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

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

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

Height Modernization Activities GPS Surveys using procedures from NOS NGS 58 & 59 – 2 cm repeatable elevations from GPS. (1998 Report to Congress.) 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. 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. 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.

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

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 Second Order Class I Leveling 545 miles w/ 324 new Benchmarks 545 miles w/ 324 new Benchmarks Field work is complete and has been published by NGS. 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 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. 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 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 Includes ties to tidal benchmarks at Dauphin Island and Mobile Docks Phase II Leveling Total = 282 miles Phase II Leveling Total = 282 miles

Improved GEOID Primary Base Network of FBN Marks – Horizontal and vertical marks established on a 40 to 50 kilometer grid. 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. 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. 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 More elevations on good GPS Marks = better Geoid Model which results in improved GPS Elevations

GEOID03 = 181 MarksGEOID12 = 407 Marks GEOID03 = 181 MarksGEOID12 = 407 Marks

Additional GPS Benchmarks included in GEOID12 Additional GPS Benchmarks included in GEOID12

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

Project “A” Height Mod Survey GPS Survey to establish 2 cm heights NOS NGS 58 and 59 Survey for Local Base Stations

Leveling to HARN Station Direct tie from existing First Order Line along US 45 to the new MDOT line along US 98

Leveling to CORS site AL90 Direct tie to MDOT leveling Direct tie to Tide Gauge at Mobile Docks Establish elevation on NGS Tide Gauge Commemorative Mark

Leveling to CORS site ALDI Spur to Bayou La Batre Spur to Industrial Park Tie to Tide Gauge at Dauphin Island

New minus Old Comparison along Dauphin Island Level line

Leveling to CORS site ALFO in Foley Direct tie to MDOT line

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

Tide Gauges directly tied to Dauphin Island CORS Tidal Benchmark - 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 NOAA Tide Gauge Dauphin Island CORS

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

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

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) 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. 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. sent out on July 3, 2012 seeking user input. sent out on July 3, 2012 seeking user input. Coordinate updates will be coordinated with Florida DOT, Tennessee DOT, and Mississippi. Coordinate updates will be coordinated with Florida DOT, Tennessee DOT, and Mississippi.

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

Future of Height Modernization in Alabama All funding has been depleted and the possibility of additional funding is slim at best. 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. 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. Initiating mark maintenance program for benchmark resets where marks are in danger of being disturbed. GEOID improvements – OPUS DB? GRAV-D? GEOID improvements – OPUS DB? GRAV-D?

Draft Real Time Positioning Guidelines

Questions, Comments? John D. Russell, PLS Alabama Department of Transportation Design Bureau – Location Section office