Automation in Construction

The demand for the concrete products is seasonal and huge stock is built in winter for dispatch in summer. Stockyards in the precast concrete products industry are experiencing space congestion, and long vehicle waiting times for both the storage and retrieval of concrete products due to lack of a proper methodology to manage stockyard layouts and their operations. The paper describes an ongoing research that addresses the stockyard layout management problem through the development of an integrated simulation and visualisation model. The paper focuses on the development of the visualisation and simulation element of the stockyard management system "SimStock". The simulation model integrates production and forecast schedules, evaluates "what-if" scenarios with different layouts, products allocation to storage locations and order picking policies. The output of the simulation model is recorded in a database. The visualisation model was developed through integrating AutoCAD2000 with the database of the simulation model such that the simulated layouts can be studied in greater details and validated in a simpler manner. The visualisation module is used to assist managers in designing stock layouts and visualise the simulation process in 2D (and 3D) perspectives, and manage real time implementation of proposed stockyard solutions

Even before Louis Sullivan coined the phrase `Form Follows Function,' architectural researchers have sought, to no avail, a causal relationship between these two primary constituents of the building enterprise. This paper attempts to explain why this quest has been futile, and proposes a performance-based design paradigm, instead of the prevailing process-based paradigms. It suggests that the driving force behind any design activity is the desire to achieve a qualitative solution for a particular combination of form and function in a specific context. Furthermore, it suggests that quality can only be determined by a multi-criteria, multi-disciplinary performance evaluation, which comprises a weighted sum of several satisfaction/behavior functions. The paper develops a performance-based design methodology and demonstrates its application in an experimental, knowledge-based CAD system.

This paper presents a process-based quality management information framework to improve the productivity of the quality system (QS) process based on the new version of ISO 9000 approved in 2000. To apply the new standard into construction projects, this research built a group of information models and developed a process-based quality management information system, called ISO 9000 quality management information system (QMIS). The system integrates scheduling with the QS process covering inspection and testing, nonconformance reporting, and corrective action during the construction phase. ISO 9000 QMIS was validated successfully through a pilot test, and the results and feedback are discussed.

A likely system architecture for future information integration within the building industry will be an integrated backend database. The effective representation of design knowledge is one key element in this strategy. Another is support formodular evolution and change of the database structure as a design evolves. The Engineering Data Model (EDM) provides a strong foundation for defining the semantics of building design information and for suppoting extensibility. Here, we give an overview of the EDM research. We present our view of modularity and the integration of knowledge in a computerized design environment.

This study has developed a product model based on ISO 10303 to overcome problems such as data loss during transferring and sharing project data. The developed product model electronically represents three-dimensional shapes, structural analysis and structural design information of steel bridges. The product model for semantic description of a steel bridge is employed as data structure of an integrated database management system (DBMS) by which steel bridge information can be managed and operated. The DBMS can be made to release restraints such as each different location and heterogeneous computer environments. End-users may be able to freely access steel bridge information of the DBMS on the network. This study also presents a framework for practical management of steel bridge information generated from existing tools by using open standards and web technology. An integrated computer environment can be built by applying this framework composed of product model, data repository, application modules, and programming interfaces to civil engineering fields.

The purpose of this paper is to present drawing production methods based on the difference between 2D- and 3D-oriented approaches. This study emphasizes the comparison of the two approaches in data production, updating and analysis. Architectural CAD drawings are outputted from design information through a computational interface. A drawing production model (P) can be represented by a database (DB) and an interface (I). The input interface is the input or update method between users and application systems. The output interface is the method of presenting architecture drawings like plans, elevations, sections and details based on input data. Under the constraints of a predefined data structure, the computational interface determines the efficiency and characteristics of input and output data. Drawing production methods can be classified into three types: segregating drawing files, applying reference files and constructing a virtual building model. These types come with different interfaces: 2D drafting has the same input and output interface, whereas constructing a 3D model is achieved using a different interface. A digital building model is defined as the electronic information of a whole building which is assembled by components with attributes. 2D- and 3D-oriented drawing methods are compared, based on items such as the required preparation before drafting, consistency of plans, elevations and sections, ease of modification, drafting efficiency, number of persons involved, and analysis potential.

3D virtual worlds facilitate a level of communication and collaboration not readily available in conventional CAD systems. The integration of virtual worlds and CAD systems using a common data model can make a significant impact on synchronous collaboration and real-time multiuser multidisciplinary modification of building data. By using agents, the integration of 3D virtual worlds and CAD systems can go beyond that of passive data transfer. With sensors and effectors, each agent can interact with its environment by responding to changes in the CAD system or 3D virtual world, which can take the form of an update to the geometry or as a recommendation to change nongeometric information or to propagate changes to other parts of the design. The reasoning process for each agent can vary from a reflexive behaviour, in which the agent responds directly to the sensor data to a reflective behaviour in which the agents reasons about its goals and alternatives before making a change to the environment. We demonstrate this approach using ArchiCAD and Active Worlds as the CAD system and the virtual world platform. An EDM database is used as the central repository for storing the representation of the relevant data model. A multiagent system is developed to connect the virtual world to this database to allow active data sharing. This agent approach can be extended to the integration of other applications and data models.

