction processes. However, its potential impact on the entire life cycle of construction projects has not yet been fully investigated. The opinions of construction professionals have generally been reported on the basis of one-time interviews during several case studies. No statistical approach has yet been adopted to examine the whole spectrum of views about 3D/4D CAD use in construction projects. This study presents a comprehensive statistical analysis about how construction engineers perceive the effectiveness of 3D/4D CAD during various tasks of the construction project life cycle. A focus group interview and a review of the literature produced a total of 35?application areas in which 3D/4D CAD can possibly improve existing construction processes. We identified the areas in which 3D/4D CAD has a high potential to significantly enhance project results by using an importance-performance analysis (IPA) and a questionnaire-based survey involving 165?respondents. These study results are expected to provide new business strategies for 3D/4D CAD by broadening its traditional application realm.     

Challenges in Line-of-Balance Scheduling

The line-of-balance (LOB) method of scheduling is well suited to projects that are composed of activities of a linear and repetitive nature. The objective of this study is to set down the basic principles that can be used in the development of a computerized LOB scheduling system that overcomes the problems associated with existing systems and creates solutions to problems encountered in the implementation of repetitive-unit construction. The challenges associated with LOB scheduling include developing an algorithm that handles project acceleration efficiently and accurately, recognizing time and space dependencies, calculating LOB quantities, dealing with resource and milestone constraints, incorporating the occasional nonlinear and discrete activities, defining a radically new concept of criticalness, including the effect of the learning curve, developing an optimal strategy to reduce project duration by increasing the rate of production of selected activities, performing cost optimization, and improving the visual presentation of LOB diagrams.     

Framework for Providing Customized Data Representations for Effective and Efficient Interaction with Mobile Computing Solutions on Construction Sites

Conceptual representations of information contained in product and process models are often difficult to use for accessing data when performing engineering tasks. This is especially true if project-management information contained in product and process models needs to be made accessible on a mobile computer on construction sites. To make this information accessible, customized conceptual and visual information representations are needed. For the project-management tasks of progress monitoring and creating and administering punch lists, existing approaches that provide access to relevant project information are ineffective and inefficient in transforming information from product and process models into usable representations. As a result, these applications do not always provide information representations that are of the required structure, granularity, and type. In this paper, we describe a navigational model framework, which is an approach that effectively and efficiently creates and manages different views of information contained in product and process models. We validated this framework by implementing a prototype system and testing it through a designed set of experiments. The use cases for these experiments were established in an extensive study on the information and data collection needs on construction sites.     

GA-Based Multicriteria Optimal Model for Construction Scheduling

Resources for construction activities are limited in the real construction world. To avoid the waste and shortage of resources on a construction jobsite, scheduling must include resource allocation. A multicriteria computational optimal scheduling model, which integrates the time∕cost trade-off model, resource-limited model, and resource leveling model, is proposed. A searching technique using genetic algorithms (GAs) is adopted in the model. Furthermore, the nondominated solutions are found by the multiple attribute decision-making method, technique for order preference by similarity to ideal solution. The model can effectively provide the optimal combination of construction durations, resource amounts, minimum direct project costs, and minimum project duration under the constraint of limited resources.     

Fuzzy Logic Approach for Activity Delay Analysis and Schedule Updating

This paper presents a fuzzy logic model that integrates daily site reporting of activity progress and delays, with a schedule updating and forecasting system for construction project monitoring and control. The model developed assists in the analysis of the effects of delays on a project’s completion date and consists of several components: An as-built database integrated with project scheduling; a list of potential causes for delays; a procedure to categorize delays; a method of estimating delay durations utilizing fuzzy logic; a procedure that updates the schedule; and, a procedure that evaluates the effects and likely consequences of delays on activity progress. This model is of relevance to researchers since it makes a contribution in project scheduling by developing a complete approach for handling the uncertainty inherent in schedule updating and activity delay analysis. It also advances the application of fuzzy logic in construction. It is of relevance to construction industry practitioners since it provides them with a useful technique for incorporating as-built data into the schedule, assessing the impact of delays on the schedule, and updating the schedule to reflect the consequences of delays and corrective actions taken. The use of fuzzy logic in the model allows linguistic and subjective assessments to be made, and thereby suits the actual practices commonly used in industry.     

Time-Cost Optimization of Construction Projects with Generalized Activity Constraints

Time-cost analysis is an important element of project scheduling, especially for lengthy and costly construction projects, as it evaluates alternative schedules and establishes an optimum one considering any project completion deadline. Existing methods for time-cost analysis have not adequately considered typical activity and project characteristics, such as generalized precedence relationships between activities, external time constraints, activity planning constraints, and bonuses/penalties for early/delayed project completion that would provide a more realistic representation of actual construction projects. The present work aims to incorporate such characteristics in the analysis and has developed two solution methods, an exact and an approximate one. The exact method utilizes a linear/integer programming model to provide the optimal project time-cost curve and the minimum cost schedule considering all activity time-cost alternatives together. The approximate method performs a progressive project length reduction providing a near-optimal project time-cost curve but it is faster than the exact method as it examines only certain activities at each stage. In addition, it can be easily incorporated in project scheduling software. Evaluation results indicate that both methods can effectively simulate the structure of construction projects, and their application is expected to provide time and cost savings.     

