A proposal for a National Spatial Data Infrastructure Standards Project

PROJECT TITLE: Standard for a United States National Grid for Spatial
Addressing

DATE OF PROPOSAL: May 24, 1999 with addendum of May 3, 2000.

TYPE OF STANDARD: A data presentation standard specifying the
representation of two-dimensional spatial addresses.

SUBMITTING ORGANIZATION:

The Public X-Y Mapping Project

8013 Hatteras Lane

Springfield, VA 22151

Grid: 18SUH06949701 (NAD 83)

POINT OF CONTACT:

N.G. \`\`Tom\'\' Terry, Jr.

The Public X-Y Mapping Project

E-mail: terryme@erols.com

Pager: 703-457-0451

OBJECTIVES: The objectives of this standard are to provide the community
with:

1.  A presentation format to enable the use of large-scale paper and
    digital maps with Global Positioning System (GPS). Persons using
    different commercial brands or types of maps will be able to
    communicate with each other because they will all use the same grid
    reference system.

2.  An unambiguous, geodetically referenced, and mathematically uniform
    system for a two-dimensional address to supplement conventional
    street addresses. It will also serve as a spatial address away from
    the road network.

3.  A single system which can be taught to all citizens in the school
    system, and which can be used in any community across the nation.

4.  A system that is seamless at political boundaries and can be
    uniformly truncated at various levels of precision.

5.  A basis for building a street and feature index database referenced
    to the USNG which can be accessed and used by any member of the
    community.

SCOPE: This standard will define a United States National Grid (USNG)
for use in spatial addressing type applications. It is intended to serve
as a preferred system that is easier to use than latitude and longitude
by the average citizen. It is intended for use in mapping at scales from
approximately 1:5,000 to 1:1,000,000. Technically, it will be the same
as the Military Grid Reference System (MGRS), taking advantage of that
public domain system\'s use of the Universal Transverse Mercator (UTM)
grid and truncation and variable precision features. It will also
incorporate where possible and appropriate use of the Federal
Information Processing Standard (FIPS) of May 28, 1987 for Codes for the
Identification of the States, District of Columbia and the Outlying
Areas of the United States, and Associated Areas. For example, the use
of these abbreviations can be used in most cases (Alaska being an
exception) as an option to replace the MGRS Grid Zone Designations,
while retaining full backwards compatibility with MGRS. The standard
will address other issues pertinent to civil mapping, such as
recommended grid spacing.

This standard is not intended to change how coordinates are stored in
computers. It is not intended to replace the use of latitude and
longitude on nautical and aeronautical charts or on maps at scales
smaller than approximately 1:1,000,000. It is not intended to replace
the State Plane Coordinate System (SPCS). SPCS will continue to be used
where jurisdictions prefer it for property descriptions, mapping at
scales larger than 1:5,000, or other more technical uses such as manual
surveying.

JUSTIFICATION/BENEFITS: Today Americans have many sources of geographic
information to support their day-to-day activities. Commercial street
and highway maps are a major source of this information for the
community. These commercial products typically carry a system of
proprietary zone grids, unique to a particular map or map brand. Zone
coordinates consist of an alphanumeric code that locates places within a
cell of a given spatial extent.

A community may have a variety of large-scale maps available that use
disparate coordinate systems. In a sample of the Washington, DC area
conducted this year, four years after the Global Positioning System
(GPS) reached full operational capability, 25 different large-scale
street maps were found to be commercially available, and on these maps,
there existed 21 different coordinate systems. Of these grids, none
worked with readily available, low-cost consumer GPS receivers. Some
commercial mapmakers claim their maps (and zone grids) are the de facto
standard in some communities, because in some cases, local governments
have adopted one of these proprietary zone grids for use as a spatial
address system.

