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National Readjustment of NAD 83
Indiana Society of Professional Land SurveyorsIndianapolis, IN
January 18, 2008
NATIONAL SPATIAL REFERENCE SYSTEM(NSRS)
Consistent National Coordinate System
• Latitude • Longitude
• Height • Scale
• Gravity• Orientation
and how these values change with time
ACRONYMS US
NATIONAL SPATIAL REFERENCE SYSTEM
North American Datum of 1983 (NAD 83)North American Vertical Datum of 1988 (NAVD 88)
First civilian datums designed to be consistent with space-based observations (GPS)
First civilian datums to be best-fitting globally not locally
First geodetic reference systems to be Accessible through Continuously Operating Reference Stations (CORS) and derived products
First geodetic reference systems to be available free from WWW
Only reference system to freely integrate data fromoutside sources
MULTIPURPOSE – Supports Geodesy, Geophysics, Land Surveying, Navigation, Mapping, Charting and GIS
ACTIVE – Accessible through Continuously Operating Reference Stations (CORS) and derived products
• A horizontal datum is the coordinate system that we use to locate ourselves on the earth– Involves the origin and orientation of
coordinate axes • geocentric cartesian (X,Y,Z)• Usually the origin is near the center
of mass of the earth• one axis intersects the earth’s
surface at the intersection of the prime meridian and the equator
– and a reference ellipsoid• Latitude Longitude and height• Specific geodetic datums are usually
given distinctive names. – North American Datum of 1983, – International Terrestrial
Reference Frame (YYYY)– WGS84
Horizontal DatumsHorizontal Datums
+Z
-Y
+X
XY
Zb
a
H
Cartesian systemX = -2691542.5437 mY = -4301026.4260 mZ = 3851926.3688 m
Lat Lon = 37o 23’ 26.38035” N = 122o 02’ 16.62574” W
H = -5.4083 m
GEODETIC DATUMS
Classical
Horizontal – 2 D (Latitude and Longitude) (e.g. NAD 27, NAD 83 (1986)) Vertical – 1 D (Orthometric Height) (e.g. NGVD 29, NAVD 88)
Contemporary
PRACTICAL – 3 D (Latitude, Longitude and Ellipsoid Height) Fixed and Stable – Coordinates seldom change (e.g. NAD 83 (1996) or NAD 83 (NSRS 2007))
SCIENTIFIC – 4 D (Latitude, Longitude, Ellipsoid Height, Velocity) –
Coordinates change with time (e.g. ITRF00, ITRF05)
HORIZONTAL DATUMS
8 Constants 3 – specify the location of the origin of the coordinate
system.
3– specify the orientation of the coordinate system.
2 – specify the dimensions of the reference ellipsoid
b
a
N
UNITED STATESELLIPSOID DEFINITIONS
CLARKE 1866 a = 6,378,206.4 m 1/f = 294.97869821
GEODETIC REFERENCE SYSTEM 1980 - (GRS 80)a = 6,378,137 m 1/f = 298.257222101
WORLD GEODETIC SYSTEM 1984 - (WGS 84) a = 6,378,137 m 1/f = 298.257223563
BESSEL 1841 a = 6,377,397.155 m 1/f = 299.1528128
International Earth Rotation and Reference System Service
(IERS)(http://www.iers.org)
The International Terrestrial Reference System (ITRS) constitutes a set of prescriptions and conventions together with the modeling required to define origin, scale, orientation and time evolution
ITRS is realized by the International Terrestrial Reference Frame (ITRF) based upon estimated coordinates and velocities of a set of stations observed by Very Long Baseline Interferometry (VLBI), Satellite Laser Ranging ( SLR), Global Positioning System and GLONASS (GNSS), and Doppler Orbitography and Radio- positioning Integrated by Satellite ( DORIS).
