1. Philadelphia District US Army Corps of Engineers

2. RTK-GPS for Dredging • Why • Where • How Much • The Pay Back – • Time - Accuracy • Production monitoring • $$$$

3. Improved Accuracy for both positioning & depth Knowing the exact draft of the vessel enables increased accuracy for dredge cuts Decrease possibilities of missing spot shoals Dredging around piers & pilings I am sure you know more reasons than me to improve dredge position accuracy RTK-GPS for DredgingWHY

4. Virtual Reference System - RTK – GPS !!!! What next !!!! RTK - GPS BecomesVRS – RTK - GPS

5. No more negotiating with local residents or businesses to put equipment up for the duration of a project No more dead batteries or power failures slowing or stopping work No more radio interference causing incorrect positions Virtual Reference Station RTK - GPS

6. What is this new term? VIRTUAL - RTK- GPS Virtual Reference Station RTK - GPS

7. Defined – A number of Continually Operating Reference Stations (CORS) connected by a network that computes real time (1/sec) GPS measurement corrections for an intermediate position used as a base station (virtual) when conducting RTK-GPS surveys. Virtual Reference Station RTK - GPS

8. Have your Dredge show up for a job and just start working Not worry about tide stations Cut Accurate side slopes Not worry about cutting too shallow or too deep Accurately monitor production Would you like to:

9. VRS-GPSCan be integrated with • COE Silent Inspector • Hypack – Dredge Pack • Other custom -production monitoring programs

10. Where did it come from? COE & DOT survey departments looking to improve efficiency and repeatability when performing surveys Being used in Europe by many industries Commercial groups are starting networks VRS – RTK - GPS

11. At this moment it is coming online in the Philadelphia District Once fully established in Philadelphia it is planned to expand through NAD We have received inquiries from various districts in SAD & MVD RTK-GPS for DredgingWhere

12. USA Various State DOT Departments Commercial groups Colleges & Universities COE - Philadelphia RTK-GPS for DredgingWhere

13. North Carolina Geodetic Survey South Carolina Geodetic Survey Minnesota DOT Ohio DOT Texas DOT Puget Reference Network (Washington State) Texas Cooperative Network University of Minnesota VRS - RTK-GPS for DredgingWhere

14. Europe Austria, Belgium, Denmark, Finland Germany, Norway, Sweden Switzerland, United Kingdom Japan RTK-GPS for DredgingWhere

15. Typical Dredge installation RTK-GPS receiver = $20,000 Laptop / work station = $3,000 Proxy-Cast Cellular Network Router = $1,000 Total - $24,000 RTK-GPS for DredgingHow Much?

16. VRS-RTK-GPS Typical Components • Laptop • Proxy Cast Cellular • Data Collector (optional) • RTK-GPS receiver

17. The default base station position remains fixed at the initial position determined during the first connection of the day Optionally the VRS base location can be set to update at specific intervals from the original location Good option for Hydrographic and Beach surveys VRS base position update

18. Philadelphia DistrictVRS-GPS Network

19. The Following Slides show some of the areas that the VRS-GPS Network is being used to improve Production New Projects and Applications are Being added to the List USACE VRS-GPS Network In Production

20. VRS-GPS Rover Deployed in Remote Areas

21. Quick survey team response Little or no stable control in the area Often calibration is performed several miles outside of the immediate project area Fast data acquisition Accuracies within project tolerances (0.1’v) Additional Rovers for data collection VRS-GPS Rover Deployed in Remote Areas

22. ATV - Used for Beach Surveys

23. Immediate Response to Pre and Post Storm Surveys – Destroyed Control is No Longer an Issue Regional Models are Now Surveyed with a Uniform Control Network – Island to Island Network Variations are Eliminated Contractors can be Given a User Name & Password that is Active while working on COE Projects ATV – Used for Beach Surveys

24. RTK / NOAA PortsComparison • Single Baseline Base • 185’ Light House • 85 Watt Radio • ~163 MHz VHF • 10 to 30 Km • 0.1 to 0.25 tide comparisons • Using Geoid 2003

25. RTK / NOAA PortsComparison • Delaware Bay • Brandywine Light • 10 KM from RTK Base • <0.1’ Difference • Repeated readings • Various tide / current conditions • Various GPS constellation conditions

26. RTK / NOAA PortsComparison • Delaware Bay • Ship John Light • 30 KM from RTK Base • +/-0.2’ Difference • Repeated readings • Various tide / current conditions • Various GPS constellation conditions

27. RTK / NOAA PortsComparison • Single Baseline • 0.1’ to 0.3’agreement • VRS-GPS • Constant 0.1’ agreement • Testing Continues • Full Documentation Before Implementation

28. Navigation Surveys & Dredging Survey Vessel With VRS-GPS Installed

30. Monitoring Dredge Production Using VRS-GPS • COE Silent Inspector • Hypack – Dredge Pack • Other custom -production monitoring programs

31. Current Dredge Monitoring Techniques GPS using USCG Differential = 3 to 5 m Hz & No vertical component Nav Sat = Horizontal ? & No Vertical component Pressure sensors for draft & load measurement +/- 0.5’ typical RTK – GPS = 0.2’ Vertical Monitoring Dredge Production Using VRS-GPS

32. Typical Hopper Dredge Capacity 100’ long x 20’ wide = 2,000 sq ft +/- 0.5’ pressure sensor = +/- 37 yards +/-0.2’ RTK-GPS = +/- 14 yards 37 yards @ $25.00/ yard = +/- $925.00 14 yards @ $25.00/ yard = +/- $350.00 It adds up in the long run One More ExampleProduction Monitoring

33. The survey industry is heading in this direction A uniform control network in the region Cellular connections Vs Radio Accuracy is constantly monitored by the network operator Accounts can be setup and billed as used or you can become a network partner Just some food for thought

34. Questions or Comments Some of the items discussed in this presentation are application ideas developed by the author and not presently in production or use by the COE