National Readjustment

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National Readjustment

• Kathy Milbert

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The National ReadjustmentGeneral Comments

• The CORS will provide the control
• Only GPS projects will participate
• 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
• An adjustment analysis of each GPS project that
  contributes to the National Spatial Reference
  System is required prior to the National
  Readjustment

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The National ReadjustmentMore Comments

• Statewide GPS Readjustments provide extra
  information about the network on a state by state
  basis
• A readjustment plan that properly classifies all
  GPS projects comprising the network is required

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FBN/CBN Surveys

• Status
• Observations complete for 48 contiguous states
  and the District of Columbia
• Reductions Adjustment complete for 43 States
  and the District of Columbia
• IN, OH, KY, TN, MO to go
• VA needs to be re-processed (Leica SR399
  Antennas)

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Project Adjustment Analysis

• 3065 Projects complete
• Free Adjustment
• Residual Plot
• Outliers Rejected
• Connectivity to A/B Order Network Verified
• Summary sheet with Project Information Created
• 59,395 stations

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A lot of projects
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Statewide GPS Readjustments

• Complete for 36 of 43 States and DC
• Readjustment of EHs and/or Positions (5cm
  tolerance)
• Layered Adjustment Approach Used
• States not Completed
• MN GA-Met 5 cm tolerance set by ESC
• CA-Requires special analysis
• SD, IL, KS IA-Recently loaded

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Centralization of Project Information

• Master File Created
• Information from Individual Projects
• Information from State GPS Readjustment

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Example

• OBS_SOURCE A B 1
• ------------- --- --- --- ND HARN-B
  Order-1996- Excellent residuals-3 cm or
  less
• GPS1048/B 2 6 0 MN No GPS readjustment
  performed in this state
• GPS1048/B 2 6 0 SD
• GPS1048/B 5 39 0 ND Level 2 of 3 in ND
  GPS readjustment
• GPS1048/B 6 2 0 MT All either in FBN
  or in ID/MT HARN-Not included in ID/MT
  GPS Readjustment

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Concept of Operation

• Adjust software will be used
• Layered Approach (except possibly CA)
• National Layers (Higher Order Projects)
• Regional Layers (UDN/First Order or Lower)
• Coordinates Produced and Published for both NAD83
  (NSRS) and ITRF
• Adjustment in NAD83-Transformed to ITRF
• Canadian Data Integrated at FBN/CBN Layer
• Network and Local Accuracies also Produced

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Local and Network Accuracies

• Local Accuracy of a control point
• A value that represents the uncertainty of its
  coordinates relative to other directly connected,
  adjacent control points at the 95-percent
  confidence level
• An approximate average of the individual local
  accuracy values between this control point and
  other observed control points used to establish
  its coordinates

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Local and Network Accuracies

• Network accuracy of a control point
• A value that represents the uncertainty of its
  coordinates with respect to the geodetic datum at
  the 95-percent confidence level
• Datum is considered to be best expressed by the
  Continuous Operating Reference Stations (CORS)
• Local and Network accuracy values at CORS sites
  are considered to be infinitesimal (approach
  zero)
• These accuracies will be implemented with the
  National Readjustment

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National Layers

• N0-The National CORS coordinate set
• N1-The FBN/CBN projects (3209 stations)
• N2-A B Order projects with CORS ties (2203
  stations)
• FAACORS-FAA projects with CORS ties (2288
  stations)
• N3-A Order projects without CORS ties (292
  stations)
• N4-B Order projects without CORS ties (6169
  stations)
• N5-Combination B 1st Order projects without
  CORS ties
• and 1st Order Projects with CORS ties (3721
  stations)
• AIR-Lower Order FAA Projects without CORS ties
  (7593 stations)

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Regional Layers

• UDN Projects (First and Lower)
• 7 Geographic Regions
• 3 Categories
• R1-Recent (Post 1992)-Residuals Under 7 cm
• R2-Residuals Under 15 cm
• R3-Either Large Residuals or Weak Geometry but
• with some redeeming value to the
  community

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Region 1

• Florida Alabama and Georgia
• Proj R1 Sta R1 Proj R2 Sta R2 Proj R3
  Sta R3
• FL 63 2693 13 1280 14
  1002
• AL 0 0 34 3584 0
  0
• GA 9 644 3 201 2
  227
• 72 3337 50 5065 16
  1229

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Region 2

• North Carolina and South Carolina
• Proj R1 Sta R1 Proj R2 Sta R2 Proj R3 Sta R3
  
• SC 44 1826 13 1142 8 575
• NC 75 3315 11 568 6 154
• 119 5141 24 1710 14 729

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Region 3

• VA, MD, DC, DE, WV, NJ, PA, NY, CT, MA, RI, NH,
  VT ME
• Proj R1 Sta R1 Proj R2 Sta R2 Proj
  R3 Sta R3
• VA 14 966 3 65 10
  547
• MD 27 1406 5 304
  5 32
• DC 1 11 1 11 0
  0
• DE 1 8 0 0 0
  0
• WV 1 20 0 0 1 7
• NJ 33 1199 2 21 0
  0
• PA 12 267 0 0 2
  87
• NY 4 637 2 31 0
  0
• CT 0 0 0 0 0 0
• MA 2 31 0 0 0 0
• RI 3 87 0 0 0
  0
• NH 0 0 0 0 0 0
• VT 10 613 0 0 0 0
• ME 3 40 0 0
  0 0
• 111 5285 13 432 18
  673