Plate tectonics is accommodated giving each coordinate a velocityPlate tectonics is accommodated giving each coordinate a velocity
ITRF89, ITRF90, ITRF91, ITRF92, ITRF93, ITRF94, ITRF95, ITRF96, ITRF97, ITRF2000, ITRF2005
International Global Navigation Satellite Systems Service (IGS)
International Laser Ranging Service (ILRS)
International Very Long Baseline Service (IVS)
International DORIS Service (IDS)
International Terrestrial Reference Frame4 Global Independent Positioning Technologies
DATUM = WGS 84(G730)5 USAF GPS Tracking Stations5 DMA Evaluation Stations Datum redefined with respect to the International Terrestrial Reference Frame of 1992 (ITRF92) +/- 20 cm in each component (Proceedings of the ION GPS-94 pgs 285-292)
DATUM = WGS 84(G873)5 USAF GPS Tracking Stations7 NIMA Evaluation Stations Datum redefined with respect to the International Terrestrial Reference Frame of 1994 (ITRF94) +/- 10 cm in each component (Proceedings of the ION GPS-97 pgs 841-850)
DATUM = WGS 84RELEASED - SEPTEMBER 1987BASED ON OBSERVATIONS AT MORE THAN 1900 DOPPLER STATIONS
DATUM = WGS 84(G1150)Datum redefined with respect to the International Terrestrial Reference Frame of 2000 (ITRF00) +/- 2 cm in each component (Proceedings of the ION GPS-02) http://earth-info.nima.mil/GandG/sathtml/IONReport8-20-02.pdf
HOW MANY WGS 84s HAVE THERE BEEN????
WORLD GEODETIC SYSTEM 1984http://earth-info.nga.mil/GandG/publications/tr8350.2/tr8350_2.html
Tectonic Plates NUVEL-1A
ITRF00 vs NAD83 velocities
NAD83
Seismic cycle
• Seismic cycle consists of 2 main phases– Inter-seismic phase when
elastic strain accumulates in the crest around the fault• Strain is widely distributed
– co-seismic phase when elastic strain is converted to slip on the fault
model of the secular field
• An analytical model representing horizontal crustal motion
– Incorporates all major active faults in a single model.
– Provides a more accurate model of crustal deformation in western US
• data comprise – 4890 GPS velocities– 170 fault slip rates from
paleoseismic & paleomag studies – 258 fault slip vectors taken from
earthquakes and geologic studies
Earthquakes in Contiguous US
MEADES RANCH 1891 – KANSASOrigin for USSD-NAD-NAD27
COMPARISON OF DATUM ELEMENTS
NAD 27 NAD 83
ELLIPSOID CLARKE 1866 GRS80 a=6,378,206.4 m a=6,378,137 m 1/f = 294.9786982 1/f = 298.257222101
DATUM POINT Triangulation Station NONE Meades Ranch, Kansas Earth Mass Center
ADJUSTMENT 25k Stations 250k Stations few hundred Base lines 30k EDMI base lines
few hundred Astro Az 5k Astro Azimuths Doppler and VLBI
1.8 million observations
NAD 27 to NAD 83 (86)
Results of NAD83(86)
• Network Accuracy - 1 Meter
• Local Accuracy – First-Order (1 part in 100,000)
Second-Order (1 part in 50,000)
Third-Order (1 part in 10,000)
NAD 83(86) NETWORK PROBLEMS
NOT “GPSABLE”
POOR STATION ACCESSIBILITY
IRREGULARLY SPACED
POSITIONAL ACCURACY
HARN/HPGN ADJUSTMENT
A-Order Adjusted to VLBI-Existing FBN-CORS
B-Order Adjusted to A-Order
Existing Horizontal (Conventional & GPS) Readjusted to A/B-Order
New Adjustment Date Tag e.g. NAD83(1997)
REGIONAL CORS NETWORK
SPRINGFIELD (ILSA), ILLINOIS
