Ohio Height Modernization Related Activities

Great Lakes Regional ForumSept 24-25, 2008Madison, Wisconsin

David ConnerGeodetic Advisor to the State of Ohio

National Geodetic Survey, NOAA

Ohio Height ModernizationThe Early Years (or…What is Modern anyway?)

1983-2008 … Dozens of Bluebooked GPS projects throughout the State, all tied to NAVD88 benchmarks which now contribute to the Geoid model

1993 - L25429… a first order level line run the length of the State by NGS in cooperation with ODOT ... over 300 BM's including hundreds of new ones suitable for use by GPS. Many of these new NAVD88 BM's were subsequently included in GPS surveys and now contribute to the Geoid model.

Ohio Height ModernizationHigh Accuracy GPS

• 1995 - OH HARN established GPS BM’s at 50 km spacing recommended by NGS to support geoid modeling

• 1996 ODOT sponsors a study by NGS “An Accuracy Assessment of the Geoid96 Geoid Ht Model” to guide future planning

• 2003 - FBN/CBN re-obs included many BM’s using A-order specs to provide local vertical network ties to the CORS network

Ohio Height ModernizationGPS CORS

• 2001 – ODOT CORS Network a seventeen station network with 70 km average spacing selected in accordance with NOS NGS-58, a spacing that would allow these CORS to serve as Control for "Height Mod" surveys.

• 2003 - ODOT CORS Network expanded to ~53 stations with real-time positioning capability. Avg 40-45 km spacing would serve as "Primary Base" control in accordance with NOS NGS-58 … all are National CORS

Ohio’s GPS CORS Network

2003

Brought to you courtesy of ODOT Bureau of Aerial Engineering

VRS/ CORS information

Telephone: 614-275-1372, or

614-351-2839.

cors@dot.state.oh.us

Ohio Height Modernization

• 2005 – Great Lakes GPS Project – partnership between US and Canada… NOAA/NGS and eight Great Lakes States, including many people in the audience today

• 2006-2008 – ODOT Sponsored studies and pilot project, intended to build a case for HT Mod funding

• 2008 – Leveling to CORS ARP

Ohio Height Modernization

Ohio Height Modernization2008

ODOT begins leveling to establish precise ortho ht on CORS ARP

Vertical standard error achievable when a user submits 15 minutes of GPS data to OPUS-RS