Rock Products

MAR 2013

Rock Products is the aggregates industry's leading source for market analysis and technology solutions, delivering critical content focusing on aggregates-processing equipment; operational efficiencies; management best practices; comprehensive market

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LOADOUT TRANSPORTATION Measuring Stockpiles with 3D Mobile Laser Scanning By Richard A. Hisert and Trevor R. Thomas CHALLENGE Performing physical inventories of material stockpiles. SOLUTION Mobile Laser Scanning. TIP The H2H mobile laser scanning system is easily mounted on the back of a standard SUV. A 3D model of found conditions. It is not that often that a new technology comes along that effectively makes the old methods obsolete. The personal computer, Global Positioning System (GPS) and the In��� ternet are a few examples of technology breakthroughs that once they became avail��� able, there was no going back. Mobile laser scanning, or what some refer to as LiDAR (think of radar, but instead of radio waves a laser beam is used) is one of those ���game��� changing��� technologies. Instead of collecting one 2D survey point at a time with laser scanning, you are collect��� ing tens of thousands of 3D points per sec��� ond. Now mount the laser scanner on a vehicle and drive around a stockpile or quarry and you will have the data needed to develop a highly accurate 3D model of the as found conditions. If you do this on a re��� curring basis you can then calculate the changes in the size, shape and volume of materials. As we know, performing physical invento��� ries of material stockpiles and quarries is a task that most companies see as a neces��� sary evil ��� it is something that has to be done for accounting purposes, but it takes up valuable resources and can slow down production. At the same time the accuracy and traceability of the methods are impor��� tant from the accounting side and need to be consistent from inventory to inventory so that the results can be relied upon. After all, these are valuable corporate assets that are being characterized. Accuracy Steve Brooks, plant manager for Tilcon in Poughkeepsie, N.Y., wanted to use the most accurate method available to inventory his company���s stockpiles. Tilcon is an inte��� grated materials company with multiple New York and New Jersey operations that include quarries, asphalt plants, recycling plants, water terminals and a heavy high��� way construction division. Brooks noted, ���About three years ago we began to investigate the use of 3D laser scanning.��� Instead of collecting 10 to 20 shots on a typical 20,000 CY stockpile using a total station, with laser scanning on the order of 100,000, 3D points are typically collected for that same pile. The spacing of the laser���scanned points on the pile surface is typically on the order of 3 to 6 in. Manual surveys cannot begin to match this level of surface detail. In fact, the laser scanning field crew has to be careful not to collect too much data because this can bog down the post processing and data analy��� sis without significantly improving the end result. ���We were using a different laser scanning contractor when we became aware of the mobile laser scanning based methodology that H2H offers. We made the decision to give it a try and have been very impressed with the results,��� Brooks commented. The H2H mobile laser scanning system is easily mounted on the back of a standard SUV. The 3D point data is collected by driv��� ing around the stockpile typically at a speed of 5���10 mph with the scanner rotat��� ing at 1,800 revolutions per minute. The mobile laser scanning system includes a GPS receiver and IMU (inertial measure��� ment unit) that allows the data to be geo��� referenced to the exact location on the earth. This insures that each inventory op��� 56 ROCKproducts ��� MARCH 2013

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