This paper describes a case study investigating the use of 3D laser scanning and global position system (GPS) to acquire landslide data and to compute earthwork volume. 3D laser scanning, which is just samples the earth's surface in some fixed pattern, is not capable of pointing to particular objects or object features directly in exact global orientation. To obtain global geographic coordinates, a GPS is introduced for use. This study including a brief description of the technology, the measurement method, the operation, and the results of the case study is presented. Compared to conventional methods such as triangulation, field and office time of operation was reduced using laser scanning and GPS. Applications where safety may be an issue, such as providing accurate measurements on a landslide or debris flow area, will benefit the most from the strengths of this technology.

Techniques to rapidly model local spaces, using 3D range data, can enable implementation of: (1) real-time obstacle avoidance for improved safety, (2) advanced automated equipment control modes, and (3) as-built data acquisition for improved quantity tracking, engineering, and project control systems. The objective of the research reported here was to develop rapid local spatial modeling tools. Algorithms for fitting sparse range point clouds to geometric primitives such as spheres, cylinders, and cuboids have been developed as well as methods for merging primitives into assemblies. Results of experiments are presented and practical usage and limitations are discussed.

Where educational validity is concerned, a school of engineering can reasonably be expected to constantly update computational resources in frequent use in the professions. Virtual reality (VR) technology could be applied as a complement to three-dimensional (3D) modelling, leading to better communication whether in vocational training, in education or in professional practice. Techniques of 3D modelling and VR were applied to the development of models related to the construction process. The 3D models created to support rehabilitation design emerge as an important tool for the monitoring of anomalies in structures and to assist decisions based on the visual analyses of alternative solutions. The VR model created to help the management of lighting systems in buildings allows the visual and interactive transmission of information related to the physical behaviour of the elements, defined as a function of the time variable. Didactic interactive models showing construction works were also developed. These applications allow the visual simulation of the physical progression of each type of work and also assist in the study of the necessary equipment needed and how it functions on site. The introduction of CAD and VR techniques in school is helpful to students in order to prepare them to consider these technologies as important supports, later in their professional practice.

Automated detection and modeling of 3D objects located in a construction work environment is critical for autonomous heavy equipment operation. Such automation allows for accurate, efficient, and autonomous operation of heavy equipment in a broad range of construction tasks by providing interactive background information. This paper proposes a 3D object detection and modeling system which utilizes range data obtained by 3D range imaging camera to generate 3D object models with an acceptable level of accuracy in a few seconds. The proposed system consists of four steps: data acquisition, pre-processing, object segmentation, and 3D model generation. The system was tested on the modeling of different classes of construction objects on actual construction sites. The results show that the proposed 3D object detection and modeling system achieves a good balance between speed and accuracy, and hence could be used to enhance efficiency and productivity in the autonomous operation of heavy equipment.

Effective monitoring of personnel movements, material locations, and construction equipment has always been a topic of concern in construction management. Radio Frequency Identification (RFID) technology has been proven to increase efficiency for staff and materials management. The objective of this study is to develop a Three-Dimensional (3D) location sensing algorithm using RFID technology to analyze the possible location of objects. To achieve this goal, this research first establishes an indoor wireless sensing network to collect Received Signal Strength Indication (RSSI). The distance between the antenna and target tag is calculated based on RSSI. The gradient decent method is then used to calculate the location of the electronic tag. The feasibility of this 3D positioning algorithm is verified using a real case. The experiment proves that the location sensing algorithm established in this study can gradually approach the actual location of the target tag. This research is one of the first studies for 3D location sensing with RFID application in the construction industry. The proposed RFID 3D sensing algorithm can be used to assist construction managers in locating the positions of relevant personnel, equipment, apparatus and materials, enhancing management efficiency and safety.

3D modeling and computer simulations provide new ways for architecture students to study the relationship between the design and construction of buildings. Digital media help to integrate and expand the content of courses in drafting, construction and design. This paper describes computer-based exercises that intensify the student's experience of construction in several courses from sophomore to senior level. The courses integrate content from drafting and design communication, construction, CAD, and design.Several techniques are used to strengthen students' awareness and ability in construction. These include:•Virtual design–build projects in which students construct 3D CAD models that include all elements that are used in construction.•Virtual office in which several students must collaborate under the supervision of a student acting as project architect to create a 3D CAD model and design development documents.•Virtual sub-contracting in which each student builds a trade specific 3D CAD model of a building and all of the trade specific models must be combined into a single model.•Construction simulations (4D CAD) in which students build 3D CAD models showing all components and then animate them to illustrate the assembly process.•Cost estimating using spreadsheets.These techniques are applied and reapplied at several points in the curriculum in both technical laboratory courses and design studios.This paper compares virtual construction methods to physical design–build projects and provides our pedagogical arguments for the use of digital media for understanding construction.

