LATEST USE OF GROUND PENETRATING RADAR FOR RAILWAY APPLICATIONS Damien Foun, Geotechnical Engineer, Civil Engineering Services, QR

LATEST USE OF GROUND PENETRATING RADAR FOR RAILWAY APPLICATIONS Introduction Recent QR developments with GPR testing (since early 2004), Development of GPR by QR during 2006, Latest GPR developments outside QR

INTRODUCTION Ground penetrating radar (GPR) - description QR currently uses Groundprobe Pty. Ltd. and GBG Australia Pty. Ltd. for GPR testing services. GPR testing can provide valuable information for Track upgrade projects, Assessment of track sections for track maintenance, Specialist projects.

INTRODUCTION

DEVELOPMENTS SINCE 2004 Improvements in determining positions of GPR testing information with GPS: Previously a measuring wheel was used, GPS referenced to track kilometrage, though GPS co-ordinates of track kilometrages required. Data positioning accuracy further improved by using video cameras.

DEVELOPMENTS SINCE 2004 For GPR testing for measurement of ballast depth, GPS co-ordinates added to video image and GPR traces.

DEVELOPMENTS SINCE 2004 Presentation of ballast depth information (base of ballast layer) using 3-D surfaces. 3-D surfaces clearly indicate the locations of ballast depth features.

DEVELOPMENTS SINCE 2004

QR RESEARCH DURING 2006 During 2006, QR have been investigating the use of GPR equipment for the following applications: APPLICATION CURRENT METHOD BENEFIT OF USING GPR Measurement of ballast fouling levels Ballast sampling, then laboratory testing Continuous testing Laboratory testing not required. Locating buried objects within ballast - Prevent damage to ballast cleaning equipment.

QR RESEARCH DURING 2006 APPLICATION CURRENT METHOD BENEFIT OF USING GPR Locating cracks in timber sleepers Visual inspection Test at possibly higher speeds Locating cracks in formations Trenching Continuous testing along track sections Measuring ballast depths with GPR at high speeds (up to 60 km/h) also investigated.

QR RESEARCH DURING 2006 Methodologies of main two objectives. Measurement of ballast fouling levels Test a track section with GPR equipment, Obtain ballast samples and perform PVC testing (at approximately the same time as step 1), Correlate GPR signals with PVC test results to develop an equivalent PVC result for particular GPR signals.

QR RESEARCH DURING 2006 Locating objects in ballast Bury several objects under a track section, Perform GPR testing.

QR RESEARCH DURING 2006 3-D radar planned for field trials. 3-D radar attached to frame for high speed testing (not in contact with rails).

QR RESEARCH DURING 2006 3-D radar not successful. Therefore, alternative GPR equipment trialled for measurement of ballast fouling levels.

QR RESEARCH DURING 2006

QR RESEARCH DURING 2006 Radar signal interference from steel and timber sleepers significant, Further trial with GPR horn antenna rotated 900 may be performed, 3-D radar may be trialled again at a later date after technology has been proven.

OVERSEAS GPR DEVELOPMENTS Presenting GPR data, video and maps in a single display, Testing speed of up to approximately 160 km/h possible.

SUMMARY Recent developments Improvements in positioning method and accuracy, Use of 3-D charts. Desirable applications Measurement of ballast fouling levels, Locating objects buried in ballast, Locating cracks in timber sleepers and track formations.

SUMMARY GPR testing at 60 km/h also desirable. Overseas developments Presenting GPR data, video and maps in a single display, Testing speed of up to approximately 160 km/h possible.

LATEST USE OF GROUND PENETRATING RADAR FOR RAILWAY APPLICATIONS Questions ?