_____________________________________________________________________________ | || Antenna Reference Point(ARP): SPRINGFIELD CORS ARP || -------------------------------------------------- || PID = DH3759 || || || ITRF00 POSITION (EPOCH 1997.0) || Computed in June 2005 using 14 days of data. || X = 33385.872 m latitude = 39 46 43.08683 N || Y = -4908474.031 m longitude = 089 36 37.07435 W || Z = 4059224.563 m ellipsoid height = 152.900 m || || ITRF00 VELOCITY || Predicted with HTDP_2.7 June 2005. || VX = -0.0168 m/yr northward = -0.0018 m/yr || VY = -0.0015 m/yr eastward = -0.0168 m/yr || VZ = -0.0012 m/yr upward = 0.0003 m/yr || || || NAD_83 (CORS96) POSITION (EPOCH 2002.0) || Transformed from ITRF00 (epoch 1997.0) position in Jun. 2005. || X = 33386.406 m latitude = 39 46 43.06026 N || Y = -4908475.428 m longitude = 089 36 37.05230 W || Z = 4059224.662 m ellipsoid height = 154.039 m || || NAD_83 (CORS96) VELOCITY || Transformed from ITRF00 velocity in Jun. 2005. || VX = 0.0000 m/yr northward = 0.0000 m/yr || VY = 0.0000 m/yr eastward = 0.0000 m/yr || VZ = -0.0000 m/yr upward = 0.0000 m/yr ||_____________________________________________________________________________|
ITRF00 – NAD 83(CORS96)Horiz = 0.973mEHt = 1.139m
IMPROVING POSITIONAL ACCURACY
TIME NETWORK LOCALNETWORK SPAN ACCURACY ACCURACY
NAD 27 1927-1986 10 METERS (1 part in 100,000)
NAD83(86) 1986-1990 1 METER (1 part in 100,000)
HARN 1990-1997 0.1 METER B-order (1.0 ppm) A-order (0.1 ppm)
CORS 1996 - 0.01 meter 0.01 meter
National Geodetic Survey, Retrieval Date = DECEMBER 6, 2007 KB0684 *********************************************************************** KB0684 DESIGNATION - ASSUMPTION KB0684 PID - KB0684 KB0684 STATE/COUNTY- IL/CHRISTIAN KB0684 USGS QUAD - ASSUMPTION (1982) KB0684 KB0684 *CURRENT SURVEY CONTROL KB0684 ___________________________________________________________________ KB0684* NAD 83(2007)- 39 31 12.72891(N) 089 02 56.47681(W) ADJUSTED KB0684* NAVD 88 - 196.394 (meters) 644.34 (feet) ADJUSTED KB0684 ___________________________________________________________________ KB0684 EPOCH DATE - 2002.00 KB0684 X - 81,771.588 (meters) COMP KB0684 Y - -4,926,226.861 (meters) COMP KB0684 Z - 4,037,138.456 (meters) COMP KB0684 LAPLACE CORR- -0.20 (seconds) DEFLEC99 KB0684 ELLIP HEIGHT- 164.133 (meters) (02/10/07) ADJUSTED KB0684 GEOID HEIGHT- -32.27 (meters) GEOID03 KB0684 DYNAMIC HT - 196.282 (meters) 643.97 (feet) COMP KB0684 KB0684 ------- Accuracy Estimates (at 95% Confidence Level in cm) -------- KB0684 Type PID Designation North East Ellip KB0684 ------------------------------------------------------------------- KB0684 NETWORK KB0684 ASSUMPTION 0.57 0.41 1.76 KB0684 ------------------------------------------------------------------- KB0684 MODELED GRAV- 980,049.7 (mgal) NAVD 88 KB0684 KB0684 VERT ORDER - FIRST CLASS I KB0684 KB0684.The horizontal coordinates were established by GPS observations KB0684.and adjusted by the National Geodetic Survey in February 2007. KB0684 KB0684.The datum tag of NAD 83(2007) is equivalent to NAD 83(NSRS2007). KB0684.The horizontal coordinates are valid at the epoch date displayed above. KB0684.The epoch date for horizontal control is a decimal equivalence KB0684.of Year/Month/Day. KB0684 KB0684.The orthometric height was determined by differential leveling KB0684.and adjusted in June 1991. KB0684 KB0684.Photographs are available for this station.
