If NAD27 Alaska will not go away what can I do

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If NAD27 Alaska will not go away what can I do?
James E. Mitchell, PLS The Crazy Mountains Joint
Venture
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NAD27 Alaska

• NAD27
• GPS

Courtesy NOAA Photo Library
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Asset Inventory AWWU

• Pilot Study
• Legacy NAD27 Database
• GPS to recover buried assets
• Accuracy
• DGPS
• RTK GPS

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Asset Inventory AWWU

• NAD27 Problems
• Database Accuracy
• Transformation of the GPS Data

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Asset Inventory AWWU

• Solution
• RTK GPS NAD83 CORS
• Attribute NAD83 coordinate to NAD27 database
• Custom Navigation Software
• Winter Trials RTK preferred over DGPS

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Cadastral Surveys

• PLSS
• Protraction Diagrams NAD27
• System designed to handle errors

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Cadastral Surveys

• Dependent Resurvey
• Unalaska Island
• Protraction
• Ear Mountain
• Hybrid
• North Slope

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Unalaska Island

• 1985 - Doppler Control Survey
• 1986 - Rectangular Survey ISS
• 2004 - Dependent Resurvey

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Ear Mountain
THIS SURVEY T6N R36W KRM
UNSURVEYED STATE SELECTION 70 TWPs.
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Ear Mountain

• Single Point Translation
• NADCON
• Network
• Translate Protraction to NAD83
• USE GPS measurements North 80 chains

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Ear Mountain
18 New Corners
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RM1
1949 Description Projects 4 inches
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Transformation

• EAR MTN NGS Data
• NAD 83(1986) 65 55 16.58177(N) 166 14
  43.38774(W)
• NAD 27 65 55 19.23300(N) 166 14
  33.48000(W)
• NAD83 - NAD27 N 57 E 490

• SE Corner of Township (BLM Protraction)
• NAD 27 65 52 15.12500(N) 166 08
  21.66399(W)
• NAD 83(1986) 65 52 12.47377(N) 166 08
  31.57173(W) After Translation

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Ear Mountain Future Work

• NAD27 DatumS
• Systematic Errors
• Blunders

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Ear Mountain Future Work

• Control Points
• NUGGET 12km East ? West 0.2
• TUTTLE 16km West ? North 0.5 m

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North Slope
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North Slope

• 111 Townships / 640 NEW corners
• West Bdy. Previously Surveyed

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North Slope

• 61 Existing Survey Corners
• 35 NGS Control Points

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North Slope

• What to Do?
• Control Survey
• Derive and Apply Translation
• Assign New NAD27 coordinate

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Conclusions

• Plat Show NAD83 CORS
• BLM GCDB
• NAD83 OBSERVATIONS