Sensor Network for Structural Health Monitoring of a Highway Bridge

A bridge monitoring TestBed is developed as a research environment for sensor networks and related decision-support technologies. A continuous monitoring system, capable of handling a large number of sensor data channels and three video signals, is deployed on a four-span, 90-m long, reinforced concrete highway bridge. Of interest is the integration of the image and sensor data acquisition into a single computer, thereby providing accurate time synchronization between the response and corresponding traffic loads. Currently, video and acceleration records corresponding to traffic induced vibration are being recorded. All systems operate online via a high-speed wireless Internet network, allowing real-time data transmission. Elements of the above health monitoring framework are presented herein. Integration of these elements into an automated functional system is emphasized. The recorded data are currently being employed for structural system identification via a model-free technique. Effort is also underway to correlate the moving traffic loads with the recorded accelerations. Finally, the TestBed is available as a resource for verification of new sensor technologies, data acquisition/transmission algorithms, data mining strategies, and for decision-support applications.     

Expert Systems for Construction Project Monitoring

Potential applications of knowledge based expert systems in the area of construction project monitoring and control are described. Originally developed from research in artificial intelligence, these systems are computer programs that can undertake intelligent tasks currently performed by highly skilled people. While some project monitoring can be accomplished by algorithmic procedures, the capability of knowledge based expert systems to deal with illstructured problems and to be extensively modified over time make them desirable for application in this area. Sample applications and heuristic rules in scheduling and inventory control are provided.     

Characterization and Search of Construction Inspection Plan Spaces Developed Using a Component-Based Planning Approach

Formal construction inspection planning is needed to help reduce the incidence of overlooked or inefficient inspections, and to help realize the potential of emerging sensing technologies. Prior publications by the authors have presented requirements for such an approach and a component-based inspection planning implementation as an approach in addressing some of the requirements towards formal construction inspection planning. Implementation of such a component-based approach for typical construction examples, however, leads to the generation of large, rugged search spaces. This paper first describes the characteristics of search spaces that are generated using a component-based approach to illustrate which search mechanisms are appropriate to explore these search spaces. The paper then describes a set of search algorithms and heuristics that were investigated and evaluated for searching construction inspection plans. Specific discussions on how these algorithms performed in searching within inspection planning spaces are provided based on experiments conducted using a testbed characterizing a construction site and a building performance monitoring decision-making example.     

Characterization of Wireless Smart Sensor Performance

A critical aspect of using wireless sensors for structural health monitoring is communication performance. Unlike wired systems, data transfer is less reliable between wireless sensor nodes owing to data loss. While reliable communication protocols are typically used to reduce data loss, this increase in communication can drain already limited power resources. This paper provides an experimental investigation of the wireless communication characteristics of the Imote2 smart sensor platform; the presentation is tailored toward the end user, e.g., application engineers and researchers. Following a qualitative discussion of wireless communication and packet delivery, a quantitative characterization of wireless communication capabilities of the Imote2 platform, including an assessment of onboard and external antenna performance, is provided. Herein, the external antenna was found to significantly outperform the onboard antenna in both transmission and reception reliability. However, the built environment, including building materials and other wireless networks, can significantly reduce reception rate and thus increase packet loss. Finally, implications of these results for a full-scale implementation are presented.     

Embedded System for Construction Asset Tracking Combining Radio and Ultrasound Signals

Today’s sensor technology provides the increased opportunities for automation and improvement in data acquisition and construction processes. However, many current field practices at construction sites still rely on manual processes for asset tracking and information handling. Previous technologies, such as radio frequency identification and global positioning systems, do not provide a solution to automated asset tracking because of their limitations in terms of applicability and performance in a typical construction environment. This paper introduces a new development of an embedded sensor system for construction asset tracking by combining radio and ultrasound signals. We present the detailed hardware and software architecture and have implemented outdoor experiments to examine the accuracy and performance of the designed system. The results obtained showed the accurate distance and position estimation with enhanced networking flexibility. The findings and lessons learned from this research demonstrate the potential for future practical deployment of similar systems in many civil engineering applications.     

