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Topographic Survey
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Utility Survey
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Stationary LiDAR
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Subsurface Utility Exploration (SUE)
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Control Reports
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Completed July 2020
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Overview
To assist with a survey task of a larger project effort, GdB was contracted by Arora and Associates, P.C. for various survey tasks. At six specified crossings, GdB completed a survey of approximately 3,000 linear feet of roadway along the Trans-Manhattan Expressway Overpass. The topographic and utility survey of the local roads was performed using a combination of stationary LiDAR (High Density Laser Scanning) and traditional robotic total station survey methods. The stationary LiDAR allowed GdB to capture enough detail needed to create surface mapping contours at 0.2 foot intervals. Total Station surveying was used to complete the utility survey as well. GdB established a control network of points to complete this survey work. The datums were established by way of GPS observations on a pair of control points at either end. These points were post-processed using Leica Geo Office and referenced the NYSDOT CORS sites. A total station traverse was completed to set control at each intersection. Differential leveling between these points with a digital level and composite bar coded staff was performed to establish vertical values on these points. GdB established the vertical datum for the project by tying into First Order NGS benchmark disks recovered in the project area. Borough benchmarks were converted to NAVD88 datum. A total station traverse was performed to set control on the Trans-Manhattan Expressway. The survey of the Trans-Manhattan Expressway utilized mobile LiDAR methods. GdB established control and set target points on the Expressway for this purpose. The utility markout portion of the work was be performed by a third party sub-consultant to GdB Geospatial. The mobile LiDAR survey work was completed a third party sub-consultant to GdB Geospatial. Any Subsurface storm water and sanitary structures visible on site were investigated to determine pipe size, material and invert depth for the work above the TME only (along the six crossings).
GdB Value
All work was completed on time and within budget. A comprehensive control report was submitted to the Port Authority upon project completion