Structural capacity assessment of queensland roads using traffic speed deflectometer data

The Traffic Speed Deflectometer (TSD) is a vehicle-mounted Doppler laser system capable of continuously measuring the vertical velocity of a pavement while moving at traffic speed. The device's high accuracy, high speed, cost-effectiveness and continuous deflection profiles are useful for network-level structural capacity assessment. Consequently, the device assists in predicting accurate road rehabilitation needs and remaining service life. This paper's objective is to report on the development of a simplified methodology for the assessing the structural capacity of flexible pavements, using TSD data for screening road networks. The methodology was developed in combination with using tolerable deflection curves and design traffic loading. The tolerable deflection curves are used to design pavement overlay thickness for thin surfaced granular pavements. The existing tolerable deflection equations are based on Falling Weight Deflectometer (FWD) maximum deflection, thus these equations were redeveloped for the TSD equivalent curves. This study successfully established a detailed procedure for predicting the remaining structural life using TSD deflection data. It also established a state-of-the-art methodology for assessing the structural capacity of low traffic volume flexible pavement using TSD deflection data for sustainably managing road assets within available road maintenance funding.