Visualization of Construction Progress Monitoring with 4D Simulation Model Overlaid on Time-Lapsed Photographs

The ability to effectively communicate progress information and represent as-built and as-planned progress discrepancies are identified as key components for successful project management that allow corrective decisions to be made in a timely manner. However, current formats of reporting (e.g., textual progress reports, progress curves, and photographs) may not properly and quickly communicate project progress. Current monitoring methods also require manual data collection and extensive data extraction from different construction documents, which distract managers from the important task of decision making. Therefore, to facilitate progress monitoring, this paper proposes visualization of performance metrics that aims to represent progress deviations through superimposition of four-dimensional (4D) as-planned model over time-lapsed photographs in single and comprehensive visual imagery. As a part of the developed system, registration of the 4D model with photographs, augmenting photographs, and occlusion removal for progress images are presented. While contextual information is preserved, the as-built photographs are enhanced and augmented with 4D as-planned model in which the performance metrics are visualized. The augmented photographs provide a consistent platform for representing as-planned, as-built, and progress discrepancies information and facilitate communication and reporting processes.     

Ubiquitous Agent-Based Communication in Construction

A large amount of information is generated, shared, and exchanged during a construction project. However, several studies have shown that effective communication in construction is seriously hampered due to a lack of appropriate data channels, inaccurate data transfers, long delays, etc. Web-based and wireless communication technologies, however, offer a rich set of new tools to bridge those chasms but may also overwhelm the many potential users with too much information. To address the apparent danger of information overload, agent mediated communication concepts have been designed to autonomously manage large amounts of information exchanges. This paper presents the result of an effort to test the functionality of ubiquitous communication applications over a wireless fidelity infranet installed on an “unfriendly” construction site. Various applications were successfully designed, built, and tested, demonstrating that a well designed 801.11b backbone network is able to link today’s “islands of information” on a working site. The value of this paper to researchers and practitioners is the lessons learned and the outcome of a variety of field tests with the prototype system.     

Developing a Resource Supply Chain Planning System for Construction Projects

The high variability of construction environments results in high construction-cost variation, especially in material costs. Inadequate planning may cause material shortages that delay the project schedule or, alternatively, a substantial increase in inventory costs by producing or supplying materials earlier than they are needed at the construction site. In order to solve these problems, this paper studies steel rebar production and supply operations and establishes an optimal model that minimizes the integrated inventory cost of the supply chain. Based on the optimal model, this paper develops a decision-support system to generate a production and supply plan for a supplier and buyers of steel rebar. After utilizing the decision-support system to create the supply and production plan, this paper analyzes the results to study the influence of transaction constraints on inventory cost. This paper also discusses cases of global optimization of the inventory cost for the entire supply chain and compares them with cases of local optimization for individual members.     

3D Scan Information Management System for Construction Management

This paper presents an internet-based three-dimensional (3D) scan information management system (3DSIMS) that can be used as an interface to input, display, and inspect design as-built construction information. This system is mainly developed using 3D scan data. The function of the 3DSIMS is to integrate the scan data collected before, during, and after a scan scheme that is designed to capture as-built 3D records. The information included in this system consists of a scan scheme, scanned point clouds, construction records, and postscan processed clouds for the display, search, and comparison of scans made each week during the construction of a campus building. This study represents a long-term effort that has rarely been done before. A web page is used to deliver and share scan information. The feasibility of this approach is explained by the examples of dimension-related checks through as-built data.     

Continuous Plume Monitoring Using Wireless Sensors: Proof of Concept in Intermediate Scale Tank

The current practice for monitoring of subsurface plumes involves the collection of water samples from sparsely distributed monitoring wells and laboratory analysis to determine chemical concentrations. In most field situations, cost and time constraints limit the number of samples that could be collected and analyzed for continuous monitoring of large, transient plumes. With the development of wireless sensor networks (WSNs), that allow sensors to be incorporated into a distributed wireless communication and processing system, the potential exists to develop new, efficient, economical, large-scale subsurface data collection and monitoring methods. This paper presents a proof-of-concept study conducted in a two-dimensional synthetic aquifer constructed in an intermediate scale test tank to demonstrate the feasibility of using WSN for subsurface plume monitoring. The tank was packed to represent a heterogeneous aquifer, and a sodium bromide tracer was used to create a plume. A set of ten wireless sensor nodes (motes) equipped with conductivity probes to measure electrical conductivity formed the network. Software for automated data acquisition was developed and tested. Results of two experiments conducted using this test system are presented. The lessons learned from the first experiment were used to make modifications to the way the sensors were placed, how they were calibrated and how the sensors were interfaced with the data acquisition system. The findings are used to identify future research directions and issues that need to be addressed before field implementations of a WSN based data collection system for plume monitoring.     

