Non-contact deflection measurement at high speed

Traditional stationary or low speed deflection measurements become problematic on roads with high traffic densities. Traffic safety is decreased when survey vehicles like low speed deflectographs or stationary falling weight devices carry out measurements on highway networks. This paper describes how the Greenwood High Speed Deflectograph applies Laser Doppler Technology to provide information about pavement response to traffic load. The information obtained is the deflection velocity, the vertical velocity of the pavement surface due to a wheel load. The results from the tests show that the High Speed Deflectograph provides repeatable data comparable to similar information obtained with the Falling Weight Deftectometer.