Processing Combined Laser, Sonar and HD Imaging for Better Evaluation Decisions
Abstract:From California to Massachusetts, from Ohio to Oklahoma, from 30-inch to 120-inch, round, odd-shaped, concrete and brick sewers, with and without flow and with inspection runs as long as 7,500-feet, new inspection technology providing data for condition assessments was considered impossible only a few short years ago. Although millions of feet of sewer lines are televised in the United States each year, larger interceptors that carry significant flow are often ignored because of accessibility issues, lack of redundancy, safety concerns, illumination, cost, clarity of information and the difficulty and cost of dewatering.
Since mid-2008, multi-sensor technology has provided the tools to finally overcome many of the obstacles that were encountered in the past. More and more municipalities are using this type of technology to inspect sewers and make more appropriate rehabilitation decisions, which continually proves the cost effectiveness of this value-added tool. Currently more than one million feet of large diameter sewers have been inspected using multi-sensor technology.
Using a combination of a high definition camera and various combinations of laser technologies above the water surface, observations of corrosion, deflection, ovality, missing brick courses, damaged pipes, poor bedding, etc. are recorded. Below the water surface, sonar technology identifies the depth and volume of debris and major structural anomalies without the need for expensive dewatering systems. When all of these data collectors are contained on a single delivery system, the inspections can be economically performed in a single insspection run.
The collected data is processed into a single submittal with videos simultaneously presenting the laser above the water surface and the sonar below the water surface. The HD camera data is submitted in a video with PACP coding that can be incorporated into most municipal databases. Data reports with still photographs, computer-generated drawings and findings at their specific locations supplement the videos.
Document Type: Research Article
Publication date: January 1, 2011
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