Knowledge Mining of Information Sources for Research in Construction Management

Extracting the right information at the right time is vital in any research project. Moreover, researchers generally seek innovative “knowledge mining” techniques for optimizing their research efforts within constrained time frames and with scarce resources. Meanwhile, rapid developments in the fields of computing and information technology drive the accelerated globalization process in both industry and academia. This paper explores some of the emerging technologies and associated research methodologies from an information supply chain perspective. An application in a recent Internet based two-phase questionnaire survey for design/build contractor selection provides a useful case study in the structuring of an innovative knowledge mining strategy. This experience feeds into the formulation of a “high-velocity” knowledge mining framework and a set of guidelines—to facilitate and enhance such innovative construction management research, while dealing with some initial issues/problems in the Internet based research environment. Furthermore, some critical success factors, key performance indicators, and mining strategies are consolidated for marshalling both vivid and tacit knowledge sources, such as by “exploiting” Internet resources for more creative and efficient construction management research.     

Fundamental Principles of Site Material Management

This paper was written to fill a void created by the absence of fundamental principles of site construction management. Efficient material management is essential to managing a productive and cost efficient site. For more than 25?years, the senior author has been observing and writing about inefficient labor productivity practices resulting from poor site material management. Using deductive reasoning, fundamental principles were developed to avoid poor practices. A construction site should be portioned into three areas or zones: semipermanent (exterior) storage, staging areas, and workface (interior) storage. Each has a unique function relative to site material management. Using these areas as a framework, fundamental principles are stated and illustrated using a case study project accompanied by numerous photographs and narratives.     

Aircraft Sensor and Actuator Fault Detection, Isolation, and Accommodation

The purpose of the paper is to present an approach to detect, isolate, and accommodate the aircraft sensor and actuator faults using unknown input observers (UIOs). Full-order observers, reduced-order observers, and UIOs are widely used in state estimations. After the estimation of states, fault detection can be provided by conducting residual analysis. Despite of the existence of unknown inputs, fault detection and isolation are implemented for a very large, four-engined, cargo jet aircraft model. Sensor accommodation is realized via switching under redundant sensor existence assumption. Actuator accommodation is provided by gain scheduling. Hence, if a fault occurs in an actuator corresponding to the control surfaces, the remainder (n?1) actuators are used to avoid hazardous flight. Sensor and actuator faults are detected by using residuals. Sensor faults are effective on the outputs, while actuator faults are effective on the state equations. Fault isolation is implemented by taking into account that each residual is sensitive to all of the other faults but one fault. Fault detection, isolation, and a recommended accommodation are shown through the simulations to be functional.     

Activity Awareness as an Enabler for Communication and Network Building in Construction Design Teams

The paper reports on ongoing research into the facilitation of communication in distributed design teams of the type typically encountered in the construction sector. Ideas around social aspects in such design teams are discussed followed by our previous research efforts as an evolutionary process that has led us to develop in this direction. It is argued that facilitating timely and contextually grounded communication in a distributed environment can help to build the social networks and associated social capital common in collocated design teams but often absent in distributed ones. We describe our framework for providing such facilitation through monitoring and awareness of the information “space” of a construction project. We believe that by leveraging the relationships in the information space, we can go some way to identifying those individuals who would benefit from developing interpersonal relations in their work and further by exploiting those relationships in real time we can accelerate the formation of personal social networks and social capital between those individuals.     

Project Planning for Construction under Uncertainty with Limited Resources

Much of the project scheduling literature treats task durations as deterministic. In reality, however, task durations are subject to considerable uncertainty, and that uncertainty can be influenced by the resources assigned. The purpose of this paper is to provide the means for contractors to optimally allocate their skilled workers among individual tasks for a single project. Instead of the traditional use of schedules, we develop control policies in the form of planned resource allocation to tasks that capture the uncertainty associated with task durations and the impact of resource allocation on those durations. We develop a solution procedure for the model and illustrate the ideas in an example. The data for the example is collected from a real project.     

