US Army Corps of Engineers Philadelphia District RTK-GPS for Dredging Why Where How Much The Pay Back – Time - Accuracy Production monitoring $$$$

US Army Corpsof EngineersPhiladelphia District

RTK-GPS for Dredging

Why Where How Much The Pay Back –

Time - Accuracy Production monitoring $$$$


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


RTK - GPS Becomes

VRS – RTK - GPS

Virtual Reference System -

RTK – GPS !!!!

What next !!!!


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



What is this new term?

VIRTUAL - 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.


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


VRS-GPSCan be integrated with

COE Silent Inspector Hypack – Dredge Pack Other custom -

production monitoring programs


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


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



USAVarious State DOT DepartmentsCommercial groups Colleges & UniversitiesCOE - Philadelphia


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



EuropeAustria, Belgium, Denmark, FinlandGermany, Norway, SwedenSwitzerland, United Kingdom

Japan


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


VRS-RTK-GPS Typical Components

Laptop Proxy Cast Cellular Data Collector

(optional)

RTK-GPS receiver


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


Philadelphia DistrictVRS-GPS Network


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


VRS-GPS Rover Deployed in Remote Areas


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


ATV - Used for Beach Surveys


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


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



Delaware Bay Brandywine Light 10 KM from RTK Base <0.1’ Difference Repeated readings Various tide / current

conditions Various GPS

constellation conditions



Delaware Bay Ship John Light 30 KM from RTK Base +/-0.2’ Difference Repeated readings Various tide / current

conditions Various GPS

constellation conditions



Single Baseline 0.1’ to 0.3’agreement VRS-GPS Constant 0.1’ agreement Testing Continues Full Documentation

Before Implementation


Navigation Surveys & Dredging

Survey Vessel With VRS-GPS Installed



Monitoring Dredge Production Using VRS-GPS

COE Silent Inspector Hypack – Dredge Pack Other custom -

production monitoring programs


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


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


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


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

US Army Corps of Engineers Philadelphia District RTK-GPS for Dredging Why Where How Much The Pay Back – Time - Accuracy Production monitoring $$$$

Documents

gps slide

rtkgps surveys

production slide

virtual rtk

list slide

dredge position accuracy

data collection slide

university of minnesota