Height Modernization Making the Most of the Indiana HARN and the INDOT CORS March 14, 2007 By...

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Height ModernizationMaking the Most of the Indiana HARN and the INDOT CORS

March 14, 2007By

William A. Schmidt, PE, LSManager of Aerial Engineering,

INDOTThomas A. Mahon, PE, LS

Survey Group Manager, Woolpert Inc

Background – Surveying Infrastructure - Horizontal

• NAD 27 – Best fit Spheroid for North America

• Fifty nine years of terrestrial, local surveying by the general public

• Line of sight required (Bilby towers)• Regional or large scale projects only

conducted by National Geodetic Survey

• Highest achievable relative accuracy was 1:100,000

• Network accuracy 10 m

Background - Surveying Infrastucture (cont’d)Background - Surveying Infrastucture (cont’d)

Background – Surveying Infrastructure - HorizontalBackground – Surveying Infrastructure - Horizontal

•NAD 83(86) – Best fit Global Ellipsoid, conventional observations along with satellite triangulation, Doppler positions, and VLBI– Incorporated satellite (non-GPS)

observations into conventional data sets

– Largest solution of simultaneously adjusted equations up until that time

– 400,000 unknowns and 1,800,000 (observations) equations

Background – Surveying Infrastructure - HorizontalBackground – Surveying Infrastructure - Horizontal

•NAD 83(86) Issues– Not GPS-able– Poor accessibility– Irregularly spaced– Positional accuracy

•Relative 1:100,000•Network 1 m

Surveying Infrastructure – Horizontal (cont’d)Surveying Infrastructure – Horizontal (cont’d)

•Along came GPS•Private surveyors began finding

issues with existing control•Large scale surveys no longer the

domain of government surveyors•Projections and datums used•More ties to state plane coordinates•Both horizontal and vertical control in

one operation•Overall horizontal accuracy improving

Surveying Infrastructure in Indiana – HARNsSurveying Infrastructure in Indiana – HARNs

•“GPSABLE” Clear Horizons for Satellite Signal Acquisition

•EASY ACCESSIBILITY Few Special Vehicle or Property

Entrance Requirements

•REGULARLY SPACEDAlways within 20-100 Km

•HIGH HORIZONTAL ACCURACYA-Order (5 mm + 1:10,000,000)B-Order (8mm + 1:1,000,000)

Surveying Infrastructure in Indiana – HorizontalSurveying Infrastructure in Indiana – Horizontal

• Indiana HARN Phase I – 1997 (GPS1200)• Indiana HARN Phase II – 1998 (GPS1200)• Indiana HARN last of all 50 state HARN’s•No state HARN has better vertical

component•NAD 83(97) Statewide Readjustment by

NGS• ‘NAD 83’ no longer enough to define

adjustment• Indiana HARN Phase III - 2003 (GPS1850)

– FBN Vertical Enhancement Survey

High Accuracy Reference Network Positional AccuracyHigh Accuracy Reference Network Positional Accuracy

•HARN Stations– Network (absolute): 0.1 m– Relative

•B-order: one part per million• A-order: one part per 10 million

•CORS Stations– 0.01 m

Indiana HARN 1997/1998Indiana HARN 1997/1998

Phases of Indiana Surveying Infrastructure – Horizontal (cont’d)

•HARN Participants:– HARN Phase I - Collaborative effort

between federal government, local government, private contractors (The Schneider Corporation & Plumb-Tuckett) and various volunteers

– HARN Phase II - Private contractor (Woolpert LLP)

– HARN Phase III - federal government, local government and various volunteers. No private contractor.

Indiana HARN Components: FBN/CBNIndiana HARN Components: FBN/CBN

•The Indiana HARN consists of stations maintained by the federal government and those maintained by the locals (anyone other than the federal government)

•HARN – High Accuracy Reference Network (161 Total Points)

•FBN – Federal Base Network (21), a subset of HARN stations sufficiently dense for the federal government to meet their surveying obligations within the state (100 km)

•CBN – Cooperative Base Network (140), all other HARN stations, more densely spaced to meet local needs.