KB0684.The X, Y, and Z were computed from the position and the ellipsoidal ht. KB0684.The ellipsoidal height was determined by GPS observations KB0684.and is referenced to NAD 83. KB0684 KB0684.The geoid height was determined by GEOID03. KB0684 KB0684 KB0684; North East Units Scale Factor Converg. KB0684;SPC IL W - 317,315.488 796,100.180 MT 1.00005484 +0 42 40.6 KB0684;SPC IL W - 1,041,059.23 2,611,872.01 sFT 1.00005484 +0 42 40.6 KB0684;SPC IL E - 316,974.300 238,460.283 MT 1.00002161 -0 27 19.6 KB0684;SPC IL E - 1,039,939.85 782,348.45 sFT 1.00002161 -0 27 19.6 KB0684;UTM 16 - 4,376,511.174 323,870.958 MT 0.99998195 -1 18 15.2 KB0684 KB0684! - Elev Factor x Scale Factor = Combined Factor KB0684!SPC IL W - 0.99997425 x 1.00005484 = 1.00002909 KB0684!SPC IL E - 0.99997425 x 1.00002161 = 0.99999586 KB0684!UTM 16 - 0.99997425 x 0.99998195 = 0.99995620 KB0684 KB0684: Primary Azimuth Mark Grid Az KB0684:SPC IL W - ASSUMPTION 1920 TP 1976 010 03 10.2 KB0684:SPC IL E - ASSUMPTION 1920 TP 1976 011 13 10.4 KB0684:UTM 16 - ASSUMPTION 1920 TP 1976 012 04 06.0 KB0684 KB0684|---------------------------------------------------------------------| KB0684| PID Reference Object Distance Geod. Az | KB0684| dddmmss.s | KB0684| KB1363 ASSUMPTION 1920 TP 1976 APPROX. 0.5 KM 0104550.8 | KB0684| KB0685 ASSUMPTION RM 2 7.062 METERS 01146 | KB0684| KB1368 ASSUMPTION AZ A PT 1976 489.179 METERS 0994730.6 | KB0684| KB1367 ASSUMPTION AZ MK 483.552 METERS 1001424.8 | KB0684| KB1362 ASSUMPTION A PT 1976 9.725 METERS 24325 | KB0684| KB1361 ASSUMPTION MUN TANK 145.607 METERS 24654 | KB0684| CI6654 ASSUMPTION RM 21.330 METERS 26717 | KB0684| KB0686 ASSUMPTION RM 3 26.388 METERS 27304 | KB0684|---------------------------------------------------------------------| KB0684 KB0684 SUPERSEDED SURVEY CONTROL KB0684 KB0684 ELLIP H (10/15/04) 164.141 (m) GP( ) 4 2 KB0684 NAD 83(1997)- 39 31 12.72890(N) 089 02 56.47672(W) AD( ) B KB0684 ELLIP H (07/17/98) 164.137 (m) GP( ) 4 1 KB0684 NAD 83(1986)- 39 31 12.73871(N) 089 02 56.46320(W) AD( ) 2 KB0684 NAD 27 - 39 31 12.59480(N) 089 02 56.15910(W) AD( ) 2 KB0684 NAVD 88 (07/17/98) 196.39 (m) 644.3 (f) LEVELING 3 KB0684 NGVD 29 (??/??/92) 196.484 (m) 644.63 (f) ADJ UNCH 1 1 KB0684 KB0684.Superseded values are not recommended for survey control. KB0684.NGS no longer adjusts projects to the NAD 27 or NGVD 29 datums. KB0684.See file dsdata.txt to determine how the superseded data were derived.
