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Model-Based Deep Line Utility Survey
At a minimum, the reported horizontal and vertical accuracy of a Dual-Spar measurement can help determine where test holes are required. There will always be times where nothing but exposing a utility will satisfy the project requirements so test hole utility elevation determination will remain a key component of SUE. But in situations similar to those presented here, Dual Spar underground utility positioning technology represents a more economical alternative when managing SUE costs and risk.
Conventional locating methods depend on searching for peaks or nulls in the electromagnetic field, manually marking those locations and surveying the markings separately. This is an inefficient process and may lead to ambiguous or erroneous results, particularly for deep utility lines when detecting the precise location of the peak signal is difficult. Using ORI’s model-based technology, the utility can be accurately positioned without being directly above it or at any other special location. Vegetation, water or other obstructions over the utility path do not interfere with accurate positioning of the utility.
Dual-Spars are better able to characterize the expected circular model of the magnetic field arising from a current applied to deep directionally bore lines. The method uses simultaneous field measurements from both spars and is a generalization of the simple ratio measurement that handheld locating tools make at the peak signal (top of the circle). An advantage of the new approach is that the accuracy of the estimates (statistical confidence) is computed based on the non-circularity of the measured field. Systems that rely on a simply ratio measurement cannot provide error estimates with the 3D position and therefore have been utilized primarily as 2D location tools.