Fuzzy Optimal Model for Resource-Constrained Construction Scheduling

Activity duration is uncertain due to the variation in the outside environment, such as weather, site congestion, productivity level, etc. Furthermore, resources for construction activities are limited in the real construction world so that scheduling must include resource allocation. A new optimal resource-constrained construction scheduling model is proposed in this paper, in which the effects of both uncertain activity duration and resource constraints are taken into account. Fuzzy set theory is used to model the uncertainties of activity duration. A genetic algorithm-based searching technique is adopted to search for the fuzzy optimal project duration under resource constraints. The model can effectively provide the optimal fuzzy profiles of project duration and resource amounts under the constraint of limited resources.     

Object-Oriented Model for Repetitive Construction Scheduling

This paper presents the development of an object-oriented model for scheduling of repetitive construction projects such as high-rise buildings, housing projects, highways, pipeline networks, bridges, tunnels, railways, airport runways, and water and sewer mains. The paper provides an overview of the analysis, design, and implementation stages of the developed object-oriented model. These stages are designed to provide an effective model for scheduling repetitive construction projects and to satisfy practical scheduling requirements. The model incorporates newly developed procedures for resource-driven scheduling of repetitive activities, optimization of repetitive construction scheduling, and integration of repetitive and nonrepetitive scheduling techniques. The model is named LSCHEDULER and is implemented as a windows application that supports user-friendly interface including menus, dialogue boxes, and windows. LSCHEDULER can be applied to perform regular scheduling as well as optimized scheduling. In optimized scheduling, the model can assist in identifying an optimum crew utilization option for each repetitive activity in the project that provides a minimum duration or cost for the scheduled repetitive construction project.     

Critical Path Method with Multiple Calendars

This paper presents the critical path method forward and backward passes with multiple calendars. Multiple calendars are required in many construction projects to effectively represent various project conditions such as work properties, resource availabilities, weather conditions, etc. For this reason, major project management software packages such as P3 and MS-Project provide functions to handle multiple calendars. However, the background theory of handling multiple calendars has not been disclosed, so users of those software packages simply assume without clear knowledge that the time data generated by them are correct. This paper provides how multiple calendars should be handled in scheduling. Applying the theory presented herein, it has been noticed that the P3 operations with two calendars may generate a wrong answer for a start-to-finish with zero lag and inconsistent results in all negative lags when nonworking days are involved. The theory covers all four relationships in the precedence diagramming method with lags of zero, positive, and negative values. This study should be of considerable benefit to the construction industry and academics because it details and advances the theory for scheduling with multiple calendars, which is real scheduling in practice.     

Project Management in Construction: Software Use and Research Directions

This paper focuses on future research and the use of project management software in the construction industry. Data are drawn from an empirical study of project management professionals that yielded 240 replies (35% response rate), 42 of which were from the construction industry. Data were collected on: demographics and work environment, project management software usage patterns, analytical technique usage, data management, and suggestions for future research. The results indicate that construction professionals have different characteristics, needs and preferences, as compared to the overall sample. The study shows that construction professionals are more experienced and educated than the respondents in the overall study, they tend to work on fewer projects with larger numbers of activities, and they are more likely to use Primavera (Primavera, Inc., Bala Cynwyd, Pa.) than Microsoft Project (Microsoft Corp., Redmond, Wash.). Construction respondents are heavy users of critical path analysis for planning and control, resource scheduling for planning, and earned value analysis for control. The number of activities in a typical project and the use of software for all active projects were the key determinants of the usage of specific analytical techniques. These factors are also significant determinants of the types of information entered and updated, although the effect is weaker. Although construction professionals are generally satisfied with the quality of schedules produced by the software, they still expressed a clear interest in future research on resource scheduling∕leveling in general and a net present value option in particular. To maximize the impact on practice, development of new planning and control methods should include their integration into project management software.     

Integrating Construction Process Documentation into Building Information Modeling

The research described in this paper extends the use of building information modeling (BIM) throughout the construction phase of the project life cycle. The owner is a military base that uses three-dimensional (3D) modeling for underground services and the footprints of the buildings. They were interested in determining the feasibility of capturing the construction process and related documents into a similar format. The research was conducted in parallel with traditional methods. The objectives of this project were to create a 3D as-built model, a four-dimensional as-built model, and attach the construction process information to the model for the owner to use after construction. A literature review indicates that BIM application stops at the preconstruction phase with a limited amount of research regarding data collection of the construction process. Significant contributions include practical 3D data collection methods and extending the BIM software products to accommodate construction process documentation. Results indicate that BIM software is not specifically prepared to accomplish these objectives and some modification to procedures as well as software were necessary for the BIM to capture the construction process documentation.