TIME POSITIONDATUM SPAN Lat/Long/E Hgt POSITION SHIFT
USSD/NAD 1901 – 1927 39-31-12.70400 89-02-56.05500
Undetermined
NAD 27 1927 – 1986 39-31-12.59480 89-02-56.15910 4.186 m (13.73 ft)
Undetermined
NAD 83 (86) 1986 – 1997 39-31-12.73871 89-02-56.46320 8.512 m (27.93 ft)
Undetermined NAD 83 (97) 1997 – 2007 39-31-12.72890
89-02-56.47672 0.442 m (1.45 ft) 164.141
NAD 83 (07) 2007 – (?) 39-31-12.72891 89-02-56.47681 0.002 m (0.06 ft)
164.133 0.008 m (0.03 ft)
POSITIONAL CHANGESStation: ASSUMPTION (KB0684)
Reasons for Readjustment
• Multiple epoch dates• Inconsistencies between states• Need to be Consistent with CORS• Compute Network and Local accuracies• Some HARNs exhibit 4 – 7 cm difference with CORS
September 24, 2003 NGS Executive Steering Committee approved a plan for the readjustment of the horizontal positions and ellipsoid heights for GPS stations in the contiguous United States.
Orthometric Height adjustment will not be attempted
NSRS(2007) READJUSTMENT of NAD 83
ONLY GPS DATA WAS USED
CONTINUOUSLY OPERATING REFERENCE STATIONS FEDERAL BASE NETWORK (A & B)COOPERATIVE BASE NETWORK (B)
USER DENSIFICATION NETWORK (First)AIRPORT SURVEYS (B & First)
Errors
• All real observations contain errors– Two types of errors
• Random errors which mean to zero
• systematic errors which do not
• Least square will only give improved results if your errors are predominantly random
Random error
Systematic error
Example of redundancySuppose we are trying to determine the distance between two points
We have 5 measurementsall have equal precisionAny one measurement is enough to determine the distance but because every measurement contains measurement errors so each measurement gives a slightly different result
71 32 4 5 6 8 9 1110 12
502.100
401.100
300.100
299.99
198.99
try
try
try
try
try
Observation equations
• This means that each time we add an equation, we have one unknown residual to solve for plus the distance
• So we will never have enough equations to solve for the unknowns
300.100 vx
198.99 vx 299.99 vx
401.100 vx
502.100 vx
• For each observation we can write an equation relating the parameter we are trying to determine (the distance) to the observation and the residual.
Least Square condition
• Since we do not have 1 equation per unknown
• We have to add at least one more so we have enough information to determine all of the unknowns
• We add a condition that the sum of the squares of all of the residuals is a minimum
• This just means that the data is as close to the parameters (in this case the mean value) as possible
residuals theare
minimum2
v
v
Weighting• All least square adjustments include All least square adjustments include
some sort of estimate of the accuracy some sort of estimate of the accuracy of the measurementsof the measurements
• This allows measurements that are This allows measurements that are precise to have more importance (or precise to have more importance (or weight) than approximate weight) than approximate measurementsmeasurements
• The weighting for each observation is The weighting for each observation is equal to the inverse square of the equal to the inverse square of the standard deviationstandard deviation
• The idea is that if then error is small The idea is that if then error is small the weighting the weighting is largethe weighting the weighting is large
211
1
iiw
Minimally Constrained Adjustment
• Hold the minimum number of control points fixed to allow the least square process to work
– One fixed point for GPS
– 2 for triangulation survey without distance measurements
• The purpose of this adjustment is to
– Check the internal consistency of the network
– Detect blunders or ill-fitting observations
– Obtain accurate error estimates
How big do you make the bolt holes?
Residuals
• Residuals are the difference between the observed survey measurements and values calculated form coordinates from the least squares adjustment
– They follow a known statistical distribution
• and we can use statistics to identify observations with residuals are large enough to represent blunders that should be investigated further
1 2 3 41234
Critical Critical
Outliers Outliers
residualfor error Estimated
ResidualResidualStandard
Fully Constrained Adjustment• Hold all control points in the network fixed at values from
the NGS database
– Minimum of 2 for GPS surveys– 3 for triangulation survey without distance
measurements• The purpose of this adjustment is to
– Reference the network to existing control and develop final coordinates for the new control points that are being established
– Verify existing control. – If any control points are wrong
• the standard error of unit weight and residuals will increase compared to the minimally constrained adjustment
Helmert Blocks Each state will comprise a separate block of data.
