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Welcome to the Alaska Height Modernization Forum 5 October 2005

Welcome to the Alaska Height Modernization Forum 5 October 2005. Alaska Height Issues. The state does not have adequate vertical coverage Legally established vertical datum is the North American Vertical Datum of 1988 In Alaska, we have a few NAVD88 points Most are NGVD29

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Welcome to the Alaska Height Modernization Forum 5 October 2005

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  1. Welcome to the Alaska Height Modernization Forum 5 October 2005

  2. Alaska Height Issues • The state does not have adequate vertical coverage • Legally established vertical datum is the North American Vertical Datum of 1988 • In Alaska, we have a few NAVD88 points • Most are NGVD29 • Coastal datum is Local Tidal Datum

  3. What’s the Problem? • Having a conglomeration of disparate datums means commonality is not inherent • Vertically, Alaska has challenges • Local Tidal Datums • Mean Sea Level, aka NGVD29 • NAVD88 • Ellipsoid heights not reduced to ground

  4. Alaska’s Current Horizontal Net • In the NGS Database - 24028 • 10043 have been visited and are still viable • 13905 are missing or have never been recovered since their installation • 58% of the current horizontal network is suspect

  5. Alaska’s Current Vertical Net • In the NGS database - 3381 • 1660 have been visited and are still viable • 1721 are missing or have never been recovered since their installation • 50% of the current vertical control network is suspect

  6. Bench Marks per Mile • 18,168 miles of road and rail in the state • State Highways • Railroad • 3381 markers for 18,168 miles ≈ 5 ½ miles per marker • How do we tie vertically anything off the road network?

  7. Horizontal • Programs to improve the latitude and longitude coordinates to the NAD83 • HARN • CORS • PBO • HEIGHT MODERNIZATION

  8. HARN

  9. Continuously Operating Reference Stations

  10. Plate Boundary Observatory

  11. What we should consider • Become aware of the issues of the Alaska control network • What the NGS Ht Modernization program is • Options for improvement • How much this could cost – • Finances • Manpower • Time

  12. What we can have with Ht Mod • Improved disaster preparedness • Improved tectonic modeling • Improved surveying techniques • Better resource management through GIS analysis • More confidence in navigational surveys (better charting) • More confidence in airport surveys • Better coastal erosion analysis • Money-saving efforts to improve our position in the horizontal and vertical world

  13. Today’s Agenda

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