This paper explores the interdisciplinary use of 3D object models in design team practice by applying a holistic research approach. Based on a qualitative case-study of the ongoing and prestigious building project New Icelandic National Concert- and Congress Center (CCC-project) in Reykjavik, the paper presents five stories about different challenging or beneficial situations from using 3D object models. The implementation of such technology was connected to strategies and guidelines formulated in the Danish public–private R&D program “Digital Construction”. A descriptive and multi-level framework for exploring the ICT impact on the architectural design process has been applied to the analyzing and organizing of the case-study data. A narrative story-telling technique is used to capture and communicate the complex case-study findings into five design team stories, which each highlight central issues embedded in the relation between the design team processes and the technology. The following situations are explored: developing complex geometry, achieving shared understanding, handling the painful processes of change, formalizing processes within a dynamic design environment and handling the interface between design and production. The stories show that a number of the challenges perceived by the design team actors were linked to the nature of the architectural design process, particularly to its “hard-to-grasp”, iterative and intuitive features. The stories indicate that the interdisciplinary use of 3D object models is affected by the many interdependencies, relations and interfaces embedded in the highly complex and partly unpredictable real world practice. A future challenge would be to better understand, master and balance these relationships — across multiple levels, processes and activities. The presented holistic research approach and the related findings contribute to research which attempts to embrace the complexity of real-life problems and to gain a more comprehensive understanding of real-life problems.

The presented research investigated generic and scalable techniques to accurately represent 3D motion paths in dynamic animations of operations simulated using Discrete-Event Simulation. The work designed and implemented methods that can be used to 1) define and manipulate arbitrarily-shaped trajectories to represent accurate 3D motion paths of virtual simulation objects, and 2) compute the precise three-dimensional spatial configuration of virtual simulation objects when they travel on defined paths. In order to address the problem of describing the accurate motion of simulation objects on realistic paths, the research investigated the requirements of two key technologies: 1) A mathematical representation for defining arbitrarily complex curves that can, by manipulating only high-level interaction parameters, be locally and/or globally edited to describe a realistic motion trajectory, and 2) A geometric basis to guide the computation of a simulation object's correct 3D orientation as it travels on an arbitrarily uneven virtual terrain surface. In order to achieve the first objective, the research investigated a technique of producing a general class of interpolating cubic splines whose shape can be locally or globally controlled by modifying three high-level control parameters. In addition, by implementing an innovative virtual terrain-following algorithm, a computation scheme was designed that correctly calculates and portrays the orientation of simulation objects along all three axes (yaw, pitch, and roll) as they travel inside animated 3D virtual worlds. The designed animation methods were implemented in a software tool called PathFinder that integrates as an add-on with the VITASCOPE visualization system.

The complicated nature of interior construction works makes the detailed progress monitoring challenging. Current interior construction progress monitoring methods involve submission of periodic reports and are constrained by their reliance on manually intensive processes and limited support for recording visual information. Recent advances in image-based visualization techniques enable reporting construction progress using interactive and visual approaches. However, analyzing significant amounts of as-built construction photographs requires sophisticated techniques. To overcome limitations of existing approaches, this research focuses on visualization and computer vision techniques to monitor detailed interior construction progress using an object-based approach. As-planned 3D models from Building Information Modeling (BIM) and as-built photographs are visualized and compared in a walk-through model. Within such an environment, the as-built interior construction objects are decomposed to automatically generate the status of construction progress. This object-based approach introduces an advanced model that enables the user to have a realistic understanding of the interior construction progress.

Until recently, visualization of 3D models required computational resources available only on desktop computers in office environments. With the advance of technology, it is now possible to visualize substantial 3D models on mobile handheld computers in the field. This paper discusses some of the current technology, discusses the use of the Virtual Reality Modeling Language on mobile handheld computers, shows several examples of 3D structural steelwork models visualized on a mobile handheld computer, and identifies some of the limitations imposed by current technology.

Aiming at the rule-based recognition system for architectural structure drawings (ASDs), this paper presents a sample-based method that will automatically extract the geometric features of architectural objects and convert the features into recognition rules. When users designate the first sample of one type of objects, this method automatically analyzes and extracts the features useful for drawing recognition. Aided by a little interactive operation, recognition rules for this type of objects are generated. When a new sample of one object is designated through automatically comparing the new features and the old, this method analyzes and modifies the features of this object, then generates new rules. Along with new object types or new representations of old types are processed, rules of the recognition system are perfected continuously without modifying the program. This method can bring to the drawing recognition system higher self-adaptability and practicability.

Nowadays the rapid advances in digital imaging sensors and scanners, computer modeling and multimedia technologies, as well as the availability of many powerful graphics PCs and workstations make new methods for digital documentation of buildings feasible. Digital documentation with 3-d modeling functionality is a new term in architecture and engineering, supporting documentation extensions for e-learning (pedagogically functionality) and meta-documentation (vastness data and meta-data for historical living systems functionality)· which are introduced to literature for the first time within this paper. In particular, such a methodology must be able to derive pictorial, geometric, spatial, topological, learning and semantic information from the target architectural object (historical building, monument), in such a way that it can be directly used for e-learning and meta-documentation purposes regarding the history, the architecture, the structure and the temporal (time-based) 3-d geometry of the projected object. A practical project is used to demonstrate the functionality and the performance of the proposed methodology. In particular, the processing steps from image acquisition to the 3-d geometric and semantic description of the St. Achilleios basilica, lake Prespes, Northern Greece in a CAAD model are presented. Also, emphasis is placed on introducing the new terms e-learning and meta-documentation functionality as functionality extensions to proposed digital documentation method. Finally, comparisons of cost and relative disadvantages of other methods of documentation are examined, and for documentation and learning purposes related to 3-d modeling, a comparison of the results for images taken by a digital solid-state sensor camera and a metric film-based one is carried out and presented.