Helmert Blocks
CORS/CGPS provided control at the top blockCGPS coordinates were determined by Scripps’ Sector utility projected to the 2007.0 epoch.
An attempt was made to create a separate block of data for each state to minimize the number of junction observations between blocks.
California, Florida, Minnesota, North and South Carolina were broken into multiple blocks because of the number of stations located in these blocks.
HB 1
HB 2
HB 3
HB 4
HB 5
HB8HB 9
HB16HB 17
FLGA AL MS
HB 18
NC SC
HB 19
HB 32
HB 33
HB10
HB11
HB 20
HB 21
HB 22
HB 23
HB 6
HB 7
HB 12
HB 13
HB 24
HB 25
HB 26
HB 27
HB 14
HB15
HB28
HB 29
HB 30
HB 31
HB 34
HB 35
HB 36
HB 37
HB 38
HB 39
HB 40
HB 41
HB 42
HB 43
HB 44
HB 45
HB 46
HB 47
HB 48
HB 49
HB 50
HB 51
OR WA CA AK PR VQ
VA WV MD PA DC DE NY NJ CT MA ME NH RI VT LA AR TN KY MO IL IN OH MI WI MN IA ND SD NE KS OK TX NM AZ CO UT NV ID MT WY
HELMERT BLOCKING STRATEGY
This is how each state fits into the National Readjustment
You are here
The National Readjustment General Comments
The CORS/CGPS sites were the control
Only GPS projects participated
The FBN/CBN Surveys are a key element since these are high accuracy (2 cm) surveys that tie the HARN to the CORS throughout the contiguous United States and provide more accurate values for the ellipsoid heights of most HPGN stations.
NEW STANDARDS FOR GEODETIC CONTROL
(http://fgdc.er.usgs.gov/standards/status/swgstat.html)
• local accuracy -------------- adjacent points• network accuracy ---------- relative to CORS
• Numeric quantities, units in cm (or mm)• Both are relative accuracy measures• Will not use distance dependent expression• Order/Class codes will no longer be used
SHIFTS (National results)
< 5 cm. in the horizontal component with an average shift of 2.2
cm.
< 10 cm. in the vertical component with an average shift of 4.6 cm.
ILLINOIS STATISTICS
• Total # of Stations: 2515• Max Horizontal Shift: 0.106
(m)• Average Hz Shift: 0.011 (m)• Max Vertical Shift: 0.173
(m)• Average Vt. Shift: 0.014 (m)
NAD 83 Adjustment 2007 - Ellipsoid Height
Time-line for National Readjustment Positions and Ellipsoid Heights
All projects loaded in the NGS database prior to November 15, 2005 were included in the National Readjustment
Projects submitted after 11/15/2005 were accepted and loaded into the database but were not included in the readjustment
Completed adjustment by February 10, 2007 deadline
New Datasheets including new positions and network accuracies available now.
Project Report (pending)
For Stations not Included
NGS recommends that NAD 83 data that is NOT part of the NSRS readjustment be readjusted by contractor/user with the original observations.
Because of the relatively small shifts anticipated, a
model such as NADCON will NOT be developed between previously determined GPS coordinates.
