Underground Construction - March 2019 - 20

Utilizing Inertial Navigation Technology
for 3D Mapping, Locating, Management

FR S IT
L O O K

Otto Ballintijn, Reduct
and Santosh Saride,
Condux International

Over the last two decades, significant advances have been made
in the quality and application of
inertial navigation technology
targeted at mapping underground pipe and duct assets.
This article provides information
on pipeline technologies that are
available to map a minimum internal diameter (ID) of 1.6-inch
to larger sizes. The pipeline mapping system offers a range of

MARCH 2019 | UConOnline.com

solutions that can map any pipe,
regardless of its material, depth
or type of utility.
Location, location, location ...
is the primary concern when it
comes to underground infrastructure operations, maintenance and rehabilitation. Most
pipeline operators are investing heavily in state-of-the-art
geographic information systems
(GIS) to store network-related
data, including XYZ.
However, the quality of XYZ
data populated from a GIS platform is often inaccurate or inadequate due to:
* Aging or lacking information
* Unknown depth
* References to no-longer-existing, above-ground landmarks
* Original data is non-digital
* Use of a multitude of scales
and coordinate systems,
making exchange of data
very inefficient
* Inability to map infrastructure
installed by means of trenchless
methods, such as river crossings, underneath buildings, etc.
The risk is, therefore, high
that costly GIS platforms become
populated with inaccurate and
low-value XYZ data, yet the val-

ue of a GIS platform is directly
related to the quality of the data
contained in it.
The main problem is often
that there is no accuracy label
attached to data stored in GIS
platforms and, as a result, the
quality of data is reduced to the
lowest-common denominator.
Low-accuracy data significantly increases the risk of future
damage.

Inertial navigation
technology
Traditionally, inertial navigation
was developed for the airline,
marine and defense industries,
but today can be found in applications such as GPS systems and
smart phones.
Inertial Navigation Probes typically contain a range of inertial
sensors such as gyroscopes, accelerometers and magnetometers.
The object of an inertial navigation probe is to frequently measure the angular rate of change of
its core axis; i.e. changes in heading (azimuth), pitch (inclination)
and roll. Distance is measured to
give length to the resulting vector angles so that a three-dimensional profile can be created.

DuctRunner-technology-based probes operate autonomously, as there is no tethered
data cable or surface tracing
required. As a result, pipes and
ducts can be mapped to any
depth and may cross any terrain.
Measurement accuracy is dependent on several factors.
First and foremost is the
quality of the probe and data
processing software. Second, the
better the probe is aligned inside
the pipe, the more accurate the
result. Centralizing spacers are
recommended to obtain optimal
alignment but are not always operationally possible. For example,
an aging wastewater pipe tends
to have many ill-fitting lateral connections and joints that
may hinder the centralizers from
passing smoothly. In such cases,
it is operationally more efficient
to run the probe along the invert
of the pipe.
A third factor affecting accuracy is the skill of the operational
team. Pipeline mapping systems
have many built-in algorithms to
detect errors and inconsistencies,
but it is up to the operators to
follow the recommended procedures and assess the logged data.

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Underground Construction - March 2019

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