Capturing and modelling 3D information of the built environment is a big challenge. A number of techniques and technologies are now in use. These include EDM, GPS, and photogrammetric application and also remote sensing applications. In this paper, we discussed 3D laser scanning technology, which can acquire high density point data in an accurate, fast way. Besides, the scanner can digitize all the 3D information concerned with a real world object such as buildings, trees and terrain down to millimetre detail Therefore, it can provide benefits for refurbishment process in regeneration in the Built Environment.A series of scans externally and internally allows an accurate 3D model of the building to be produced. This model can be sliced through different planes to produce accurate 2D plans and elevations. This novel technology improves the efficiency and quality of construction projects such as maintenance of buildings or group of building that are going to be renovated for new services in the Built Environment. In addition, the laser scanner technology can be used in integration with differential GPS for terrain modelling for the analysis and inspection of terrain structure accurately.In this paper, two case studies are introduced to demonstrate the use of laser scanner technology in Built Environment. These case studies are the Jactin House Building in East Manchester and the Peel building in the campus of University Salford. Through these case studies, while use of laser scanners are explained, the integration of it with various technologies and systems are also explored for professionals in both Built and Natural Environment.

Autonomous Guided Vehicles (AGVs) are a way of life in manufacturing where navigation can be done in a structured environment. Construclion is an unstructured environment and requires a different type of navigation system to deal with three dimensional control and rough terrain. This paper provides a review of navigation systems that utilize dead-reckoning in conjunction with absolute referencing systems such as beacon-based systems, and vision and mapping based system. The use of a real-time laser based technology is demonstrated as a new form of navigation. This, technology does not rely on dead reckoning. The paper outlines the issues and strategies in guiding an autonomous vehicle utilizing only the laser-based positioning system. Algorithms were developed to provide real-time control of the AGV. The laser based positioning system is unique in that it provides three dimensional position data with five updates per second. No other system can provide this level of performance. This allows for control of end effectors and autonomous vehicles in complex and unstructured three dimensional environments. The use of this new type of navigation makes possible the automation of large complex assemblies in rough terrain such as construction.

This case study presents the World Wide Web as an appropriate medium for architectural teaching. The prototypical tool VRSolar uses simple programming and existing Web resources to help in the teaching of topics related to the movement of the sun and its effects on the built environment. Using JavaScript, this tool is capable of generating real time Web content in html and VRML based on user input. Accessible on the Web from within a standard Web browser, this tool calculates the solar positions of any location on earth and indicates the solar access to a given site in the form of a three-dimensional Web page, which the user can view, navigate through, and animate.

The use of 3D imaging systems (e.g., laser scanners) in construction has grown significantly in the past decade. Range images acquired with such systems often require registration. This paper describes an automatic method to rapidly locate spheres and perform a registration based on three pairs of matching points (centers of fitted spheres) in two range images. The proposed method is directly applicable for regularly gridded datasets obtained with instruments that are typically used for construction applications and whose maximum ranges are greater than 50 m. A lab was scanned from two locations at three different scan densities. Four spheres were located in the lab, and the total number of points hitting the four spheres was a small fraction (< 0.01%) of all the points in the dataset. At the highest scan density, the registration of two datasets with 6.4 × 106 and 3.4 × 106 points is obtained in less than 30 s. At the medium scan density, two range images with 1.6 × 106 and 0.8 × 106 points can be registered in less than 2 s.

Virtual reality has the potential to improve visualisation of building design and construction, but its implementation in the industry has yet to reach maturity. Present day translation of building data to virtual reality is often unidirectional and unsatisfactory. Three different approaches to the creation of models are identified and described in this paper. Consideration is given to the potential of both advances in computer-aided design and the emerging standards for data exchange to facilitate an integrated use of virtual reality. Commonalities and differences between computer-aided design and virtual reality packages are reviewed, and trials of current system, are described. The trials have been conducted to explore the technical issues related to the integrated use of CAD and virtual environments within the house building sector of the construction industry and to investigate the practical use of the new technology.

Construction progress monitoring has been recognized as one of the key elements that lead to the success of a construction project. By performing construction progress monitoring, corrective measures and other appropriate actions can be taken in a timely manner, thereby enabling the actual performance to be as close as possible to the desired outcome even if the construction performance significantly deviates from the original plan. However, current methods of data acquisition and its use in construction progress monitoring have tended to be manual and time consuming. This paper proposes an efficient, automated 3D structural component recognition and modeling method that employs color and 3D data acquired from a stereo vision system for use in construction progress monitoring. An outdoor experiment was performed on an actual construction site to demonstrate the applicability of the method to 3D modeling of such environments, and the results indicate that the proposed method can be beneficial for construction progress monitoring.