Often organizations with a local focus have not recognized problems
inherent in the use of disparate grid systems or the need for preferred
system that is national in scope. Consumers and businesses that must
routinely cross interstate and local government boundaries require a
solution national in scope. In an emergency scenario where time is
precious and understanding communicated locations or positions in a
non-conflicting manner is critical, it is operationally best for all to
use a standard reference systems. When a local government accepts the
use of a proprietary coordinate system as a \`\`de facto\'\' standard,
it grants a monopolistic license to a specific commercial map vendor,
thereby inhibiting competition in that community\'s marketplace. The
USNG will provide commercial map vendors who choose to adopt it a
preferred coordinate system that enhances their products by enabling the
exchange of spatial address information.

Addressing Schemes

Americans have traditionally used postal or street addresses to locate a
destination in their day-to-day activities. In 30 of the 50 States, the
Public Land Survey System (PLSS) is another system often used to
describe a piece of property. Traditional addressing schemes have served
well, and will continue to be used. Nonetheless, these systems are
flawed by their lack of mathematical uniformity. Additionally, they
often lack the ability to provide an address for any point in the
nation.

These different systems do not work with GPS, or are unreliable for work
with GPS and digital maps. With the advent of GPS, the average citizen
can purchase access to a \$10 billion source of precise positioning
information for the price of a good watch. In the near future, vehicles
will routinely come equipped with GPS driven digital maps. Mobile
wireless communications have become pervasive, allowing community
members to cheaply communicate with one another from any point on he
globe. When people communicate, one of the fundamental pieces of
information they need to exchange is location. In view of these
technological advances, there exists a need to support the community in
its use and communications of geospatial information with a preferred
spatial address system.

Computer Translation versus a Preferred System

Some have suggested that because high-speed digital computers can easily
translate between mathematically uniform transformations, there is no
need for a preferred system for spatial addressing. They contend that
computer systems will simply translate a coordinate value from any one
of an infinite number of coordinate systems used by the community into
one the operator can understand or use. In the real world, this is a
flawed concept. First, it will be some time before every citizen has a
lap/palm top computer to use for routine navigation. Secondly, it will
not be possible to keep every citizen\'s computer updated with the
infinite number of coordinate systems that can be produced. It is
analogous to cartographic anarchy, where there are no recognized
conventions.

Some say the day of the paper map is over, but we have not achieved the
\`\`paperless environment.\'\' Paper will continue to be a critical
medium for portraying and using geospatial information. While digital
systems information such as GPS, the Internet, and print on demand paper
maps will increase the ability of the community to use geospatial data,
paper maps will continue in widespread use. Maps required a common
coordinate system if people are to exchange useful positioning
information. A preferred spatial addressing convention is required just
as a preferred set of street names is used for street addresses. Street
addresses simply would not be useable if there were multiple names for
each street. Accordingly, a preferred convention is necessary if the
community is to have a useable and workable spatial address system.

Truncation and Variable Precision

The Universal Transverse Mercator (UTM) system most closely meets USNG
requirements and is:

-   A plane coordinate system, which is far easier to use than latitude
    and longitude for large-scale work.

-   A geodetically referenced, mathematically uniform system in the
    public domain.

-   National and international in scope.

However, UTM does not provide a convention for truncating coordinate
values, nor does it allow for variations in precision of information.
For example, although the USNG will support 1-meter precision, many
users do not need spatial resolutions finer than 10 meters for location
and navigation and do not require that coordinates be shown to all the
decimal places to which they are stored in computers. In fact, users
find it easier to remember fewer digits. This is analogous to memorizing
and recalling telephone numbers.

The Military Grid Reference System (MGRS) is a mature, widely used,
off-the-shelf system based on the UTM that also provides a method to
truncate coordinates and offers various levels of precision. It is
proposed that the USNG use this existing technical standard.

DEVELOPMENT APPROACH: This standards development effort will make use of
existing standards and specifications to the greatest possible extent.
The MGRS meets the basic requirements for a USNG. The Public X-Y Mapping
Project has nearly completed a draft of the proposed USNG that will be
presented to the FGDC as a starting point for development of this
standard. It is proposed that the FGDC form an ad hoc working group or
subgroup of the Standards Working Group to review The Public X-Y Mapping
Project Draft and prepare it for public review. The need for a more
permanent group will be reevaluated based on initial public comment.

