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Alabama Height Modernization Project, NAD 83(2011), and GEOID 12 in Alabama

Alabama Height Modernization Project, NAD 83(2011), and GEOID 12 in Alabama. Overview of Height Modernization Project NAD 83(2011) Adjustment GEOID 12. Alabama Height Modernization. Congressional Funding through NOAA – NGS Alabama Department of Revenue (ADOR) is grant recipient

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Alabama Height Modernization Project, NAD 83(2011), and GEOID 12 in Alabama

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  1. Alabama Height Modernization Project, NAD 83(2011), and GEOID 12 in Alabama Overview of Height Modernization Project NAD 83(2011) Adjustment GEOID 12

  2. Alabama Height Modernization • Congressional Funding through NOAA – NGS • Alabama Department of Revenue (ADOR) is grant recipient • Surveying Tasks Delegated to Alabama Department of Transportation (ALDOT) • Work began in 2005 and will be finished by the end of 2012

  3. Improving Heights obtained with GPS or Improving the GEOID Model 1 -Establish Network of marks with GPS to get good Ellipsoid Heights 2 – Establish good leveled heights on marks with good ellipsoid heights 3 – Utilize GPS benchmarks in development of new GEOID models

  4. Height Modernization Activities • GPS Surveys using procedures from NOS NGS 58 & 59 – 2 cm repeatable elevations from GPS. (1998 Report to Congress.) • First and Second Order Leveling to support NOS NGS 58 & 59 Surveys, improve the GEOID Model for Alabama, and to establish NAVD 88 heights at the CORS ARP. • CORS – Establish a state-wide CORS network to serve as the National Spatial Reference System (NSRS) for the state in the future and to provide data for monitoring crustal motion.

  5. HARN Observation • Planning began in October, 2003 • Joint Project with NGS, ASPLS, ALDOT • Observations scheduled for the week of June 21, 2004 • 125 total marks observed • 104 marks observed in Alabama

  6. 2003 2006

  7. Leveling Projects to support Primary and Secondary GPS Projects and establish NAVD 88 Heights on ARP of CORS Phase I – FBN Leveling • Second Order Class I Leveling • 545 miles w/ 324 new Benchmarks • Field work is complete and has been published by NGS. Phase II – CORS Leveling • Second Order Class I Leveling to Antenna Reference Plane (ARP) of CORS sites • Field work complete and approximately 75% of the data has been published. • Includes an additional 40 miles of First Order Class II leveling to verify Dauphin Island line. • Includes ties to tidal benchmarks at Dauphin Island and Mobile Docks • Phase II Leveling Total = 282 miles

  8. Improved GEOID • Primary Base Network of FBN Marks – Horizontal and vertical marks established on a 40 to 50 kilometer grid. • Leveling projects will ensure each FBN Station has a First or Second Order Elevation. These marks will be the foundation for the NOS NGS 58 & 59 surveys. • Additional leveling to CORS and other GPS marks along the route add more GPS Benchmarks for the model. • More elevations on good GPS Marks = better Geoid Model which results in improved GPS Elevations

  9. 2003 2012 GEOID03 = 181 Marks GEOID12 = 407 Marks

  10. 2003 2012 Additional GPS Benchmarks included in GEOID12

  11. Leveling Projects- FBN Leveling- Height Mod Survey- CORS- Tide Gauges- Ties to MDOT Leveling

  12. Project “A”Height Mod SurveyGPS Survey to establish 2 cm heightsNOS NGS 58 and 59 Survey for Local Base Stations

  13. Leveling to HARN Station 49-15Direct tie from existing First Order Line along US 45 to the new MDOT line along US 98

  14. Leveling to CORS site AL90Direct tie to MDOT levelingDirect tie to Tide Gauge at Mobile DocksEstablish elevation on NGS Tide Gauge Commemorative Mark

  15. Leveling to CORS site ALDISpur to Bayou La BatreSpur to Industrial ParkTie to Tide Gauge at Dauphin Island

  16. New minus Old Comparison along Dauphin Island Level line

  17. Leveling to CORS site ALFO in FoleyDirect tie to MDOT line

  18. CORS Leveling • In Louisiana, the system of benchmarks had been deemed “unreliable” • Transfer NAVD 88 orthometric heights to CORS ARP • Allow CORS network to serve as the vertical control for areas of subsidence

  19. Tide Gauges directly tied toDauphin Island CORS Dauphin Island CORS Tidal Benchmark NOAA Tide Gauge - Tide Gauges are tied to the Tidal Benchmarks. Each site has several marks in close proximity to the gauge. - Establish First or Second Order NAVD 88 Height at the Tidal Benchmark to provide an accurate tie to Tidal Datum. - Establish NAVD 88 Height at the CORS ARP

  20. CORS Velocities Estimated AL92 in Bay Minette - VZ = -0.0008 m/yr ALDI on Dauphin Island - VZ = -0.0008 m/yr ALFO in Foley - VZ = -0.0008 m/yr ALCT in Citronelle - VZ = -0.0008 m/yr AL84 in Grove Hill - VZ = -0.0008 m/yr ALEB in Brewton - VZ = -0.0008 m/yr Computed AL90 in Mobile - VZ = -0.0016 m/yr (comp) PCLA in Pensacola - VZ = -0.0015 m/yr (comp)

  21. Affects of CORS Adjustment in Southwest Alabama. Horizontal shifts seem to be consistent with the entire state (south and east) Vertical shifts vary No dramatic changes When do we change positions?

  22. CORS Positioning NGS no longer provides OPUS solutions using the NAD 83(96) epoch. As of July 15, all OPUS solutions are NAD 83(2011) ALDOT is currently using the NAD 83(96) epoch for RTK broadcasts and will update to NAD 83 (2011) soon. No dates have been set as of yet. Email sent out on July 3, 2012 seeking user input. Coordinate updates will be coordinated with Florida DOT, Tennessee DOT, and Mississippi.

  23. NAD 83 (2007) Adjustment of the Passive Network 2007 Adjustment did not seem to “fit” very well on static sessions. Group of marks that were excluded from the adjustment in Lawrence County – resolved. Group of marks in Jackson County with dramatic horizontal shifts – needs more review Suspected ellipsoid height problems in Southwest Alabama – needs more review NAD83 (2011) should be the best fit possible between the passive marks and CORS.

  24. Future of Height Modernization in Alabama All funding has been depleted and the possibility of additional funding is slim at best. We will continue processing all leveling data and complete all outstanding projects for submission to NGS. Initiating mark maintenance program for benchmark resets where marks are in danger of being disturbed. GEOID improvements – OPUS DB? GRAV-D?

  25. Draft Real Time Positioning Guidelines

  26. Questions, Comments? John D. Russell, PLS Alabama Department of Transportation Design Bureau – Location Section 334-242-6139 office • russellj@dot.state.al.us

  27. www.iheep2012.com

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