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Region 4

• MS, LA, AR, TN, KY, MO, IL, IN, OH, MI, WI IA
• Proj R1 Sta R1 Proj R2 Sta R2
  Proj R3 Sta R3
• MS 2 34 1 16
  0 0
• LA 6 170 2 453
  9 304
• AR 1 88 0 0
  1 260
• TN 0 0 3 227
  0 0
• KY 3 406 4 129
  0 0
• MO 4 504 5 106
  1 143
• IL 22 998 3 291
  1 344
• IN 0 0 2 14
  0 0
• OH 25 1653 10 760
  5 248
• MI 13 421 12 276
  1 88
• WI 6 540 2 118
  0 0
• IA 1 16 0 0
  0 0
• 83 4830 44 2390
  18 1387

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Region 5

• TX, OK, KS, NE, SD, ND MN
• Proj R1 Sta R1 Proj R2 Sta R2 Proj
  R3 Sta R3
• TX 3 166 2 175
  2 35
• OK 0 0 0 0
  1 23
• KS 0 0 1 73
  0 0
• NE 0 0 0 0
  0 0
• SD 1 28 0 0
  1 11
• ND 2 26 0 0
  1 45
• MN 81 3636 1 16
  3 143
• 86 3856 4 264
  8 257

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Region 6

• NM, AZ, CO, UT, NV, WY, MT, ID, OR WA
• Proj R1 Sta R1 Proj R2 Sta R2
  Proj R3 Sta R3
• NM 3 185 0 0
  0 0
• AZ 1 25 5 227
  1 30
• CO 60 1155 7 198
  6 139
• UT 0 0 0 0
  3 36
• NV 0 0 0 0
  0 0
• WY 0 0 0 0
  1 6
• MT 8 46 5 29
  1 5
• ID 4 25 3 42
  1 22
• OR 3 19 0 0
  3 74
• WA 8 530 1 46
  5 150
• 87 1985 21 542
  21 462

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Region 7

• California
• Requires separate analysis
• Projects not yet included in Master Plan Yet
• Breakdown
• Number of Projects Number of Stations
• N2 24 355
• FAACORS 25 84
• N3 1 9
• N4 14 258
• N5 23 335
• AIR 49 273
• UDN 70 1529

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TRASH

• Projects Not Recommended for Inclusion
• 149 Projects with 9903 stations
• Many Third Order FAA Projects from 1980s
• Some Projects that have no ties to the Network
• Includes Original TN HARN (Macrometer Data)
• Included Original Eastern Strain Network Project

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Ongoing Tasks

• Project Level Analysis (Free Adjustments)
• State GPS Readjustments (as required)
• Master Plan Updates-Layer Assignments
• Airport Layer Verification

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New Tasks

• California Data Analysis
• Identify and Resolve Project Weighting Scheme
  Deficiencies
• Facilitate the Implementation of Local and
  Network Accuracies in the National Readjustment

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Time-line for National Readjustment

• Proposed starting date June 2005-Some unexpected
  but reasonable delays have been factored in
• Time-lines for new tasks are flexible but
• MUST BE COMPLETED BY JUNE 2005
• OR
• NATIONAL READJUSTMENT ALSO DELAYED

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Contingency Option

• In case of large delays in New Tasks/Software
• Perform Statewide GPS Readjustments of both
  horizontal positions and ellipsoid heights
• Approved by Executive Steering Committee on
  September 24, 2003

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Time-line for National Readjustment Positions
and Ellipsoid Heights

• All new tasks completed by 06/2005
• National Layers
• N1-06/2005-12/2005
• N2 FAACORS-01/2006-02/2006
• N3-03/2006
• N4-04/2006-05/2006
• N5-06/2006-07/2006
• AIR-08/2006-10/2006

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Time-line for National Readjustment
Positions/Ellipsoid Heights (continued)

• Regional Layers
• Layers 1-7 (6 weeks for each region)
• November 2006 through September 2007
• Project Report
• 3 Months-October 2007 through December 2007
• Could be sped up by using more personnel-Up to 3
  regions could be worked on simultaneously

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Time-line for Project Submissions

• Higher Order Projects
• Stop 2 months prior to the completion of N1
• Proposed November 1, 2005
• Resume after all national layers are complete
• Proposed November 1, 2006
• Lower Order Projects (UDN)
• Stop 6 weeks prior to the start of a region
• Resume after a region is complete

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Post National Readjustment

• A transformation model for classical non-GPS
  stations and GPS stations that were excluded from
  the National Readjustment will be needed
• New adjustment procedures need to be developed
  that incorporate local and network accuracies
• Areas outside the contiguous US may need to be
  readjusted (ie Alaska Hawaii)
• A reference frame maintenance strategy (NAD83,
  ITRF, either or both) needs to be developed

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THATS ALL FOLKS !!!