Managing Construction Projects Using the Advanced Programmatic Risk Analysis and Management Model

Risk management is an important part of construction management, yet the risk-based decision support tools available to construction managers fail to adequately address risks relating to cost, schedule, and quality together in a coherent framework. This paper demonstrates the usefulness of the Advanced Programmatic Risk Analysis and Management Model (APRAM) originally developed for the aerospace industry, for managing schedule, cost, and quality risks in the construction industry. The usefulness of APRAM for construction projects is demonstrated by implementing APRAM for an example based on an actual building construction project and comparing the results with other risk analysis techniques. The results show that APRAM simultaneously addresses cost, schedule, and quality risk together in a coherent, probabilistic framework that provides the information needed to support decision making in allocating scarce project resources.     

Engineering Information Service Infrastructure for Ubiquitous Computing

This paper describes a software framework for the development of a ubiquitous computing environment for distributed engineering information services. Two fundamental issues are addressed: universal accessibility of devices to information services, and collaboration among the parties accessing the information services. The first calls for the development of device-independent information services that have the flexibility to support a wide range of client devices. We introduce a mediation-based framework that enables information clients to calibrate the source information services to the clients’ characteristics. The second requires effective integration of information services, which we address in two ways: (1) we sketch an ontology standard and describe how such a standard can be effectively applied for exchanging project scheduling and resource information; and (2) we illustrate an infrastructure that is particularly suitable for the integration of engineering services. A prototype for the ubiquitous computing environment has been developed that incorporates a variety of project management software as well as different devices ranging from PDAs to Web browsers, desktop computers, and servers.     

Resource Sharing in Linear Construction

In the method developed, the conventional method of allocating resources are not used. Instead, resource‐hour units are employed. This enables to allocate resources precisely and the analysis becomes realistic unlike any other method. The method uses linear programming to determine the maximum rate of construction and the resource requirements in various activities. Sharing of resources which are available in limited quantities and balanced trades are all catered for in this development. The economics of using additional resources, working overtime and the optimal usage of all resources are the more important aspects of this paper. The step by step process of introducing additional resources and overtime ease the decision making process considerably. The method also helps to determine whether it is more economical to invest in additional resources or introduce work on overtime. If there is no proper method to compute resource requirements, a considerable waste in resource utilization would result. If resources are under utilized, even by a very small quantity, a considerably large delay of time would incur.     

Ontology-Based Approach to Context Representation and Reasoning for Managing Context-Sensitive Construction Information

The construction industry is an information-intensive industry and heavily relies on documents, including physical and virtual documentation and models, to exchange context-sensitive information among different project participants. Many research efforts have been made to help manage construction information; however, few of them considered the context-sensitive nature of the information. In this paper, the writers propose a new approach to facilitate the management of context-sensitive construction information that is stored in different textual documents. The approach addresses the context-sensitive nature of construction information by representing contexts in ontologies and by using contexts as indices of the information. The approach also presents a reasoning mechanism that leverages the semantically rich features of ontologies to reason about contexts to evaluate their applicabilities. Two case studies were conducted, and the results showed the proposed approach can effectively retrieve, classify, and manage construction information. Finally, the writers discuss the limitations of the proposed approach and future research directions.     

MACROS: Multiobjective Automated Construction Resource Optimization System

This paper presents the development of a practical and automated system for optimizing the utilization of construction resources to simultaneously minimize project cost and duration while maximizing project quality. The system is named the Multiobjective Automated Construction Resource Optimization System (MACROS), and it incorporates four newly developed modules: (1) a multiobjective optimization module to quantify and optimize the impact of resource utilization decisions on construction duration, cost, and quality; (2) a relational database module to facilitate the storage and retrieval of construction scheduling and optimization data; (3) a middleware module to provide seamless integration between the internal modules in MACROS and external commercially available project management software; and (4) a user interface module to facilitate the input of project data and the visualization and ranking of the generated optimal construction plans. An example project of 180 activities is analyzed to illustrate the use of MACROS and demonstrate its unique and practical construction optimization capabilities.