What is geomapping and how is it used in trenchless technology?

Q:

What is geomapping and how is it used in trenchless technology?

A:

Underground utility networks, such as natural gas pipelines, water lines and electrical lines can consist of millions of miles piping and cable infrastructure. As these networks continue to expand, the potential for accidental damage during trenchless construction and trenchless rehabilitation increases.

As a result, accurately identifying the location of these underground utilities is a top priority in most trenchless projects. (Read Identifying and Managing Dangers Associated with Subsurface Utilities.)

While most state laws require that the location of all buried utilities be documented and kept on file, there are instances where some infrastructure is not mapped. Additionally, some traditional methods of locating buried pipelines have inherent positional errors, which can lead to potential construction accidents.

Many modern trenchless construction and rehabilitation projects use geomapping to determine the precise position of subsurface utilities. This technique involves using GPS technology combined with radio waves to accurately create “As-built” maps that closely match the actual utility location.

Geomapping is the process of overlaying raw data onto a digital map. It allows trenchless operators to visualize the location of underground utilities with respect to other features, such as roads, buildings, rivers, existing pipelines, etc..

During trenchless projects, geomapping is usually done by combining the following technologies:

Usually, the CCTV vehicle, which is equipped with the sonde (transmitter), is launched into existing underground pipelines via small excavations known as entry pits. The vehicle traverses the length of the pipe while transmitting electromagnetic signals which are received by a walkover locator.

Once the locator determines the location of the pipe, a GPS mapping stick (or another similar device) collects the precise location coordinates. The data gathered from the GPS is stored in a Geographic Information System (GIS) master database.

Geomapping software can then be used to overlay the GPS coordinates on various digital maps. One of the main benefits of using geomapping is its ability to store and retrieve utility location information almost instantaneously. Additionally, future data can be added to the GIS database to continuously update and improve the quality and accuracy of existing information.

With the information stored in an electronic database, contractors can easily access highly accurate utility location data for all present and upcoming trenchless construction projects.

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Written by Krystal Nanan
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Krystal is a civil engineer and project manager with an MSc in Construction Engineering and Management. Her experience includes the project management of major infrastructure projects, construction supervision, and the design of various infrastructure elements including roadway, pavement, traffic safety elements and drainage.

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