National Geodetic Survey, Retrieval Date = NOVEMBER 30, 2007 KG0640 *********************************************************************** KG0640 FBN - This is a Federal Base Network Control Station. KG0640 DESIGNATION - MEADES RANCH RESET KG0640 PID - KG0640 KG0640 STATE/COUNTY- KS/OSBORNE KG0640 USGS QUAD - MEADES RANCH (1978) KG0640 KG0640 *CURRENT SURVEY CONTROL KG0640 ___________________________________________________________________ KG0640* NAD 83(2007)- 39 13 26.71218(N) 098 32 31.74604(W) ADJUSTED KG0640* NAVD 88 - 600.3 (meters) 1969. (feet) GPS OBS KG0640 ___________________________________________________________________ KG0640 EPOCH DATE - 2002.00 KG0640 X - -734,972.580 (meters) COMP KG0640 Y - -4,893,188.504 (meters) COMP KG0640 Z - 4,011,982.822 (meters) COMP KG0640 LAPLACE CORR- -2.96 (seconds) DEFLEC99 KG0640 ELLIP HEIGHT- 573.979 (meters) (02/10/07) ADJUSTED KG0640 GEOID HEIGHT- -26.35 (meters) GEOID03
National Geodetic Survey, Retrieval Date = NOVEMBER 30, 2007 DI3428 *********************************************************************** DI3428 CORS - This is a GPS Continuously Operating Reference Station. DI3428 DESIGNATION - KSU1_KSUN_KS2006 CORS ARP DI3428 CORS_ID - KSU1 DI3428 PID - DI3428 DI3428 STATE/COUNTY- KS/RILEY DI3428 USGS QUAD - SWEDE CREEK (1982) DI3428 DI3428 *CURRENT SURVEY CONTROL DI3428 ___________________________________________________________________ DI3428* NAD 83(CORS)- 39 06 02.67730(N) 096 36 34.09342(W) ADJUSTED DI3428* NAVD 88 - DI3428 ___________________________________________________________________ DI3428 EPOCH DATE - 2002.00 DI3428 X - -570,503.804 (meters) COMP DI3428 Y - -4,923,592.374 (meters) COMP DI3428 Z - 4,001,208.587 (meters) COMP DI3428 ELLIP HEIGHT- 326.622 (meters) (01/??/07) ADJUSTED DI3428 GEOID HEIGHT- -29.93 (meters) GEOID03 DI3428 HORZ ORDER - SPECIAL (CORS) DI3428 ELLP ORDER - SPECIAL (CORS)
NAD 83 (2007) and NAD 83 (CORS)
NAD83 coordinates NAD83 coordinates 1997 adjustment1997 adjustment
Order of station Order of station in the old systemin the old system
Superseded coordinates Superseded coordinates do not include do not include NAD83(97)NAD83(97)
ME2940 DESIGNATION - TRYNER RESET ME2940 PID - ME2940 ME2940 STATE/COUNTY- IL/COOK ME2940 USGS QUAD - HARVEY (1993) ME2940 ME2940 *CURRENT SURVEY CONTROL ME2940 ___________________________________________________________________ ME2940* NAD 83(1997)- 41 35 09.16178(N) 087 43 48.51810(W) ADJUSTED ME2940* NAVD 88 - 209. (meters) 686. (feet) SCALED ME2940 ___________________________________________________________________ ME2940 LAPLACE CORR- -1.66 (seconds) DEFLEC99 ME2940 GEOID HEIGHT- -33.27 (meters) GEOID99 ME2940 HORZ ORDER - FIRST ME2940.The horizontal coordinates established by classical geodetic methods ME2940.and adjusted by the National Geodetic Survey in October 1999. ME2940; North East Units Scale Converg. ME2940;SPC IL E - 546,283.293 350,296.268 MT 1.00000612 +0 24 ME2940;UTM 16 - 4,604,055.820 439,140.542 MT 0.99964558 -0 29 ME2940 ME2940: Primary Azimuth Mark Grid Az ME2940:SPC IL E - TRYNER 1944 AZ MK 1959 046 20 05.8 ME2940:UTM 16 - TRYNER 1944 AZ MK 1959 047 13 11.8 ME2940 ME2940 ME2940 SUPERSEDED SURVEY CONTROL ME2940 ME2940 NAD 83(1986)- 41 35 09.16596(N) 