Buildings are complex products containing relatively large numbers of distinct parts that are collected in multiple assemblies for different design, analysis and production purposes. Modeling buildings in fully parametric 3D computer-aided design (CAD) systems offers numerous benefits in terms of productivity, the ability to rapidly generate design alternatives at different levels and elimination of errors that result from the disparity between different drawings in current practice. However, full realization of these benefits requires specialized functionality, including top-down modeling, objects with functional behavior, the ability to embed contextual design intent, automation of layout and detailing and appropriate management of similar objects. An effective system must provide such functionality while maintaining adequate response times. The requirements, features and performance have been examined as part of specification of a new 3D parametric CAD platform for the North American Precast Concrete Software Consortium (PCSC). They are described and discussed after a review of solid and parametric modeling, with examples from the domain of precast concrete construction.

Most high-rise building construction projects rely on tower cranes to perform lifting and hoisting activities. In practice, tower cranes are managed based on demand, urgency, and prioritized work tasks that must be performed within a set period of time in the field. As a computer tool, simulation has proved to be effective in modeling complex construction operations and can be a substantial help in aiding practitioners in construction planning. However, the use of simulation has fallen far below its maximum potential due to a lack of appropriate support tools which would allow construction managers to use simulation tools for themselves. Special purpose simulation (SPS) and 3D visualization of simulated operations are two potential means that enable domain experts, who are knowledgeable in give domains, but not familiar with simulation, to easily model an operation within their domain and analyze the simulation results. This paper presents a practical methodology for integrating 3D visualization with SPS for tower crane operation. An integrated system was built in a 3D Studio MAX environment and tested in the construction of the new civil and environmental engineering building at the University of Alberta. This paper demonstrates that 3D visualization is helpful in the verification and validation of simulation results, and can effectively communicate the essence of a simulated operation, thus improving the accessibility of simulation as a decision making aid.

Automated and robust retrieval of three-dimensional (3D) Computer-Aided Design (CAD) objects from laser scanned data would have many potentially valuable applications in construction engineering and management. For example, it would enable automated progress assessment for effortless productivity tracking, automated 3D image database searching for forensic and legal analysis, and real-time local modeling for automated equipment control and safety. After reviewing and analyzing previous research in the field of automated object recognition, this paper presents a new approach for robust automated recognition/retrieval of 3D CAD objects in range point clouds in the Architectural/Engineering/Construction & Facility Management (AEC-FM) context. This approach is validated in laboratory experiments. A first experiment demonstrates that this new approach can efficiently and robustly automatically retrieve 3D CAD model objects in construction laser scanned data. A second experiment demonstrates how this approach can be used for efficiently assessing construction progress. The results presented here are preliminary but conclusive for proof of concept. More extensive field experiments in this and other application areas will follow to characterize performance trade-offs in practice.

In construction planning practice, increasingly 4D CAD system are applied for construction analysis and communication. Normally the planning expert is responsible for relating building components to construction activities. In this article we describe a method for automated generation of the construction planning. An algorithm is presented that derives the construction order from a solid model of the building. Experiences from a pilot study illustrate the differences between the real planning and the generated planning, and they show the limitations of the current implementation. Finally an outlook is presented on a more advanced planning system that includes contractor's specific knowledge for more accurate results.

Project teams face ever increasing pressure to deliver projects as quickly as possible. To meet these demands, contractors are faced with the need to explore various construction strategies in order to meet delivery dates, and to assure themselves as to the achievability and quality of a schedule. Various visual representations of a project's schedule and associated information combined with visual representations of the project in progress, i.e. 4D CAD, can assist with these tasks of identifying effective construction strategies for shortening project duration, assessing their workability, and judging schedule quality. Such visual representations aid communication amongst project staff and facilitate brain-storming, and, implemented well they can provide clear, fast, and multi-dimensional feedback to the project team. In this paper, we describe aspects of our work which is directed at formulating a dynamic visualization environment that links 3D CAD, a generalization of traditional CPM which embraces linear scheduling, dual product representations (scheduling and CAD system) and their mapping onto each other, and schedule and CAD graphics in a manner which facilitates the relatively rapid exploration of alternative construction method and scheduling strategies for large scale linear projects (e.g. high-rise buildings, bridges, etc.). Requirements of such an environment include quickness, treating scale, working at multiple levels of detail, dealing with design variability, and realistic representation of the work. Use is made of a realistic example to highlight aspects of our approach and identify important issues that must be addressed if a visualization environment useful for construction professionals is to be developed.

There is a great potential to improve the flow of resources through locations on construction sites, termed work-flow. Current activity-based scheduling techniques do not provide adequate support for the planning of work-flow due to practical and methodological reasons. Location-based scheduling techniques provide a promising alternative to activity-based scheduling techniques for planning of work-flow. However, neither location-based nor activity-based scheduling techniques provide users with insight in the spatial configuration of scheduled construction operations. A technique that can provide this insight is 4D CAD in which 3D CAD models are combined with data from construction schedules. This article presents a process method for the planning of work-flow by combined use of location-based scheduling and 4D CAD. We suggest that a location-based approach to 4D CAD can improve the usability of the 4D CAD models for work-flow analyses. In addition, the article suggests that 4D CAD can enhance the value of location-based schedules.

