ACSM.NET - LOCATION AND MONUMENTATION OF STATE CENTERS

National Geodetic Survey	American Congress on Surveying and Mapping
National Society of Professional Surveyors	American Association for Geodetic Surveying

PROPOSAL: LOCATION AND MONUMENTATION OF
STATE CENTERS OF POPULATION USING GPS

The U.S. Census Bureau recently completed the compilation and analysis of the 2000 decennial census data. From these data, they have computed the Center of Population for the United States, and the population centers of each state and the District of Columbia. This event provides an opportunity to showcase improvements in GPS technology, the adaptation of that technology by surveyors, and the ability to develop cooperative initiatives between the private sector, Federal, state and local surveying and mapping professionals.

The National Geodetic Survey (NGS), in cooperation with the individual state professional surveying associations, the American Congress on Surveying and Mapping (ACSM), the National Society of Professional Surveyors (NSPS), and the American Association for Geodetic Surveying (AAGS) would like to encourage the setting of a commemorative geodetic control monument at or near the computed location of each states' population center (hereafter referred to as the "Center Station") as determined by the U.S. Census Bureau and listed in Attachment A.

For this project, NGS has streamlined the process of adding information into the National Spatial Reference System (NSRS) by providing the guidelines listed below. Under this arrangement, the local organizing group need only perform those observations necessary to ensure the Center Station achieves a positional accuracy of 1-2 cm horizontally relative to the network of Continuously Operating Reference Stations (CORS) and/or High Accuracy Reference Network (HARN) stations. In the majority of cases the Census location will probably fall at a location that for a variety of reasons would not be a good location to establish a geodetic control point. A nearby location that is suitable for GPS measurements, and will be easily accessible to the public should be chosen instead. This project should be viewed as both a technical and a media event to highlight the achievements of Surveyors, Geodesist, and Geographers. Organizing groups are encouraged to include media contacts as part of their activities.

Site selection and mark setting requirements

The site selection should conform to the following criteria as much as possible

1. As close to the computed coordinate as possible
2. A "GPS-able" site (e.g., clear of obstructions 15° above the horizon)
3. Located on a publicly accessible site (e.g., town park, road right of way, etc.)

Once a suitable location has been selected for the Center Station, the mark should be set in accordance with "General Specifications for Aeronautical Surveys," Attachment 7-9 as listed at http://www.ngs.noaa.gov/AERO/Supinst.html

Given the unique nature of this project, it is recommended that a special commemorative mark be produced of at least 8" in diameter. The mark can have whatever logo or design the organizing committee decides. NSPS and Berntsen International www.berntsen.com have designed a disk that can be used. The design and contact information is provided in the attached information package. The costs of the survey mark will be the responsibility of the State Survey Society/Association

GPS equipment and observation requirements

All observations must be performed using dual-frequency, full-wavelength GPS receivers. All antennas must be of a make and model that have been calibrated by NGS - see: http://www.grdl.noaa.gov/GRD/GPS/Projects/ANTCAL/

Fixed height GPS tripods (quadpods) are highly recommended, but not required. If fixed height poles are not used, special effort should be made to ensure an accurate height of the GPS antenna is measured at the start and end of each session. These measurements should be recorded and diagramed on the "Illustration for Antenna Height Measurements" page of the GPS observation log sheet describes below.

GPS network design will include 3 CORS and/or HARN stations. If there are 3 CORS within 300 km, then there is no requirement for connections to HARN stations. However, it is recommended that at least 1 HARN and 1 North American Datum of 1988 (NAVD 88) bench mark (BM) published by NGS and within 50 km also be observed. If convenient the HARN station and the BM should be the same station.

GPS observation at the Center Station will consist of 3 each 5.5 hour sessions, with the start time of one session offset from the other 2 by at least 4 hours. Sessions do not all need to be on separate days. (i.e., 2 sessions can be on the same day).

