Using GNSS Technology to Accurately Bring Field Information Into GISDaniel J. Yaw Jr.

About the Presenter

Responsible for the upkeep and coordination of GIS and GNSS initiatives 550+ miles of active water main80+ square mile of service area33,000+ services3,500+ fire hydrants12,000+ valvesLinkedIn.com/in/DanielYawJr

Engineering and GIS Technician at North Penn Water Authority

• Medium size municipal public water system• Located about 45 min. NE of Philadelphia, PA

8+ years experience working with GISBachelors in Management, Certificates in Construction

Management and Drafting & Design

Daniel J. Yaw Jr.

The Problem / Old GIS Update Process

• Field changes need to be brought into GIS• Prior to 2014, we used only tabular field notes and sketches

• New roadways exported from CAD to GIS- Used to draw in assets

The Problem / Old GIS Update Process

• Hard to read• Referenced measurements off locations (including

roads) not on aerials• Compounding errors• Often missing measurements, wrong, or hard to read• Roadways brought in from CAD never aligned

correctly

The Solution

• High accuracy MGIS grade GPS/GNSS technology

• Trimble GeoXH 6000 and Geo7X with Zephyr Model 2 w/ external antenna and VRS

• Tested on ten projects to confirm the process • Used on every project since

What’s GNSS?

• Global Navigation Satellite System• All satellite positioning systems are a GNSS system• Top two GNSS systems:

- GPS (Global Positioning System): US owned GNSS- GLONASS (Global Navigational Satellite System): Russian owned

GNSS

• How’s GPS work?- Triangulation of position- Uses the time it takes for the radio signal to reach the receiver- Accounts for errors - The clocks need to be very accurate

What’s VRS?• Virtual Reference Station• Accuracy level: total errors

- Distance Errors- Multipath Errors

• Uses multiple reference stations• Error computed on a computation server • Computation server creates a VRS near your initial position

• Very high real time accuracy• http://goo.gl/VxMPD

Equipment

• Trimble Zephyr Model 2 Antenna- High accuracy- GPS , GLONASS

• 4G Wifi Hotspot- For real time VRS service

• Trimble GeoXH 6000 / Geo7X- High accuracy- GPS , GLONASS- Built in camera- Optional laser rangefinder (7X)

“GNSS Locating System”

• Will be exposed to rough environmental conditions

• Most equipment will be weatherproof to an extent

• Protect your investment• Make your own case

Equipment Protection

Out In the Field• Done by inspectors• Located as installed• Process:

1. Drive to site 2. Assemble system, connect hotspot3. Collects point at location

• Positions taken at point (can pause)• Positions automatically combined• Must be level and not move

Getting the Point

• Data Dictionaries- Attributes Form- Quick and easy - Always collect locater name- Hidden attributes

- Date, time, static attributes (example unit type)• Polylines: multiple “Location Points”

GNSS Locating in the Field

Back at the Office

1. Exported / formatted using Pathfinder Office2. Rename / organize in ArcCatalog3. Append to ArcGIS 4. Draw line features, rotate point features5. Inspect locations6. Inspect & modify attributes

The Benefits• Increased Productivity

- Fast - Makes GIS data more valuable- Saves future time- Less errors

• 4” Accuracy!- Correct relevant to other assets- Data quality

Other Great Uses!

• “Reverse locating”- Navigate to a previously located asset

• GNSS Design Locating- We can use it to locate other infrastructure prior to

design- Data exported to CAD .dwg

• Increase investment value

Training Your Staff (as Locators)

• Emphasize accuracy• Write a manual• Train personally• Train in the field• Have patience• Takes practice• Inspect work

Advice• Won’t make you a surveyor

- Won’t replace licensed professional surveyor• Use as a “definite” location

- Avoid manually moving• “Our assets don’t need 4” accuracy, the assets themselves are bigger then that!” - Correct position in relation to other assets

• “Our aerials aren’t even that accurate!”- Do it right the first time- Everything else will catch up

“If you do not know where you're goingYou might end up somewhere else”

-Toby Keith

Don’t let your assets end up somewhere else on your map!

Any Questions?

Daniel J. Yaw JrEngineering and GIS Technician

North Penn Water AuthorityLansdale, Pennsylvania

LinkedIn.com/in/DanielYawJr