NM Height Modernization Digital Leveling Workshop

1. NM Height Modernization Digital Leveling Workshop CNM Montoya Campus - Albuquerque, NM May 12, 13, & 14, 2009 Digital Leveling with the Wild NA3000 Earl F. Burkholder, PS, PE NMSU Surveying Engineering Program

2. NM Height Modernization Digital Leveling Workshop • Goals for Height Modernization are to: 1. Economically establish reliable elevations to federal standards using new technology. 2. Build capacity for geodetic (surveying) leveling in the professional community. • Technology for Ht Modernization includes: 1. GPS and geoid modeling. 2. Digital leveling.

3. NM Height Modernization Digital Leveling Workshop • Evolution 1st order leveling, analog to digital. • Analog: 1. Precise level with parallel plate micrometer – range of 1.0 cm. 2. Calibrated invar scale rods – 2 scales. 3. Optical reading, manual recording. • Digital: 1. Precise level with built-in sensor/computer. 2. Calibrated invar bar-scale rods. 3. Electronically read and recorded.

4. NM Height Modernization Digital Leveling Workshop • This workshop looks at digital leveling. • GPS leveling - El Paso June 2007 • Digital leveling - NMSU Sept 2007 • Digital leveling + blue-booking – now • Supported by NM/TX Height Modernization grant for 2008-2009. 1. Two CORS – NMSU & elsewhere. 2. Outreach – Workshop for users.

5. NM Height Modernization Digital Leveling Workshop • This example is an actual project. • Klamath Falls - active geothermal area. • Settlement of school building. • Differential settlement eventually destroyed part of building. • Monitoring movement since 1986. • New wing built in 1990’s.

6. NM Height Modernization Digital Leveling Workshop • Monitor 150 points in and around building located in subsidence area. • Relative to stable on-site benchmark. • Repeated 3-4 times per year for 8 years. • First-order invar scale rods • Traditional, then digital in 1994. • Transition analog to digital.

9. NM Height Modernization Digital Leveling Workshop • Pentax L10 First-order level with built-in parallel plate micrometer – 0.1 mm. • Dual graduations invar scale rods. • C-factor determination each campaign. • Umbrella for outside set-ups. • Not possible to balance BS & FS • Corrections applied to each shot.

11. NM Height Modernization Digital Leveling WorkshopSite Diagram

12. NM Height Modernization Digital Leveling WorkshopBench Mark Next to Site

13. NM Height Modernization Digital Leveling Workshop • Approx. 150 points – inside/outside. • Numerous loops on several levels. • TP’s: studs in walls, rivets in floors. • Hand recording. • Spreadsheet manipulation. • Least squares adjustment – Star*Net.

14. NM Height Modernization Digital Leveling Workshop • Star*Net Adjustment (see output). • Very small residuals – biggest is 0.5 mm. • Find blunder if loop miscloses by 1.0 mm. • Most points part of loop. • Some points were side-shots: 1. Review from epoch to epoch. 2. Test those that look suspicious. 3. Or rare occasion – go back & reobserve.

15. NM Height Modernization Digital Leveling Workhop • Digital level first used in 1994. • Parallel operation first time: 1. Manually record readings and 2. Store electronically. • Download file to spreadsheet. • Parse and manipulate to apply corr’ns. • Least squares adjustment – excellent results.

16. NM Height Modernization Digital Leveling WorkshopRaw Data from Digital Level

17. NM Height Modernization Digital Leveling WorkshopStar*Net Input of Elevation Differences

18. NM Height Modernization Digital Leveling WorkshopResiduals elevation differences – 0.5 mm is largest

19. NM Height Modernization Digital Leveling WorkshopResiduals of elevation differences – 0.5 mm largest

20. NM Height Modernization Digital Leveling WorkshopResults as reported to client – recent/total movement

21. NM Height Modernization Digital Leveling Workshop • End • Thank you for your interest in Height Modernization in New Mexico. • Earl F. Burkholder, PS, PE NM Height Modernization PI