087 43 48.52531(W) AD( ) 1 ME2940 NAD 27 - 41 35 09.04476(N) 087 43 48.35065(W) AD( ) 1 ME2940 ME2940.Superseded values are not recommended for survey control. ME2940.NGS no longer adjusts projects to the NAD 27 or NGVD 29 datums. ME2940 ME2940 STATION DESCRIPTION ME2940 ME2940'DESCRIBED BY COAST AND GEODETIC SURVEY 1956 (WNM) ME2940'THE STATION WAS FOUND IN GOOD CONDITION BUT FLUSH ME2940'WITH THE GROUND AS THE ME2940'RIGHT-OF-WAY HAS BEEN GRADED AT THIS LOCATION. OBSERVATIONS
Datasheets for excluded station
AC8865 DESIGNATION - MDW 11 AC8865 PID - AC8865 AC8865 STATE/COUNTY- IL/COOK AC8865 USGS QUAD - BERWYN (1993) AC8865 *CURRENT SURVEY CONTROL AC8865 ___________________________________________________________________ AC8865* NAD 83(2007)- 41 47 16.93979(N) 087 45 01.58973(W) ADJUSTED AC8865* NAVD 88 - 184.35 (meters) 604.8 (feet) GPS OBS AC8865 ___________________________________________________________________ AC8865 EPOCH DATE - 2002.00 AC8865 X - 186,951.240 (meters) COMP AC8865 Y - -4,759,161.802 (meters) COMP AC8865 Z - 4,228,179.637 (meters) COMP AC8865 LAPLACE CORR- -1.12 (seconds) DEFLEC99 AC8865 ELLIP HEIGHT- 150.966 (meters) (02/10/07) ADJUSTED AC8865 GEOID HEIGHT- -33.40 (meters) GEOID03 AC8865 AC8865 ------- Accuracy Estimates (at 95% Confidence Level in cm) -------- AC8865 Type PID Designation North East Ellip AC8865 NETWORK AC8865 MDW 11 0.63 0.49 1.74 AC8865.The horizontal coordinates were established by GPS observations AC8865.and adjusted by the National Geodetic Survey in February 2007. AC8865.The datum tag of NAD 83(2007) is equivalent to NAD 83(NSRS2007). AC8865.The horizontal coordinates are valid at the epoch date displayed above. AC8865.The orthometric height was determined by GPS observations and a AC8865.high-resolution geoid model. AC8865.The geoid height was determined by GEOID03. AC8865; North East Units Scale Factor Converg. AC8865;SPC IL E - 1,865,890.79 1,143,212.42 sFT 1.00000388 +0 23 18.4 AC8865! - Elev Factor x Scale Factor = Combined Factor AC8865!SPC IL E - 0.99997632 x 1.00000388 = 0.99998020 AC8865 SUPERSEDED SURVEY CONTROL AC8865 ELLIP H (09/22/04) 150.961 (m) GP( ) 4 1 AC8865 NAD 83(1997)- 41 47 16.93986(N) 087 45 01.58965(W) AD( ) B
NAD83 (NSRS2007) datasheet
Epoch dateEpoch date
Datum tagDatum tag
Ellip Ht GPSEllip Ht GPS
Ortho height Ortho height
accuracyaccuracy
ITRF00 to NAD 83 (CORS96)
New procedures for data submission for horizontal projects
• All projects will have to be adjusted using only NSRS2007 control points
• All projects will have to have at least one CORS tie• No error scaling is required now
– The program MODGEE.EXE will not be run• Changes soon may be required in the final free
adjustment– This may involve weighting the control using
accuracies form the datasheets
Geoid 06Earth’s Surface
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Ellipsoid
Composite Geoid
A new geoid GeoidA new geoid Geoid Warped to fit NRSR2007 ellipsoid Warped to fit NRSR2007 ellipsoid heights will be released soonheights will be released soon
The next height datumThe next height datum will be based on the gravity geoid will be based on the gravity geoid
Gravity GeoidGravity Geoid
0.27m in Joilet IL
IGA Crustal deformation for the midwest