Indiana HARN w/ FBN StationsIndiana HARN w/ FBN Stations

GPS & CLASSICAL ADJUSTMENTS COMPLETEDGPS ADJUSTMENT COMPLETED

1990-GPS120

1991GPS222

1992GPS366

1997GPS11791992

GPS412

1992 GPS3831992

GPS450

1992GPS419

1992GPS394

1992GPS341

1993 GPS585

1993 GPS667

1992GPS376

1995GPS887

1991GPS197

GPS2601991

1995GPS908

GPS610

1993 GPS725

1994GPS404

GPS611

1994GPS633

1991 GP S291 reobs 9/97

1994 GPS721

reos 7/96 GPS1047

reos 1/96 GPS936

1997GPS1133

reos-6/95-GPS904

1995GPS852

1995GPS882

1993GPS606

1996GPS10481996

GPS8051996GPS941 1994

GPS7301996GPS1121

1997GPS1178

1997 GPS 12001997

GPS1150

reos-1996

Horizontal Control StationsHorizontal Control Stations

•A-order (13@1:10,000,000 horizontal)Adjusted to VLBI stations (NCMN 7291

Bloomington), CORS stations and other FBN stations

•B-order (148@1:1,000,000 horizontal)Adjusted to A-order stations

•C-order (all 1st, 2nd, and 3rd order stations)

Rubber sheeted to A & B-order stations

Indiana FBN Portion of the Indiana HARNIndiana FBN Portion of the Indiana HARN

Horizontal AdjustmentsHorizontal Adjustments

•NAD 83(97)– adjusted horizontal coordinates in

Indiana based on the first two HARN campaigns

– adjustment based on NAD 83(CORS) which had been adjusted in 1996

– adjustment tied into surrounding readjustment

– adjusted coordinates moved on the order of magnitude of ±1’ in Indiana

– adjusted only satellite observations and rubber sheeted conventional control into HARN stations

Horizontal AdjustmentsHorizontal Adjustments

•NAD 83(NSRS2007)– NSRS - National Spatial Reference System– readjustment of all GPS data in the

National Spatial Reference System simultaneously, not just a state or regional readjustment

– adjustment tied to CORS network as of 2002

– adjusted data in Indiana to be available Spring 2007

– states on stable North American plates will not be given an epoch date (considered fixed)

NAD 83(NSRS2007)NAD 83(NSRS2007)

Phases of Surveying Infrastructure – VerticalPhases of Surveying Infrastructure – Vertical

•NGVD 29 – National Geodetic Vertical Datum of 1929 (sea level)

•Thousands and thousands of km of level loops run since 1929

•NAVD 88 – North American Vertical Datum of 1988

•Many monuments have move or been destroyed over the years

Phases of Indiana Surveying Infrastructure – Orthophotography & DEM

•Statewide Digital Color Orthophotography – 2005

•Statewide Color Infrared Aerial Photos – 2005

•Statewide Digital Elevation Model – 2005

•Statewide Digital Surface Model – 2005

•gis.iu.edu•Google Earth

What’s Next – Height ModernizationWhat’s Next – Height Modernization

•Height Modernization is any program aimed at improving elevation estimates

•Typical activities have included:– differential leveling establishing/re-

establishing elevations on horizontal control stations

– survey mark recovery and remonumentation

– GPS surveying establishing horizontal positions and ellipsoidal heights on bench marks

– Gravity data observations for inclusion in the national geoid model

Height Modernization in IndianaHeight Modernization in Indiana

•Supplements the HARN and INDOT CORs

•To be done in phases•Phase I – differential leveling

– By INDOT District starting in Vincennes District

•Phase II – GPS observations on additional bench marks

Height Modernization in Indiana – Phase I (Vincennes)

Height Modernization in Indiana – Phase IHeight Modernization in Indiana – Phase I

125 miles of leveling in Vincennes District

•$1,500/mile•$190,000 for Vincennes District•Extrapolating to entire state

$1,140,000

•Funding for OISGA– $60,000

•Total for Phase I - $1.2M

Height Modernization in Indiana – Phase I ActivitiesHeight Modernization in Indiana – Phase I Activities

•Virtual Mark Recovery•Actual Mark Recovery•Coordination with INDOT CORS•Planning and Route Selection•Differential Leveling•Adjustment and Report

Height Modernization in IndianaHeight Modernization in Indiana

•Questions?

Height Modernization Making the Most of the Indiana HARN and the INDOT CORS March 14, 2007 By...

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