The Integrated Use of GPR and Conventional Methods for Continuous Pavement Condition Investigations: A Case Study of the QEW Rehabilitation and Widening Project

The Queen Elizabeth Way (QEW) through St. Catharines, Ontario, was originally constructed in the 1930’s as a four-lane divided highway with concrete pavements and grassed median. Through the 1950’s and 1960’s, many of the original at-grade intersections were replaced with grade separated interchanges and the Garden City Skyway was constructed to facilitate travel over the Welland Canal. This portion of the QEW has been resurfaced with asphalt concrete overlays a number of times since the 1950’s with the most recent one being carried out in 2004. However, very limited historical records exist for the pavement structure within this heavily trafficked section of QEW. Functional and structural condition investigation of the existing pavement was undertaken in 2005 and consisted of a visual condition survey of the paved surfaces, soils investigation, asphalt coring, a Falling Weight Deflectometer (FWD) survey and a Ground Penetrating Radar (GPR) survey. Approximately 120 lane kilometres of GPR data were collected to delineate the extent of various pavement structures and estimate type and thickness of the layer materials within each pavement structure. This paper presents the results of the integration of conventional investigation methods (visual condition survey, boreholes, and asphalt coring) with GPR to generate detailed pavement condition information which was used in developing cost-effective pavement rehabilitation measures for a section of this important traffic corridor. Comparison and correlation of the different data types are presented to demonstrate the effectiveness of the GPR as a supplementary tool to conventional pavement condition investigations in identifying anomalies in the pavement structure and more importantly in reducing the uncertainty in locating changes in buried pavement structure.