Shabtai Isaac

Can project monitoring and control be fully automated

An extended research programme has examined over the past two decades how productivity in construction projects can be improved through the development of models for project monitoring and control, which process automatically collected data on the actual project performance. Tests that were conducted with these models demonstrate that this approach can help overcome some of the limitations of existing manual methods. However, they also indicate that certain manually obtained data are still required in addition to the automatically collected data. A framework for semi-automated project monitoring and control is proposed, in which both manually and automatically collected data can be incorporated. This framework integrates the monitoring of projects with their control by taking into account the impact on productivity of existing deviations from the planned performance, and of the controlling actions that are proposed to deal with these deviations.

Risk-based models for emergency shelter and exit design in buildings

Mathematical models are presented that support the design of shelters and exits in buildings, along with hallway fortification strategies and associated evacuation paths. The objective of these models is to optimally protect building users and prevent casualties during emergencies by minimizing the risk to which evacuees are exposed during evacuation and after reaching their destinations. The models involve stochastic programming and robust optimization concepts under both user equilibrium (selfish) and system optimal (altruistic) conditions. These approaches are compared in a case study involving a single-story building. A multi-hazard approach is utilized in which the performance of a design is tested given various possible future emergency scenarios.

Construction site safety control with medium-accuracy location data

AbstractA statistical safety control method is presented that utilizes location data from a relatively inaccurate yet costeffective system to track workers in real time, and prevent unsafe situations at construction sites. In light of the inaccuracy of the tracking system, buffer areas are defined as statistical zones, at some distance from potential workplace hazards. Statistical alerts are created according to predefined rules when the hazard exposure of workers in those zones crosses a certain threshold. The results of tests of the method demonstrate that the model is able to successfully process the location data in order to compensate for its inaccuracy. This is done without necessitating a significant increase in the areas that are defined as being of high risk, and therefore off-limits for most workers on site. The model can thus ensure the efficiency of the construction work by restricting the size of the areas on site that are off-limits for most workers, while at the same time ensuring the safet...

An Ontology for Process Information Modeling

So far, the use of Building Information Modeling (BIM) to support automatic prefabrication and onsite assembly processes during a construction project has been limited. The modeling and management of information concerning the diverse elements involved in these construction processes, such as activities, objects, flows and operations, has not been sufficiently studied. In order to support the proper handling of construction process information and improve productivity, a process information modeling framework is developed in the present research. This paper presents an ontology model for supporting information handling of off-site automatic prefabrication and on-site assembly, which can incorporate manifold aspects (e.g. geometry, functionality, physicality) of building production subsystems. The object-oriented framework can support the semi-automatic preparation of digital information for off-site component prefabrication, and the simulation of the production process while considering variables such as the geometry of building components, material attributes and production speed. The framework can also support the definition of a project specific assembly activity and the simulation of on-site assembly activities such as component unloading, mounting, hoisting and positioning, while considering construction engineering constraints such as the lifting capacity and speed of cranes. As a result, the 3D model of the building component is updated to reflect its actual motion on the site during assembly processes.

Analyzing Building Information Using Graph Theory

The networks of interdependencies between elements in building projects, referred to as the project topology, are often complex and difficult for project teams to comprehend. It is hypothesized that a graphbased model of the project topology can be based on existing data in Building Information Models (BIM), facilitating the application of graph-theoretic algorithms to analyze this topology. The objective of this study is to propose an outline for the synthesis of BIM and graph theory. This synthesis is expected to contribute to the development of new tools for representing, managing and analyzing the design of building projects.

Work-Path Modeling and Spatial Scheduling with Singularity Functions

AbstractCurrent construction scheduling lacks an integrated planning approach that considers not just the time aspect of resources but also the physical workspace in which they interact. Therefore,...

Resource-Constrained Information Management: Providing Governments with Information for Earthquake Preparedness

This study seeks to attain a better understanding of the information that is required by governments to prepare for earthquakes, and of the constraints they face in obtaining this information. The contributions of the study are two-fold. A survey that was conducted among those responsible for earthquake preparedness actions in different governmental agencies and at different levels revealed on the one hand a desire for information on a broad range of topics, but on the other hand that no resources were allocated in practice to gather this information. A Geographic Information System-based process that was developed following the survey, allowed the required information on seismic hazards and loss and damage risks to be rapidly collected, mapped and integrated. This supported the identification of high-priority areas, for which a more detailed analysis could be initiated. An implementation of the process showed promise, and confirmed its feasibility. Its relative simplicity may ensure that an earthquake preparedness process is initiated by governments that are otherwise reluctant to allocate resources for this purpose.

Integrated Activity Scheduling and Site Layout Planning

A temporal-spatial scheduling model is used to consider the location and movement of equipment, material and temporary structures on a construction site over time, ensuring efficient yet safe processes. The model ties together activity scheduling and dynamic site layout planning, fully integrating two domains that have so far been treated separately. Their integration is facilitated by modeling temporary site objects like cranes as singularity functions. These objects are explicitly linked in the model with work spaces through Boolean operators.

A statistical safety control model for construction sites using location systems

A statistical safety control model is presented that utilizes data from a Real Time Location System of relatively low accuracy, to alert of unsafe situations at construction sites. Based on the Statistical Process Control methodology, predefined statistical rules are used to detect trends of increasing exposure to hazards, and provide proactive alerts before a critical exposure takes place. An initial verification of the performance of the model was carried out through extensive laboratory tests.