The Definition of "Graphic MSAG"
Putting the Pieces Together
By Jerry W. Merlick, Contact One Inc.
As if we need additional acronyms or catchy terminology for
defining the latest and greatest that technology has to offer,
there is a new buzzword in the 9-1-1 field. Recent 9-1-1 related
documentation out of California and Texas has referred to
it. Marketing material makes occasional mention of it. Public
safety conferences will have more and more presentations on
the topic as well. What is the term? This term is "Graphic
MSAG". As with most new technology or software solutions,
there tends to be a wide range of opinions regarding what
a general consensus for a definition may actually be. The
true meaning can vary from the over simplified to the uninformed.
While wireless 9-1-1 has been the focus of much attention
in 9-1-1 for the last few years, the MSAG database remains
a vital piece to the 9-1-1 puzzle. The purpose of this article
is to provide a clear definition and meaning of the term "Graphic
MSAG".
In order to articulate a valuable definition, some groundwork
must be laid. This groundwork involves understanding the definition
of the words that compose the phrase "Graphic MSAG".
Because the term to be defined has a word which relates to
location, i.e. "graphic", mapping is certainly related
to the definition of the term. For this reason, the graphic,
or mapping portion of the term "Graphic MSAG" refers
to the use of Geographic Information Systems, also known as
GIS. As defined by GIS.com:
"A GIS combines layers of information about a place
to give you a better understanding of that place."
As most in the field of 9-1-1 know, GIS is also referred
to as mapping, and has become a critical piece of the 9-1-1
puzzle. While the word graphic implies mapping,
one must remember that GIS is a powerful and complex system
that allows one to store, manage, and maintain geographically
related information in relational databases. This information
can also be displayed as a map. Without GIS, telecommunicators
would have a difficult time with identifying the locations
of wireless callers or performing other critical real-time
PSAP tasks.
Another piece of the puzzle is the MSAG, also known as the
Master Street Address Guide. As defined by NENA 01-002 Master
Glossary 02-03:
"[The MSAG is] a data base of street names and house
number ranges within their associated communities defining
Emergency Service Zones (ESZs) and their associated Emergency
Service Numbers (ESNs) to enable proper routing of 9-1-1
calls."
The MSAG database is completely based on locations and addresses.
As a computer file, the MSAG is similar to an electronic spreadsheet,
in that, this database has no picture to go with it such as
a map. This is where the power of the GIS is applied. Because
streets, addresses, ESNs, and many other aspects of
the typical E9-1-1 operations are all based on geography,
using GIS to provide analysis of the MSAG makes sense.
Through the combining of mapping (GIS) and one of the 9-1-1
databases used by the telephone companies (MSAG), there is
the convergence of the two databases into a single usable
system. While the initial synchronization of the GIS and MSAG
is critical, the continued and integrated maintenance
of these two databases is the ultimate purpose of the Graphic
MSAG. This concept is one of the most important for readers
to grasp that two independent databases, properly managed,
can now essentially continue to remain as one.
Traditional MSAG / GIS Data Model
Traditionally, the MSAG and GIS have both resided, and have
been maintained independently of each other. This approach
is unnecessarily time-consuming because the MSAG and GIS databases
are redundantly managed. Also, this model has potential for
errors being made between the two databases. For most 9-1-1
agencies, the MSAG essentially drives the maintenance
process. Addresses for new telephone service may be requested
that fall outside a range in the MSAG, at which point the
MSAG coordinator is notified. He or she researches the problem
and decides whether to update the MSAG to accommodate the
new address, or to tell the Telco that the address cannot
be accepted. Meanwhile and outside of what is occurring with
the MSAG, the GIS editor may be adding streets and updating
addressing as changes are relayed from planning agencies and/or
addressing authorities.
This model would be fine if the MSAG were the end-all source
for new address assignment. However, in jurisdictions, new
addresses are assigned at a city or county agency such as
the Planning Department, Assessors Office or Addressing Enumerator.
Such changes to street names and addressing are sometimes
not transmitted to the MSAG coordinator, resulting in the
MSAG disagreeing with the legal addressing in a jurisdiction.
Sometimes, the MSAG coordinator has limited contact with the
GIS editor. In addition and in most cases, the MSAG coordinator
does not make the GIS editor aware of the MSAG changes in
a timely manner, if at all. When these two do communicate,
the very nature of the MSAG is so different from the GIS that
full synchronization of the two seldom occurs in a continuous
manner. These deficiencies can cause chronic erroneous data
in the Automatic Location Information (ALI) database. The
diagram below is considered the Traditional MSAG / GIS
Data Model.

Traditional MSAG / GIS Data Model
Common Deficiencies of the Traditional MSAG / GIS Data Model:
- Address ranges of existing MSAG records are routinely
expanded in order to accommodate inaccurate house addresses
(ALI records) that are submitted by the Telco
- New misspellings of existing names are entered into the
MSAG, thus creating similar but different MSAG / GIS database
records
- Non-existent street names are added to the MSAG
- MSAG additions may be assigned an incorrect ESN
- Addresses that fall into missing blocks of street ranges
may only be discovered when someone places a 9-1-1 call
from one of those addresses
- No-Record-Found instances are more frequent
utilized at the PSAP.
