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US Army Corpsof EngineersPhiladelphia District
RTK-GPS for Dredging
Why Where How Much The Pay Back –
Time - Accuracy Production monitoring $$$$
US Army Corpsof EngineersPhiladelphia District
RTK-GPS for DredgingWHY
Improved Accuracy for both positioning & depth
Knowing the exact draft of the vessel enables increased accuracy for dredge cuts
Decrease possibilities of missing spot shoalsDredging around piers & pilings I am sure you know more reasons than me to
improve dredge position accuracy
US Army Corpsof EngineersPhiladelphia District
RTK - GPS Becomes
VRS – RTK - GPS
Virtual Reference System -
RTK – GPS !!!!
What next !!!!
US Army Corpsof EngineersPhiladelphia District
Virtual Reference Station RTK - GPS
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
US Army Corpsof EngineersPhiladelphia District
Virtual Reference Station RTK - GPS
What is this new term?
VIRTUAL - RTK- GPS
US Army Corpsof EngineersPhiladelphia District
Virtual Reference Station RTK - GPS
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.
US Army Corpsof EngineersPhiladelphia District
Would you like to:
Have your Dredge show up for a job and just start working
Not worry about tide stationsCut Accurate side slopesNot worry about cutting too shallow or too
deepAccurately monitor production
US Army Corpsof EngineersPhiladelphia District
VRS-GPSCan be integrated with
COE Silent Inspector Hypack – Dredge Pack Other custom -
production monitoring programs
US Army Corpsof EngineersPhiladelphia District
VRS – RTK - GPS
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
US Army Corpsof EngineersPhiladelphia District
RTK-GPS for DredgingWhere
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
US Army Corpsof EngineersPhiladelphia District
RTK-GPS for DredgingWhere
USAVarious State DOT DepartmentsCommercial groups Colleges & UniversitiesCOE - Philadelphia
US Army Corpsof EngineersPhiladelphia District
VRS - RTK-GPS for DredgingWhere
1. North Carolina Geodetic Survey2. South Carolina Geodetic Survey3. Minnesota DOT4. Ohio DOT5. Texas DOT6. Puget Reference Network (Washington State)7. Texas Cooperative Network8. University of Minnesota
US Army Corpsof EngineersPhiladelphia District
RTK-GPS for DredgingWhere
EuropeAustria, Belgium, Denmark, FinlandGermany, Norway, SwedenSwitzerland, United Kingdom
Japan
US Army Corpsof EngineersPhiladelphia District
RTK-GPS for DredgingHow Much?
Typical Dredge installationRTK-GPS receiver = $20,000Laptop / work station = $3,000Proxy-Cast Cellular Network Router = $1,000
Total - $24,000
US Army Corpsof EngineersPhiladelphia District
VRS-RTK-GPS Typical Components
Laptop Proxy Cast Cellular Data Collector
(optional)
RTK-GPS receiver
US Army Corpsof EngineersPhiladelphia District
VRS base position update
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
US Army Corpsof EngineersPhiladelphia District
Philadelphia DistrictVRS-GPS Network
US Army Corpsof EngineersPhiladelphia District
USACE VRS-GPS Network In Production
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
US Army Corpsof EngineersPhiladelphia District
VRS-GPS Rover Deployed in Remote Areas
US Army Corpsof EngineersPhiladelphia District
VRS-GPS Rover Deployed in Remote
Areas 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
US Army Corpsof EngineersPhiladelphia District
ATV - Used for Beach Surveys
US Army Corpsof EngineersPhiladelphia District
ATV – Used for Beach Surveys
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
US Army Corpsof EngineersPhiladelphia District
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
US Army Corpsof EngineersPhiladelphia District
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
US Army Corpsof EngineersPhiladelphia District
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
US Army Corpsof EngineersPhiladelphia District
RTK / NOAA PortsComparison
Single Baseline 0.1’ to 0.3’agreement VRS-GPS Constant 0.1’ agreement Testing Continues Full Documentation
Before Implementation
US Army Corpsof EngineersPhiladelphia District
Navigation Surveys & Dredging
Survey Vessel With VRS-GPS Installed
US Army Corpsof EngineersPhiladelphia District
US Army Corpsof EngineersPhiladelphia District
Monitoring Dredge Production Using VRS-GPS
COE Silent Inspector Hypack – Dredge Pack Other custom -
production monitoring programs
US Army Corpsof EngineersPhiladelphia District
Monitoring Dredge Production Using VRS-GPS
Current Dredge Monitoring TechniquesGPS using USCG Differential = 3 to 5 m Hz & No
vertical componentNav Sat = Horizontal ? & No Vertical componentPressure sensors for draft & load measurement +/-
0.5’ typicalRTK – GPS = 0.2’ Vertical
US Army Corpsof EngineersPhiladelphia District
One More ExampleProduction Monitoring
Typical Hopper Dredge Capacity100’ long x 20’ wide = 2,000 sq ft+/- 0.5’ pressure sensor = +/- 37 yards+/-0.2’ RTK-GPS = +/- 14 yards37 yards @ $25.00/ yard = +/- $925.0014 yards @ $25.00/ yard = +/- $350.00
It adds up in the long run
US Army Corpsof EngineersPhiladelphia District
Just some food for thought
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
US Army Corpsof EngineersPhiladelphia District
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