Height Modernization Making the Most of the Indiana HARN and the INDOT CORS March 14, 2007 By William A. Schmidt, PE, LS Manager of Aerial Engineering, INDOT Thomas 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 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 - 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) 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 – HARNs “GPSABLE” Clear Horizons for Satellite Signal Acquisition EASY ACCESSIBILITY Few Special Vehicle or Property Entrance Requirements REGULARLY SPACED Always within Km HIGH HORIZONTAL ACCURACY A-Order (5 mm + 1:10,000,000) B-Order (8mm + 1:1,000,000)

Surveying 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 (GPS1850) –FBN Vertical Enhancement Survey

High 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 1997/1998

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/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 Stations

GPS & CLASSICAL ADJUSTMENTS COMPLETED GPS ADJUSTMENT COMPLETED GPS GPS GPS GPS GPS GPS GPS GPS GPS GPS GPS GPS GPS GPS GPS GPS197 GPS GPS908 GPS GPS GPS404 GPS GPS GP S291 reobs 9/ GPS721 reos 7/96 GPS1047 reos 1/96 GPS GPS1133 reos-6/95-GPS GPS GPS GPS GPS GPS GPS GPS GPS GPS GPS GPS1150 reos-1996

Horizontal Control Stations A-order horizontal) Adjusted to VLBI stations (NCMN 7291 Bloomington), CORS stations and other FBN stations B-order horizontal) Adjusted to A-order stations C-order (all 1 st, 2 nd, and 3 rd order stations) Rubber sheeted to A & B-order stations

Indiana FBN Portion of the Indiana HARN

Horizontal 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 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)

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

Height Modernization in Indiana Questions?