This paper presents time–space analyses of construction operations supported by quantitative information extracted from 4D CAD models. The application of 4D models is a promising approach to help introduce construction innovations and to evaluate construction alternatives. Current analyses of 4D models are mainly visual and provide project stakeholders with a clear, but limited, insight of construction planning information. This practice does not take advantage of the quantitative data contained in 4D models. We use two 4D models of an industry test case to illustrate how to analyze, compare, and present 4D content quantitatively (i.e., workspace areas, work locations, and distances between concurrent activities). This paper shows how different types of 4D content can be extracted from 4D models to support 4D-content-based analyses and novel presentation of construction planning information. We suggest further research aimed at formalizing the contents in 4D models to enable comparative quantitative analyses of construction planning alternatives. Formalized 4D content can enable the development of reasoning mechanisms that automate 4D-model-based analyses and provide the data content for presentations of construction planning information.

4D CAD models that integrate physical 3D elements with time, have been used to visualize construction processes in several projects worldwide. 4D models have been used and have been shown to have benefits over processes that span the entire lifecycle of a project such as collaboration with stakeholders, making design decisions, assessing project constructability, identifying spatial conflicts in construction and so on. Despite these benefits, several organizational and project-specific barriers have hindered the widespread adoption of 4D CAD. In order to reconcile the theoretical benefits of 4D models with the practical difficulties faced in implementation, there is an urgent need to explore the implementation of 4D models on construction sites as well as the perceptions of intended users/beneficiaries towards this implementation. This paper aims to address this need and contribute to our understanding of how 4D models must be introduced, positioned and implemented on construction sites, so as to maximize both their acceptability and their usefulness. We describe two 4D models of infrastructure projects and two 4D models of commercial projects that have been built and implemented. Through a process of structured and unstructured interviewing the paper gauges the response of project participants across various organizational levels on each of these projects as to the usefulness of 4D in project planning and control. Through qualitative and statistical analysis of the data we establish that 4D CAD is likely to be most beneficial in the project shaping or planning stage and in the construction stage. In the project shaping stage, 4D CAD is likely to be particularly useful in communicating construction plans and processes to clients, while during the construction phase, 4D CAD is likely to be particularly useful in comparing the constructability of work methods visually in order to detect conflicts or clashes, and as a visual tool for contractors, clients, subcontractors and vendors to review and plan project progress. Further, upper management and site workers are more likely to use and derive benefits from the visualization of processes using 4D given their lack of site related knowledge or skills, while construction professionals who are more construction-savvy are more likely to appreciate and benefit from the analytical and planning aids that 4D simulations provide during the construction phase. However, it is likely that despite these benefits 4D CAD models might not diffuse through the construction industry unless 4D modelling and analysis is integrated into existing project planning approaches. The paper concludes with a brief discussion on future 4D software development that seeks to bring about such integration and leverages the benefits of 4D CAD to bring about improved operational efficiencies on construction sites.

This work focuses on identifying and minimising workspace congestions between construction activities' execution space. It develops a methodology and tool to assist planners with the assignment of activities' execution space, as well as identification and visualisation of workspace congestion. A literature review of workspace planning techniques revealed that traditional workspace planning techniques might not be able to detect and resolve workspace congestions.This paper establishes a new concept for ‘visualising workspace competition’ between the progressing activities through a number of objectives. A Critical Space-time Analysis (CSA) approach was developed to model and quantify workspace congestions. Subsequently a multi-criteria function embedding spatial and schedule related criteria, was designed to measure the severity of workspace congestions. A dynamic 4D simulation environment was developed by utilising three workspace planning features, these are: the twelve execution patterns, the three different work rate distributions, and a time-based simulation of the progressing quantities of work. These were encapsulated in an innovative visual 4D CAD tool dubbed PECASO (Patterns Execution and Critical Analysis of Site-space Organisation), which was developed and evaluated in a case study project.The paper concludes that the CSA approach reduces the number of competing workspaces and conflicting volumes between occupied workspace. The PECASO tool assists the planners' decision making to produce a better execution strategy for a given project schedule. It also contributes to future research and knowledge of 4D workspace planning.

The Analytic Hierarchy Process (AHP) approach is widely used for multiple criteria decision-making in construction management. However, the traditional AHP requires that decision makers remain consistent in making pairwise comparisons among numerous decision criteria. Accurate expression of relative preferences on the criteria is difficult for decision makers due to the limitations of the 9-value scale of Saaty. Although Saaty proposed a method to assess the consistency of pairwise comparisons, no automatic mechanism exists for improving the consistency for AHP. This work proposes an adaptive AHP approach (A3) that uses a soft computing scheme, Genetic Algorithms, to recover the real number weightings of the various criteria in AHP and provides a function for automatically improving the consistency ratio of pairwise comparisons. A real world construction management example for determining the weightings of the multiple criteria for a best-value bid is chosen as a case study to demonstrate the applicability of the proposed A3. The application results show that the proposed A3 is superior to the traditional AHP in terms of cost effectiveness, timeliness, and improved decision quality.

