Real-Time Visualization for Prevention of Excavation Related Utility Strikes.

An excavator unintentionally hits a buried utility every 60 seconds in the United States, causing several fatalities and injuries, and billions of dollars in damage each year. Most of these accidents occur either because excavator operators do not know where utilities are buried, or because they cannot perceive where the utilities are relative to the digging excavator. In particular, an operator has no practical means of knowing the distance of an excavator’s digging implement (e.g. bucket) to the nearest buried obstructions until they are visually exposed, which means that the first estimate of proximity an operator receives is often after the digging implement has already struck the buried utility. The objective of this dissertation was to remedy this situation and explore new proximity monitoring methods for improving the spatial awareness and decision-making capabilities of excavator operators. The research pursued fundamental knowledge in equipment articulation monitoring, and geometric proximity interpretation, and their integration for improving spatial awareness and operator knowledge. A comprehensive computational framework was developed to monitor construction activities in real-time in a concurrent 3D virtual world. As an excavator works, a geometric representation of the real ongoing process is recreated in the virtual environment using 3D models of the excavator, buried utilities and jobsite terrain. Data from sensors installed on the excavator is used to update the position and orientation of the corresponding equipment in the virtual world. Finally, geometric proximity monitoring and collision detection computations are performed between the equipment end-effector and co-located buried utility models to provide distance and impending collision information to the operator, thereby realizing real time knowledge-based excavator operation and control. The outcome of this research has the potential to transform excavator operation from a primarily skill-based activity to a knowledge-based practice, leading to significant increases in construction productivity and safety. This is turn is expected to help realize tangible cost savings and reduction of potential hazards to citizens, improvement in competitiveness of U.S. industry, and reduction in life cycle costs of underground infrastructure.PHDCivil EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/96133/1/stalmaki_1.pd

Web-based Visualisation for Look-Ahead Ground Imaging in Tunnel Boring Machines

Tunnel Boring Machines (TBMs) are large multi-million pound machines used to excavate underground tunnels. In order to make best use of the high-speed performance of a TBM and guarantee the safety of excavation, it is important to know the local geology, structures and ground properties ahead of the TBM cutter head, especially in complex geological conditions (e.g. karst caves). By working with experienced geophysical experts, tunnelling engineers/consultants and TBM manufacturers, we propose a novel web-based visualisation platform to help TBM operators efficiently manage, process and visualise the TBM parameters, the geology map created by geo-experts based on boreholes, and especially the imaging data captured by an on-board ground imaging system for "seeing through" the ground beyond the excavation surface. Informative visualisation interfaces were designed to facilitate interpretation of the imaging data and adding annotation by users; algorithms were developed for automatic detection of features and probable events by fusion of radar and seismic imaging data; and a back-end database was designed to store all such relevant information for supporting more advanced interpretation in the future. The web-based architecture not only allows the visualisation platform to be directly linked to on-board sensors (e.g. ground penetrating radars, seismic sensors), but also allows users away from the job site to access the captured data using a standard web browser, enabling a collaborative interpretation process. The data processing, management and visualisation platform presented in this paper is flexible with respect to different imaging sensors and modalities, so it is highly adaptable for any other ground imaging systems for tunnel geology inspection, underground utility surveys, etc

Geospatial Databases and Augmented Reality Visualization for Improving Safety in Urban Excavation Operations

The U.S. has more than 14 million miles of buried pipelines and utilities, many of which are in congested urban environments where several lines share the underground space. Errors in locating excavations for new installation or for repair/rehabilitation of existing utilities can result in significant costs, delays, loss of life, and damage to property (Sterling 2000). There is thus a clear need for new solutions to accurately locate buried infrastructure and improve excavation safety. This paper presents ongoing research being collaboratively conducted by the University of Michigan and DTE Energy (Michigan's largest electric and gas utility company) that is investigating the use of Real-Time Kinematic global positioning system (GPS), combined with Geospatial Databases of subsurface utilities to design a new visual excavator-utility collision avoidance technology. 3D models of buried utilities are created from available geospatial data, and then superimposed over an excavator's work space using geo-referenced Augmented Reality (AR) to provide the operator and the spotter(s) with visual information on the location and type of utilities that exist in the excavator's vicinity. This paper describes the overall methodology and the first results of the research

Enabling Housing Cooperatives: Policy Lessons from Sweden, India and the United States

Housing cooperatives became active in urban areas in Sweden, India and the United States during the interwar period. Yet, after the second world war, while housing cooperatives grew phenomenally nationwide in Sweden and India, they did not do so in the United States. This article makes a comparative institutional analysis of the evolution of housing cooperatives in these three countries. The analysis reveals that housing cooperatives' relationship with the state and the consequent support structures explain the divergent evolution. Although the relationships between cooperatives and the state evolved over time, they can be characterized as embedded autonomy, overembeddedness and disembeddedness in Sweden, India and the United States respectively. Whereas the consequent support structures for housing cooperatives became well developed in Sweden and India, such structures have been weak in the United States. The article highlights the need for embedded autonomy and the need for supportive structures to enable the growth of housing cooperatives. Copyright (c) 2010 The Author. Journal Compilation (c) 2010 Joint Editors and Blackwell Publishing Ltd.