Carl T. Haas

A proximity-based method for locating RFID tagged objects

This paper presents a method intended to extend the use of current radio frequency identification (RFID) technology to tracking the precise location of tagged materials on construction sites. The performance experienced with a commercially available RFID system is compared with the theoretical performance derived from an analytical discrete framework. Also through experimentation, the effects of parameters including RF power, the number of reads, and tag density are assessed, and their performance trade-offs are characterized to suggest guidelines for potential field deployment.

State of research in automatic as-built modelling

Building Information Models (BIMs) are becoming the official standard in the construction industry for encoding, reusing, and exchanging information about structural assets. Automatically generating such representations for existing assets stirs up the interest of various industrial, academic, and governmental parties, as it is expected to have a high economic impact. The purpose of this paper is to provide a general overview of the as-built modelling process, with focus on the geometric modelling side. Relevant works from the Computer Vision, Geometry Processing, and Civil Engineering communities are presented and compared in terms of their potential to lead to automatic as-built modelling.

Tracking the Built Status of MEP Works: Assessing the Value of a Scan-vs-BIM System

AbstractMechanical, electrical, and plumbing (MEP) works constitute a large portion of construction costs and thus need to be appropriately tracked. Assessment of the built status of MEP works in construction projects is however typically limited to subcontractor claims augmented and contrasted with periodic manual inspection. A more detailed manual inspection is costly and not considered worthwhile on most projects. Within a Scan-vs-BIM object recognition framework, three-dimensional laser scanning and project 3D/4D BIM models jointly offer the opportunity for a frequent, detailed, and semantically rich assessment of as-built status of construction projects at a cost that continues to decline. This potential has already been demonstrated for tracking structural works, but remains to be assessed in regard to other work sections, in particular MEP works. This paper explores that opportunity. A Scan-vs-BIM processing system is described with some enhancements over previous works. It is then tested with a re...

Application of system dynamics for developing financially self-sustaining management policies for water and wastewater systems

Recently enacted regulations in Canada and elsewhere require water utilities to be financially self-sustaining over the long-term. This implies full cost recovery for providing water and wastewater services to users. This study proposes a new approach to help water utilities plan to meet the requirements of the new regulations. A causal loop diagram is developed for a financially self-sustaining water utility which frames water and wastewater network management as a complex system with multiple interconnections and feedback loops. The novel System Dynamics approach is used to develop a demonstration model for water and wastewater network management. This is the first known application of System Dynamics to water and wastewater network management. The network simulated is that of a typical Canadian water utility that has under invested in maintenance. Model results show that with no proactive rehabilitation strategy the utility will need to substantially increase its user fees to achieve financial sustainability. This increase is further exacerbated when price elasticity of water demand is considered. When the utility pursues proactive rehabilitation, financial sustainability is achieved with lower user fees. Having demonstrated the significance of feedback loops for financial management of water and wastewater networks, the paper makes the case for a more complete utility model that considers the complexity of the system by incorporating all feedback loops.

The divergence in aggregate and activity estimates of US construction productivity

Discrepancies exist between aggregate and activity productivity measurements in the US construction industry. Multiple studies using aggregate industry measures suggest that construction productivity has declined over the long term. A longstanding problem with the aggregate measures concerns the difficulty of controlling for inflation so as to accurately measure real output. As an alternative, average activity productivity, measured by individual work activities, indicates that construction productivity has increased over the same time period. Activity measurement data have been collected for 200 construction activities over a 22-year time period from commercial estimation manuals used by contractors and owners to estimate the cost and time requirements for construction. This paper examines the discrepancies between aggregate and activity measurements and suggests possible reasons for their existence.

Robotics in Civil Engineering

Abstract: Robots have been investigated for automation of construction, maintenance, and inspection of civil works since the early 1980s. This paper describes the progress of robotics in civil engineering from the early 1980s to the mid-1990s. It focuses on the environment and motivation for implementation of robotics, identifies key centers of development, identifies regional differences, and describes progress in key areas. It also traces the emergence and change of development strategies over time, it identifies practical achievements, and it identifies key developments for the future. It concludes that despite many false starts and setbacks, significant progress has been made, and significant changes are on the horizon.

A framework for rapid local area modeling for construction automation

Rapid 3D positioning and modeling in construction can be used to more effectively plan, visualize, and communicate operations before execution. It can also help to optimize equipment operations, significantly improve safety, and enhance a remote operators spatial perception of the workspace. A new framework for rapid local area sensing and 3D modeling for better planning and control of construction equipment operation is described and demonstrated. By combining human-assisted graphical workspace modeling with pre-stored Computer-Aided Design (CAD) models and simple sensors (such as single-axis laser rangefinders and remote video cameras), modeling time can be significantly reduced while potentially increasing modeling accuracy.

Toward automated earned value tracking using 3D imaging tools

AbstractAccurate and frequent construction progress tracking provides critical input data for project systems such as cost, schedule control, and billing. Unfortunately, conventional progress tracking is labor intensive, sometimes subject to negotiation, and often driven by arcane rules. Attempts to improve progress tracking have recently focused on automation, using technologies such as three-dimensional imaging, global positioning systems, ultra wide band (UWB) indoor locating, handheld computers, voice recognition, wireless networks, and other technologies in various combinations. However, one limit of these approaches is their focus on counting objects or milestones rather than value. In this paper, a four-dimensional model recognition-driven automated progress tracking system that transforms objects to their earned values is examined via the analysis of data from the construction of a steel reinforced concrete structure and a steel structure. It is concluded that automated, object oriented recognitio...

The Value of Handheld Computers in Construction

Construction is an information intensive industry in which the accuracy and timeliness of information is paramount. Construction projects can experience extensive delays or rework due to information that is unavailable, inaccurate or simply outdated. Handheld computers (HHC) have the potential to solve some of these problems by providing field workers with accurate, reliable and timely information at the location where it is needed. Thus, HHC’s can increase the amount of direct work on a project indirectly by directly decreasing the time spent on support work (such as accessing drawings and sending RFI’s) and by reducing idle time. Applying a HHC evaluation method to 6 hypothetical construction field activities (punchlisting, materials tracking, MSDS access, drawing access, RFI’s, and quantity surveying) showed that HHC’s could potentially save time and improve accuracy at the task and activity levels of a construction project. However, barriers related to the HHC’s technological limitations and to the nature of the construction industry must be overcome in order to reap the full benefits of HHC’s.

Relationship between Automation and Integration of Construction Information Systems and Labor Productivity

Information technology (IT) has been used to increase automation and integration of information systems on construction projects for over two decades. However, evidence that overall costs have been reduced or project performance has been improved with IT in construction is limited and mostly focused on application specific studies. A comprehensive understanding of the relationship between IT and project performance helps industry practitioners better understand the likely outcomes of implementation of IT application and likewise benefits researchers in improving the effectiveness in their IT development efforts. An opportunity to examine new evidence exists with the emergence of the Construction Industry Institutes Benchmarking and Metrics database on construction productivity and practices. This article presents an analysis of that data to determine if there is a relationship between labor productivity and level of IT implementation and integration. Data from industrial construction projects are used to measure the relationships between the automation and integration of construction information systems with productivity. Using the independent sample t-test, the relationship was examined between jobsite productivity across four trades (concrete, structural steel, electrical, and piping) and the automation and integration of various work functions on the sampled projects. The results showed that construction labor productivity was positively related to the use of automation and integration on the sampled projects.