Implementation and acceptance of a preferred spatial addressing standard
will require demonstration of the usefulness of the standard. Therefore,
there is a need to plan and carry out demonstration projects once the
technical specification has stabilized.

DEVELOPMENT AND COMPLETION SCHEDULE:

Completion of initial draft: August 1999.

Public Review: September-November 1999.

Final Draft: TBD\--dependent on public comment\--December 1999.

Demonstration Projects: 2000-2003.

RESOURCES REQUIRED: A working draft of the USNG will be provided by The
Public X-Y Mapping Project. No new resources are needed to prepare the
working draft. An ad hoc working group of the Standards Working Group
will be needed to assist The Public X-Y Mapping Project in preparing the
draft for public review according to FGDC directives. The Public X-Y
Mapping Project expects this group to assist in the adjudication and
resolution of comments received during the public review.

Administrative and financial resources will be required from FGDC
members and outside organizations to carry out the demonstration
projects.

POTENTIAL PARTICIPANTS

-   Major Federal land map producers.

-   Commercial map producers.

-   The GPS industry.

-   Representatives of map users such as E-911 service providers (see
    examples).

RELATED STANDARDS: This proposal relates to:

-   ANSI X3.61-1986, Representation of Geographic Point Locations for
    Information Interchange, which standardizes representation of UTM
    coordinates for computer representation, since the proposed USNG is
    based upon the UTM.

-   ISO 15046-16, Positioning Services, which provides an interface for
    real-time GPS receiver output (and output from other positioning
    technologies). The USNG standards project should follow the progress
    of ISO/TC 211 Work Item 16 and harmonize with the requirements of
    ISO 15046-16.

-   ISO 15046-11, Spatial Referencing by Coordinates, which provides a
    conceptual schema for the description of coordinate reference
    systems. The USNG standards project should follow the progress of
    ISO/ TC 211 Work Item 11 and harmonize with the requirements of ISO
    15046-11.

It is not clear how this proposal relates to the linear referencing
standard being proposed by the Intelligent Transportation community in
the U.S. and the U.S. representatives to ISO/TC 204, the international
road informatics standards committee. This will be investigated during
the preparation of the public review draft.

This proposal may be related to the NSDI Framework Transportation
Identification Standard being developed by the FGDC Ground
Transportation Subcommittee. Overlaps will be investigated during the
preparation of the public review draft.

The USNG standard will be drawn from NIMA Technical Manual (TM) 8358.1,
Datums, Ellipsoids, Grids, and Grid Reference Systems, which describes
the basic principles of the Military Grid Reference System.

OTHER TARGETED AUTHORIZATION BODIES: If it is determined that this
standard could benefit from or would require changes to ANSI X3.61, then
NCITS L1 (custodian of ANSI X3.61) would be another target organization.

Although initially targeted for adoption in this country, the USNG could
be applied worldwide. If this is determined to be desirable, ISO/ TC 211
would the appropriate standards body to consider it.

Addendum\--Example Applications of the USNG

USNG is intended to be preferred method for designating point positions
for numerous activities, particularly vehicle/land navigation. It will
supplement conventional street addresses in the community and will
provide a virtual address for any point away from the road network.

1.  Enhanced 9-1-1 The spatial address (in the form of USNG coordinates)
    will appear along with the caller\'s street address on the screen of
    9-1-1 system operators in Public Safety Access Points (PSAP). The
    USNG address can be used by officers on the street, who may be
    equipped with either paper or digital maps.

2.  Disaster Relief Operations In the aftermath of Hurricane Andrew, the
    devastation was so great, that street signs were blown away, making
    it difficult for outside agencies to navigate to places in need of
    assistance. USNG will provide a nationally uniform method for
    describing a position that will allow outside assistance providers
    to \`\`hit the ground running\'\' with GPS equipment and to make use
    of commercial street maps that may be readily available.

3.  Search and Rescue (SAR) The advent of technologies such as medical
    evacuation helicopters and wireless communications (i.e. radios,
    cellular phones) has increased the need to precisely and
    unambiguously identify places away from the road network. For
    example, medical evacuation helicopter crews have cited difficulties
    (while often flying in dangerous environments, i.e. mountainous
    terrain at night) in understanding SAR team descriptions of where
    they are supposed to fly. A preferred spatial address system would
    eliminate this communication interoperability problem.

