Data Sharing:-The National Pipeline Mapping System
Kandice A. O'Malley
Area Manager, AM/FM/GIS, Coler & Colantonio, Inc.
16360 Park Ten Place, Suite 215
Houston, Texas 77084
Historical Perspective
With the continuing advancement of technology evolution, geospatial information, its
benefits and power, are becoming a critical part of mainstream business strategy in
multiple sectors. In 1995, the United States Department of Transportation Office of
Pipeline Safety initiated a program to map all major pipelines in the continental United
States to assist their efforts in regulatory oversight of these facilities.
A team was assembled consisting of representatives from both industry and various state
and federal regulatory agencies to negotiate a fair and equitable program to meet the
needs of the regulatory agencies. The result of this ground-breaking cooperative effort
between government and industry was the design and implementation of the National
Pipeline Mapping System.
This program was initiated and tied into to several state run programs (e.g. Texas,
Louisiana, Oklahoma, Minnesota, California), already in process. As more and more
governmental agencies begin to accumulate significant data, the desire and feasibility of
sharing this data becomes a reality.
Once the information is provided to an authorized government agency, it most often
becomes what is known as "public information" and available to interested parties under
the Freedom of Information Act.
Pipeline companies may want to acquire much of this data as part of their business
strategy in the de-regulated environment. Other state and local governments may want to
obtain and offer different data layers to assist in infrastructure planning, public safety
monitoring, as well as a variety of other planning and analysis functions. The data can be
most helpful with a myriad of analysis and planning activities as long as the quality and
content of the data is taken into account.
'Accuracy' is a relative term
Since the inception of geospatial technologies the accuracy of the positional information
contained in them has been extremely subjective. Each system, each organization
mapped data to their individual requirements. In order to effectively utilize any data set
that is acquired, meaning it did not originate within your organization, it is imperative to
discover as much as possible about the origins and maintenance history of that
information.
There may be some feeling that these concepts are plebeian and obvious. There is
significant anecdotal evidence that in the realm of geospatial data management of
corridor data elements these are not so obvious and widely understood.
For this reason metadata is a requirement for submissions to the National Pipeline
Mapping System. A simplified version of the FGDC metadata standards were used.
Many expressed great difficulty with the concept of metadata. If one ever was inflicted
with a really poor data conversion from an external source, it would create a zealous
metadata convert. Metadata simply provides the "content label" for the data set - what is
in it, when it was created, how was it created, etc.
When dealing with a data set that was created and maintained by another organization or
group, it is critical to learn as much as possible about the history of that data. It also
provides a modicum of protection for the provider of the data set should the data become
corrupted during the conversion and/or import process. If the appropriate details are
documented in the metadata, it limits the responsibility of the source.
There are some considerations that may or may not be obvious from metadata content,
such as some of the early software platforms did not facilitate floating point double
precision mathematics in their software. This means that you could potentially inherit a
data set with rounding errors in the coordinate data. These rounding errors can
compound, dependent upon the number of times the positional data has been moved,
recalculated or re-projected.
If you receive a data set that was created and maintained in this system, you would need
to be aware of the creation process and maintenance history with regard to this data, if
you can possibly obtain this type of detailed information regarding your source files.
Project and Re-Project
A surprising number of people in the business of managing geospatial data sets have
come to it via very indirect paths. This means that they may not have been afforded the
benefit of training and exposure to the concepts of cartography and map projections.
There are at least 60 different commonly used map projections for North America, each
with its own idiosyncrasies and drawbacks. Some organizations do research to determine
the best map projection for their data, which can result in a projection that may or may
not be in common use.
With the volatile business environment, businesses merging, buying, divesting; this
necessitates the import and recalculation of geospatial data sets from various business
units into a cohesive, consistent database for the enterprise.
Certain popular calculators provided to translate coordinate systems and provide new
values in a different map projections, have been found to have intrinsic errors with
respect to certain map projections. In other cases, not all of the critical information was
provided to the algorithm to complete the translation correctly such as a custom min/max
value and design plane centroid value. This may not be apparent or even known about
the data, but it is wise to keep in mind if the resulting locations of your import process are
suspicios.
Errors may also be promulgated through the process of unloading data from one platform
and importing into another. The mathematics may not be consistent throughout the
process.