This paper describes a teaching project, carried out in the postgraduate program of the ETH in Zurich, whose goal was to apply multimedia, Internet-based technology to a study of the work of the Finnish architect Alvar Aalto. The goal of the course was twofold: to learn about the architecture of Aalto while teaching students to design a web site, using dynamic pages and databases. The outcome of the course was a web site in which the work of Aalto is represented in three distinctive contexts: descriptive, analytical and associative. The rich network of connections within and between the different contexts allows the visitor of the site to gain new insights on the work of Aalto in a truly interactive way.

The digital design studio has an area of application where conventional media are incapable of being used; collaboration in learning, design and dialogue with people in places other than where one lives. This distinctive opportunity has lead the authors to explore a form of design brief and virtual design studio (VDS) format not well addressed in the literature. Instead of sharing the same design brief, students in this alternative format design a project in the other students' city and do not collaborate on the same design. Collaboration with other students takes the form of teaching each other about the city and culture served by the design. The authors discovered these studios produce a focus on site context that serves our pedagogical objectives - a blend of architectural, landscape architectural and urban design knowledge. Their students use a range of commercial CAD and computer supported collaborative work (CSCW) software common to that used in many VDS experiments reported on in the literature. However, this conventional use of technology is contrasted with a second distinctive characteristic of these studios, the use of custom software tools specifically designed to support synchronous and asynchronous three-dimensional model exchange and linked attribute knowledge. The paper analyzes some of the virtual design studio (VDS) work between the Swiss Federal Institute of Technology, the University of Toronto, and the University of Melboume. The authors articulate a framework of VDS dimensions that structures their teaching and research.

Considering the characteristics of highly specialized corporation in the construction industry, it's crucial to select appropriate subcontractors to implement specific subprojects. In this research, the overall subcontracting supply chain of a construction project is considered as a global procurement system and an optimal combination of subcontractors can be obtained within this system. Combining the quick response mechanism of information technology with portfolio theory in financial management, an integrated XML (eXtensible Markup Language) of Accelerated Subcontracting And Procuring (ASAP) model was proposed. The ultimate goal of this study is not only to develop a web-based decision support system for general contractors to accurately decide an appropriate trade-off between risk and profit for different combinations of subcontractors, but to take the subcontracting and procuring process into re-engineering through omnipresent Internet.

Complexities in building technology when not fully understood, have resulted in a less than favorable aggregate impact on the building's environment. A surprisingly high portion of U.S. non-industrial buildings do not provide satisfactory task environments. Developments in computer technology have infused new thought processes in the way we plan, design, build and operate our buildings. This paper proposes a social and technical use of Knowledge-based-systems (KBS) for continuous accountability to assure healthy buildings. Diagnostics, as an emerging discipline in building design and operation, is also discussed. A proposed framework for such accountability and the resulting ‘chain of custody’, that draws on the medical paradigm and associated diagnostic procedures is presented. It is suggested that KBS also be used for the development and interpretation of criteria for evaluating building performance from initial conception through design, construction and operation. Thus, KBS is expected to aid in the analysis of ‘virtual’ and ‘actual’ buildings that may be ‘sick’ or ‘healthy’. It is proposed that for a building to provide satisfactory performance over its life-time, the ‘life-cycle’ concept must be modified in terms of the roles, responsibilities, and configuration of the building team, and in terms of its costing procedures.

This study examines user acceptance of building management systems (BMS) using a questionnaire survey. These systems are crucial for optimising building performance and yet it has been widely reported that users are not making full use of their systems' facilities. Established models of technology acceptance have been employed in this research, and the positive influence of user perceptions of ease of use and compatibility has been demonstrated. Previous research has indicated differing levels of importance of perceived ease of use relative to other factors. Here, perceived ease of use is shown generally to be more important, though the balance between this and compatibility is moderated by the user perceptions of voluntariness.

Automated monitoring systems are important in civil engineering industry. Existing utilities and infrastructures are monitored when their safety is of concern. These monitoring data also provide key indicators for their health and information for the life cycle management. With the prevalence of wireless sensor network (WSN) technology and the availability of various wireless communication technologies, large-scale automated monitoring systems can be deployed easily, and the cost of such systems are dropping owing to the use of Micro-Electro-Mechanical System (MEMS) technology. In this work, potential technologies for next-generation automated monitoring systems are first visited. A scalable IT (Information Technology) infrastructure for supporting large-scale automated monitoring systems capable of handling multiple projects is then proposed. Scalability, reliability, and extensibility are main considerations when designing the system and when choosing the technology for the system. Some scenarios are presented to demonstrate the characteristics and capabilities of the proposed infrastructure and information systems.

The ability over the course of a construction project to make reliable predictions regarding cash flows enhances project cost management. This paper uses artificial intelligence (AI) approaches to predict cash flow trends for such projects in order to develop appropriate strategies that apply factors such as float, process execution time, construction rate and resource demand to project cash flow control. AI approaches involved in this paper include K-means clustering, genetic algorithm (GA), fuzzy logic (FL), and neural network (NN). K-means clustering is employed to categorize similar projects, while the other approaches are used to develop the Evolutionary Fuzzy Neural Inference Model (EFNIM), a knowledge learning model. FL and NN are employed in the EFNIM to develop a neural-fuzzy model that can deal with uncertainties and knowledge mapping. GA is used to optimize the membership functions of FL and NN parameters globally. The major target of this AI learning is to address sequential cash flow trends. This trained result is furthermore applied to a strategic project cash flow control. This cash flow control affects project performance within the banana envelope of the S-curve for project management.