In real-time use, when ALI mapping is implemented at the
PSAP(s), calls are occasionally not located on the map because
the MSAG and ALI dont correspond to the addressing that
actually exists in the community and disagrees with the GIS
data
In practical terms, the MSAG ends up determining the addressing
that is used for ALI and locating callers. The MSAG should
not be used to determine addressing. Instead, the MSAG should
be a reflection of addressing as it actually and potentially
exists. The unfortunate fate is that the MSAG almost never
conforms to this idealized goal, thus confirming the need
for a new model for maintaining MSAG and GIS data.
The Innovative MSAG / GIS Data Model
Moving away from Traditional Data Model to the
Innovative Data Model, the flow of addressing
information used for GIS and MSAG becomes fashioned after
how addressing data that is used for 9-1-1 purposes should
actually be processed. This process inverts the existing MSAG
update process by allowing the GIS to now be the catalyst
for all MSAG updates. All new addressing and street revisions
originate at the GIS and therefore the Innovative MSAG
/ GIS Data Model becomes more logical in terms of maintaining
the GIS and MSAG data.

Innovative MSAG / GIS Data Model
Automatic MSAG Updates
The concept of allowing the GIS to perform MSAG edits is
quite simple. Essentially, a user makes a change in the GIS
and the GIS generates an electronic change request to the
MSAG database. The change request is automatically generated
when one or more edits to the GIS data are completed, and
the user submits these edits to the MSAG database. Examples
of MSAG change requests may be an address range change on
an MSAG record, a completely new street record entry with
corresponding address ranges and ESNs, or an ESN change on
a selected set of streets. The use of a GIS to perform these
edits allows for users to visually adjust the streets
and ESN boundaries, or create new streets while accurately
updating the MSAG database. In addition to updating the MSAG
automatically, the GIS can perform spatial or location data
analysis and correction which cannot be performed without
the use of GIS. A very few examples of these GIS spatial processes
include:
- Street directions are incorrect
- Address ranges have inconsistencies
- ESN boundaries have problems
- Parity Errors regarding ODD and EVEN address values exist
Through using a GIS to maintain the mapping data as well
as the MSAG, considerable resource savings is immediately
recognized. These savings include the following:
- Make edits for two databases from one entry point update the map and update the MSAG
- Perform the work of both an MSAG Coordinator and a GIS
Analyst through one computer software interface
- Reduce the amount of time required to maintain the 9-1-1
database
According to Susan MacFarlane, 9-1-1 Coordinator of Maricopa
County Region 9-1-1, the benefit of using a Graphic MSAG is
substantial. This is due to the size of the Maricopa County
Region 9-1-1 and the corresponding large amount of data to
manage. The county 9-1-1 jurisdictional area includes well-known
cities such as Phoenix, Scottsdale, Tempe and Mesa.
"The Phoenix Metro area is one of the fastest growing
areas of the country. Like many governmental agencies, we
face limited resources to do the constant maintenance needed
for the MSAG and GIS. The ability to streamline the process
so that we can make the best use of personnel means a better
MSAG, a better GIS, and the ability to provide better service
to the citizens in our community."
The Bottom Line
While saving time and money is always important for the maintenance
of the data, the absolute biggest payoff of a true Graphic
MSAG is the creation and maintenance of highly accurate GIS
and 9-1-1 data. More accurate data is directly related to
more quickly locating 9-1-1 callers and reducing response
time to those callers. The most important and critical benefits
from the use of a Graphic MSAG are the following:
- Faster response time to 9-1-1 callers
- More accurate mapping data
- More accurate 9-1-1 data: MSAG and ALI
- Real-time and up-to-date MSAG changes
- Substantial return on investment through
- Cost savings
- Time savings
- Better use of personnel
- The processing of one or more records at one time
- A true Graphic MSAG
Marc Berryman, Director of GIS for Greater Harris County
9-1-1 Emergency Network located in Houston, Texas agrees with
the benefits of a Graphic MSAG. By implementing a Graphic
MSAG in his department he believes the benefits will be realized
immediately and across the public safety enterprise. During
a recent discussion on the subject, Mr. Berryman stated the
following:
"By employing the model of a Graphic MSAG, also
referred to as a Spatial MSAG, it reduces
possible errors, and ensures the MSAG and GIS data are
always synchronized. When this happens, 9-1-1 telecommunicators
can work more efficiently, "No Record Found"
errors are reduced, and the needs of public safety are
better met."
The bottom line is to meet the public safety
needs in order to save life and property. Joining the two
previously independent databases guarantees a positive advantage
because there is a greater purpose no only to each database,
but to the public safety institution as well. Each piece contributes
as much or more to the other in order to create a database
checks-and-balances system. Because locations and street address
information is central to the GIS and the MSAG databases,
the two can leverage one anothers information and the
results are more accurate data and better response to emergencies.
In addition, the addressing and location information originates
at the GIS, which is precisely where the point of origin lies.
For these and the many reasons provided, a Graphic MSAG is
a critical and needed solution to the 9-1-1 database puzzle.
If the solution was not ultimately about responding to 9-1-1
callers more quickly, the benefits would be far less effective
and the justification limited.
About the author
Jerry W. Merlick is the president of Contact One, Inc. providing
leading-edge 9-1-1 GIS software including a graphic MSAG product,
9-1-1 GIS software and related services to 9-1-1 agencies.
He can be reached at 512-459-4636 or email
us.
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