If there are not 3 CORS within 300 km, then the observations at the HARN station(s) should be coincident with all Center Station observations. If a separate BM tie is performed it should be at least a single 4 hour session coincident with the observations at the Center Station. It is recommended but not required that there be 2 each 4 hours sessions to the BM. A separate NGS GPS observation log sheet, visibility obstruction diagram and station description/recovery form must be completed for each station in the project. GPS observation log sheets must be completed for each session. Copies of all forms can be found at: http://www.ngs.noaa.gov/PROJECTS/FBN/

Data processing requirements

Data at all stations should be processed through the OPUS GPS processing website: http://www.ngs.noaa.gov/OPUS/index.html

Deliverables

For the data to be "Blue-Booked", the following data must be submitted to NGS

All data should be sent to:

David Doyle
National Geodetic Survey, N/NGS2
1315 East-West Highway, #8826
Silver Spring, MD 20910
(301) 713-3178
E-mail: Dave.Doyle@noaa.gov

                     ATTACHMENT A

       Population and Population Centroid by State: 2000

FIPS Name               Population    Latitude     Longitude

01   Alabama               4447100    33.001471   -86.766233
02   Alaska                 626932    61.288254  -148.716968
03   Arizona               5130632    33.373506  -111.828711
04   Arkansas              2673400    35.080251   -92.576816
06   California           33871648    35.458606  -119.355165
08   Colorado              4301261    39.500656  -105.203628
09   Connecticut           3405565    41.494852   -72.874365
10   Delaware               783600    39.397164   -75.561908
11   District of Columbia   572059    38.910092   -77.014001
12   Florida              15982378    27.795850   -81.634622
13   Georgia               8186453    33.332208   -83.868887
15   Hawaii                1211537    21.146768  -157.524452
16   Idaho                 1293953    44.242605  -115.133222
17   Illinois             12419293    41.278216   -88.380238
18   Indiana               6080485    40.163935   -86.261515
19   Iowa                  2926324    41.960392   -93.049161
20   Kansas                2688418    38.454303   -96.536052
21   Kentucky              4041769    37.808159   -85.241819
22   Louisiana             4468976    30.699270   -91.457133
23   Maine                 1274923    44.313614   -69.719931
24   Maryland              5296486    39.145653   -76.797396
25   Massachusetts         6349097    42.271831   -71.363628
26   Michigan              9938444    42.866412   -84.170753
27   Minnesota             4919479    45.210782   -93.583003
28   Mississippi           2844658    32.566420   -89.593164
29   Missouri              5595211    38.437715   -92.153770
30   Montana                902195    46.813302  -111.209708
31   Nebraska              1711263    41.183753   -97.403875
32   Nevada                1998257    37.165965  -116.304648
33   New Hampshire         1235786    43.153046   -71.463342
34   New Jersey            8414350    40.438458   -74.428055
35   New Mexico            1819046    34.623012  -106.342108
36   New York             18976457    41.507548   -74.645228
37   North Carolina        8049313    35.553334   -79.667654
38   North Dakota           642200    47.375168   -99.334736
39   Ohio                 11353140    40.480854   -82.749366
40   Oklahoma              3450654    35.597940   -96.834653
41   Oregon                3421399    44.732273  -122.579524
42   Pennsylvania         12281054    40.463528   -77.075925
44   Rhode Island          1048319    41.753318   -71.448902
45   South Carolina        4012012    34.034551   -81.032387
46   South Dakota           754844    44.047502   -99.043799
47   Tennessee             5689283    35.795862   -86.397772
48   Texas                20851820    30.943149   -97.388631
49   Utah                  2233169    40.438987  -111.900160
50   Vermont                608827    44.081127   -72.814309
51   Virginia              7078515    37.750345   -77.835857
53   Washington            5894121    47.341728  -121.624501
54   West Virginia         1808344    38.767195   -80.820221
55   Wisconsin             5363675    43.728544   -89.001006
56   Wyoming                493782    42.675762  -107.008835

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