Louisiana DOTD Ground Penetrating Radar (GPR) Data Collection: A Case Study. Ron Galos BES, GIS-AS. May 7, Fugro

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1 Louisiana DOTD Ground Penetrating Radar (GPR) Data Collection: A Case Study Ron Galos BES, GIS-AS Fugro 2013

2 Contents Menu What is GPR? Project Scope GPS Controls QC Process & Results GPR Data Process Flow Data Collection Data Processing & Initial Analysis Coring and Calibration GPR Analysis Reporting ivision Summary

3 What is GPR? Ground Penetrating Radar (GPR) is a geophysical method that uses radar pulses to image the subsurface. Non destructive testing method to obtain pavement thickness and base and subbase evaluations by detecting reflected signals. Asphalt Concrete Sub-base Pavement material and thickness reported in client specific format

4 Louisiana Department of Transportation & Development ~36,000 miles of highway Required GPR for: Use in Pavement Management System for modelling pavement performance Use in construction (highway repairs) Find thin spots Model future performance of pavement in order to plan treatments at optimum point in time

5 Louisiana Department of Transportation & Development Data collected from Sept 2010 to Apr ,245 miles collected Survey Type Delivered Miles Sensor 36,245 Pavement Distress 20,600 GPR 18,000 Asset Inventory 36,245 GPR data being delivered in 4 stages ( )

6 GPS Controls QC Process & Results GPS accuracy very important to LADOTD LSU s Center for GeoInformatics provided high accuracy GPS for 1 mile sections ARAN GPS accuracy was evaluated monthly and compared to ground truth values Control Section in Iberville Parish on east bound I-10 bridge over the Whickey Bay Outlet

7 Data Process Flow Data Collection Data Processing & Initial Analysis Coring and Calibration GPR Analysis Reporting

8 Data Collection Automatic Road Analyzer ROW Video Full POS / geometry system Full sensor data Antenna Frequency Penetration Depth 1,600 MHz 29.5 in 900 MHz 59 in 1,600 & 900 MHz antenna Scans 12 in wide every 10 in Pavement imaging system

9 Data Processing & Initial Analysis Raw GPR Data undergoes various processing steps to clean up the data in preparation for analysis Frequency filter pass Time correction Background noise removal After Processing

10 Core Location Identification Core locations are identified in the initial analysis ~1 core every 7 miles Located within major construction sections Located in areas of suitable data quality for calibration purposes

11 Coring and Calibration 1,756 cores taken since project start (3 years) Provide ground truth and used to calculate velocity Coring completed across state Coring data imported into database based on GPS location

12 GPR Analysis Construction boundaries were traced on the GPR profile, marking ( picking ) the base of the material at 0.1 miles intervals Picks are placed at construction changes and other points of interest Data quality and level of agreement with core was recorded 1 = Base of Asphalt 4 = Base of Concrete 1500 MHz Antenna Reporting Interval 900 MHz Antenna Construction Change Core log showing thickness of Asphalt and Concrete layers

13 Reporting GPR data merged into database containing all other information needing to be reported (ie. Locator, linear reference information, GPS, etc) Process and Export the reports into the specified format (Access DBF) 2nd Stage of data QC performed GPR data collected and interpreted by Fugro, hosted and visualized in the LADOTD PMS

14 ivision Visualize pavement layers in ivision alongside other data Interrogate data and display as map overlay (top left)

15 Summary GPR analysis is currently in progress All 18,000 miles of GPR data collected 8,282 miles delivered to date 4,018 miles due July ,700 miles due July 2015 When completed LADOTD will have a complete surface and subsurface analysis of their road network to go along with their asset inventory

16 Questions? Fugro 2013 Ron Galos Fugro Roadware Booth #38