Nondestructive testing has become an integral part for evaluation and rehabilitation strategies of pavements in recent years. Pavement evaluation employing the Falling Weight Deflectometer (FWD) and the Ground Penetrating Radar (GPR) can provide valuable information about pavement performance characteristics and be a very useful tool for project prioritization purposes and estimation of construction budget at the network level. FWD deflection testing is an accurate tool for determining pavement structural capacity and estimating the required thickness of overlays and hence is an accurate tool for planning for or estimating required current and future construction budgets. GPR is the only tool that a highway agency may use to develop an inventory of pavement layers thicknesses in the most efficient manner possible. By estimating pavement layer thicknesses and stiffness properties more reliable projections of network rehabilitation strategies and needs can be established, thus resulting in cost effective use of available funds. Traditional obstacles for the use of FWD and GPR in pavement evaluation at the network level used to be expenses involved in data collection, limited resources and lack of simplified analysis procedures. This report presents Indiana experience in pavement evaluation with the FWD and GPR at the network level. A network level FWD and GPR testing program is implemented as a part of a study to overcome those traditional obstacles. This testing program included Interstate Highways I – 64, I – 65, I – 69, I – 70 and I – 74 and a number of U.S. Roads and State Routes. It is concluded that network level testing employing the FWD and GPR is a worthwhile, technically sound program that will provide a baseline of structural capacities of in–service pavements in Indiana. Periodical generation of necessary data will be useful for determining how best to quantify structural capacity and estimate annual construction budget. FWD data on 2200 lane miles of the INDOT network is recommended annually for network level pavement evaluation. Only three FWD tests per mile are recommended. This amount of testing can easily be conducted in one testing season. The information collected will allow the equivalent of 100% coverage of the whole network in 5 years. GPR data is recommended to be collected once every 5 years (if another thickness inventory is needed), after the successful network thickness inventory conducted in this study. GPR data collection is also recommended at the project level and for special projects. Both FWD and GPR data is recommended to be used as part of the pavement management system (together with automated collected data of international roughness index, IRI, pavement condition rating, PCR, rut depth, pavement quality index, PQI, and skid resistance).

Report Number



pavement layer thickness, FWD, GPR, backcalculation of layer moduli, deflection, layer coefficients, effective structural number, remaining life, reliability, factory of safety, SPR-2408

SPR Number


Project Number


File Number


Performing Organization

Joint Transportation Research Program

Publisher Place

West Lafayette, IN

Date of this Version