4.  Digital Maps Digital maps from sources such as CD ROMs for use on
    desk/laptop computers and Internet information vendors are coming
    into widespread use. The USNG has greater suitability for these
    digital mapping systems than conventional street addresses because
    it affords greater accuracy and ensures confidence that the point
    indicated is the correct location. Today, it is possible to quickly
    access a source of maps on the Internet. With a USNG spatial
    address, the user precisely designates the point of interest by
    entering the address as if it were a phone number (This has
    important implications for future cellular phone operations and
    GPS/car navigation systems). The information provider can quickly
    respond with a map of that location. The USNG also provides a
    coordinate system that can be portrayed on these maps when they are
    printed (\"print on demand\'\'), thereby ensuring a geodetic
    reference for later use of the map with GPS when driving to the
    location.

5.  Locating Small Business Features Quite often, it is necessary to
    locate a small feature such as an Automated Teller Machine (ATM),
    the drop off box for a package delivery service such as FedEx or
    United Parcel Service (UPS), or post office box. Today, automated
    sources of information provided by the Internet or by telephone
    indicate the location of the closest ATM or drop-off box, but
    finding these small features can prove to be a difficult task. USNG
    spatial addressing will greatly ease a customer\'s task by
    unambiguously communicating a point position of higher resolution
    than possible with conventional street addresses and will maximize
    current and future capabilities of GPS.

6.  Locating a Street Address Number Locating a street address number of
    buildings or homes can be a difficult task that greatly adds to the
    workload of a vehicle deliver. This is especially true at night
    during heavy traffic. Many times a driver is confounded that street
    address numbers are small, poorly placed, or missing altogether. A
    virtual address defined by USNG enables the use of GPS or a map with
    a USNG grid and greatly eases the workload of a driver trying to
    located a specific and precise location.

7.  Identifying Multiple Businesses Locations A business with multiple
    locations in a community can add the spatial address for its
    establishments in telephone or Internet directories (or other
    sources of information). This information, coupled with commercial
    street maps that portray the USNG grid, will allow potential
    customers to quickly determine which establishment is closest to
    them. Customers will easily see the relative location of each store.

8.  Outdoors Recreation A great deal of outdoors recreation, such as
    backpacking, kayaking, hunting, fishing rock climbing, cross-country
    skiing, snowmobiling, mountain-biking, and horseback riding, takes
    place away from the road network and the conventional street address
    system. The widespread availability of low cost wireless
    communications (i.e. cellular telephones, Family Radio Service
    \[FRS\] transceivers, etc.) has increased the need for a spatial
    address system that people can use to identify their location in a
    simple, uniform manner without ambiguity during these activities.
    For example, in the event of an accident requiring medical
    assistance, USNG will provide a standard method for communicating
    unambiguous location of the accident to responding organizations.
    Likewise, backpackers and others can report their USNG spatial
    address for a pickup point after a long hike, adding flexibility to
    their plans. The USNG will provide a universal means for identifying
    the location of shelters, cabins, trail heads, springs, camping
    areas, parking areas, and other features in journal entries,
    magazine articles, guide books, and other source of recreational
    information. A USNG will provide a universal coordinate system and
    grid for outdoor recreation maps, which ensures the exchange and
    compatibility of spatial address information across many different
    sources to include the use of GPS.

9.  Agriculture There is a need in agriculture to uniformly identify
    particular parcels of land for various work tasks. For example, a
    farmer communicating with a mechanic by cellular phone may need to
    clearly identify in which field a tractor has broken down. Another
    example is where the farmer has to instruct a deliverer of some
    commodity about where to stage the material.

10. Tourism The tourist is one who is new to an area and unfamiliar with
    its features, but is looking for specific places of interest. A
    preferred spatial address for a place of interest will be found on
    brochures and in other tourism information to enable tourists to
    quickly and unambiguously locate a place of interest.