This paper presents a working hypothesis for the development of Architectural Acoustics teaching software. The concepts and rationale underlying the development are discussed first and followed by a presentation of current first-phase 2D work in progress. The paper includes mention of some of the strengths and weaknesses of this first-phase work as well as our initial thoughts and intentions about desirable features for a full 3D implementation.

This paper describes research results into the identification of heavy construction equipment, i.e., off-road trucks and scrapers, using acoustical measurements. Characterization of the load status, i.e., loaded or empty, is also described. Field sound measurements were gathered using an ordinary videocassette recorder. The sound signal was processed using a Fourier Transformation algorithm. Features of the acoustical signature were measured, and differences between trucks and scrapers were noted. Probabilities were established to define the likelihood that a signal was produced by a particular type of equipment. Characteristics of the load status were also defined. The research demonstrates the feasibility of identifying equipment type and load status using a passive acoustic sensor.

This paper describes a methodology for constructability knowledge acquisition of construction technologies. The methodology combines a neuro-fuzzy network-based approach with genetic algorithms. The combination of fuzzy logic with learning abilities of neural networks and genetic algorithms may allow for automatic acquisition of constructability knowledge from training examples and for providing understandable explanations for the reasoning process. The proposed methodology can provide a mechanism to trace back factors causing unsatisfactory construction performance and the necessary feedback to construction engineers for technology innovation. An application example is provided to demonstrate the capabilities of the proposed methodology.

Site modeling can be useful in various safety-enhancement applications and for as-built data acquisition. In this article, a rapid, on-site, spatial-modeling method using a “sparse point cloud” approach that represents construction sites in an efficient manner is proposed. The various procedures used in the modeling process are explained. The results of the experiments performed on actual construction sites are described, as are case studies of the modeling method per se. An example of the application of the proposed site modeling method to the simulation of obstacle-avoidance in the operation of equipment on an industrial construction project is also presented.

It is the time resource that one deals with in scheduling. The task is how one can achieve the optimal allocation of a given time resource over a set of assigned activities. Most of the existing scheduling methods use a parametric time by which the activities are orderly allocated in accordance with the order of events. The parametric methods, however, fail in incorporating a dynamic aspect of scheduling that unfolds itself as the project proceeds, and also uncertainty that the starting and ending nodes of an activity fluctuate. This paper reformulates the concept of time to match to a dynamic scheduling through a non-deterministic approach. In particular, time can be regarded as an object in the holographic space, which models the dynamic aspects of time as a “mapped/represented” and “transformed/processed” temporal movement.

In recent years, many new technological solutions have been introduced, aiming to improve the ability of buildings to satisfy a variety of needs of human beings and the environment. As a consequence, designing an optimal building has become more challenging than it has been before.In this article, a multi-criteria “knapsack” model is proposed to help designers to select the most feasible renovation actions in the conceptual phase of a renovation project. Firstly, the methodology is described. Then, a case study is presented. Finally, advantages and disadvantages of the methodology are considered and needs for future research are suggested.

In line with the promotion of sustainable construction in the past decade, construction professionals have been contributing efforts in protecting the environment in implementing construction activities. Whilst such efforts will be contributed continuously, it is important that the level of the environmental performance in implementing construction activities can be properly measured and communicated to the public and project participants. This paper presents a scoring method for measuring the environmental performance committed by a contractor through calculating the contractor's environmental performance score (EPS). The level of EPS serves as a simple indicator for measuring and communicating the level of a contractor's environmental performance. The procedure for calculating EPS is formulated as an information technology (IT)-supported program. The program is designed not only to calculate EPS but also to allow for assisting contractors in diagnosing the causes of possible poor environmental performance. The diagnosis should enable the project parties involved to identify and adopt proper measures to improve environmental performance during implementing construction activities. A case study is formulated from a simulated environment for demonstrating the application of the EPS system.

Cooperative erection activities are critical to projects which involve the erection of heavy loads or the installation of special equipment. Detailed simulation on computer prior to construction can identify constructability problems, and subsequently avoided during actual erections. This paper describes an integrated approach for simulating the detailed motions of cranes. This research develops a physics-based model that follows the principle of closed-form forward kinematics and constraint-based dynamics to present the dual-crane mechanism mathematically — a non-trivial task. This model can be used to analyze the inputs from the users (i.e. virtual crane operators) and simultaneously compute the cables sway and reaction of collisions. We also implemented the model on computer and developed a simulation system, Erection Director, to render realistic cooperative erection activities. A demonstration of simulating two-crane lift has been built and three performance tests including a small building (840 elements), a medium building (1937 elements) and a large building (2682 elements) validate the feasibility of the proposed approach. The test results indicate that Erection Director can support real-time and physics-based visualization of cooperative erections.