Cloos offers a specific example of the success of these mapping activi- ties: “Our wharves are supported over the water on piles, and there are access hatches to get to the substructure. That information used to live in site plans in white space; people had an idea what they might be looking for and where, but it was like trying to look for them from scratch each time or finding someone who might remember where the hatches were. Es² went out and put an accurate position on them all. Now, we can open the app and find them without having to pull out the old plans.” Rapidly mapping all of the expansion joints of the Huey P. Long bridge was done by mounting Trimble R2 rover on a high-track truck. Real-time corrections from the local VRS network yielded accurate locations, and the rover performed well despite the obscured sky view through the iron over structure.
This first GNSS field mapping phase for Port NOLA demonstrated that field mapping is a cost-effective alternative to legacy—often in- complete and inaccurate—records conversions. No matter how much legacy data is available, sometimes the only way to be sure of an asset is to field-locate, verify, and update. The Port of New Orleans is one of the busiest ports in North America, at the nexus of large continental navigable river and rail networks. An updated and modernized GIS was developed through the digitalization of legacy records, aerial imagery and GNSS field asset mapping.
the Asset Management sector. Traditional techniques of acquiring data such as ‘LiDAR’ are still in their infancy for use underwater. It has been proven that static Mechanical Scanning Sonar (MSS) scans have accuracy approaching that of Terrestrial Laser Scanner (TLS). Traditionally, high accuracy LiDAR surveys are acquired by mounting the Laser scanner on a tripod in fixed locations. The scanning locations are positioned using land survey techniques, and the scans are regis- tered to real world co-ordinates using LiDAR processing techniques. The application of this methodology underwater is widely accepted, where the sonar is mounted on a tripod or suspended from a crane. The model is then built from a series of scans from successive locations. Subsea bathymetric surveys offshore employ acoustic sensors, Multibeam Echo Sounders (MBES), to obtain depth/range measure- ments, which in turn form terrain models. In the context of a typical bathymetric survey, these sensors are deployed on a survey vessel and
Bibby HydroMap’s asset inspection surveys help assess storm damage
Excessive rainfall caused by Storms Ciara and Dennis earlier this year led to the wettest February since records began, leaving significant damage throughout many areas of the U.K. We recently worked with a national rail organization visiting flood affected areas of the country, inspecting bridges using high-resolution 3D sonars to locate areas of scour and prevent closures, to help keep Britain moving. Efforts to extend the capability of underwater inspection, focusing on submerged infrastructure are gaining wider attention and uptake within
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csengineermag.com
may 2020
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