US: No detail left behind

US: No detail left behind

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On a massive industrial park project, the laser scanning technology helps get it right the first time

For engineering firms, one of the biggest drawbacks to traditional surveying techniques has long been the need to revisit a project because some feature, some measurement, some element of the initial survey had either been missed or now needs to be expanded upon. Revisiting the site to resolve these issues can be costly, not only in budget dollars but, more importantly, in lost project time. So when Barghausen Consulting Engineers undertook a project to do ALTA (American Land and Title Association) surveys on a huge industrial site near Seattle, they opted to supplant the standard surveying approach with the use of a laser scanner.

The project was a 90-acre industrial site at which Barghausen was contracted to conduct a full ALTA survey as part of a new constructionrelated boundary-line adjustment. The site contains about 50 structures of different use, including manufacturing, office and storage, and it includes everything from a 100” plus tall buildings to underground tunnels. The demand of the project was to find an efficient and economical way to conduct the surveys while, at the same time, gathering sufficient data to eliminate having to repeatedly re-visit the site as new demands arose.

Over the course of six weeks, the Barghausen team set up in 88 scan positions and shot a total of 110 scans. While a traditional survey would probably have netted about 20,000 points, the Topcon GLS-1500 laser scanner has given them close a billion. “The laser scanner gathers data at a rate of about 30,000 points per second,” informs Trevor Lanktree, one of the company”s project surveyors. The overriding benefit derived from an instrument like the laser scanner in this application, is its ability to gather information which can be called up, examined, manipulated and measured at any time in the project. Lanktree says that it”s inevitable that the design team will soon start asking for additional data regarding onsite features and when they do, that”s when the savings on this project will just erupt. Had they done that project with a traditional instrument, they would have needed to go back out twice to reshoot it. That means incurring the cost of a crew, travel time there and back, setup time, and so on. Being able to expand the scope of the project by just manipulating data is an invaluable advantage. And it is an advantage that is quantifiable, he adds.

Based on work done at the industrial park to date, Lanktree estimates that the survey portion of the project has already come in 25% under budget.