"Road pavement is a valuable asset for the development of modern society, the quality of which plays a fundamental role in the safety, economy, and sustainability of the free movement of people and goods. The assessment of road pavement condition and their evolution with time is a crucial component for planning and implementing appropriate maintenance and rehabilitation activities to maintain pavement specified minimum quality requirements.
Pavement deflections measurements can be used as a quick and easy method for non-destructive determination of the structural capacity of existing pavement and evaluation of its ability to withstand future traffic loads. Pavement deflections are usually measured with Benkelman Beams, Le Croix-type deflectographs or Falling Weight Deflectometer.
In the last decades, an alternative deflection measuring solution, via deflection, velocity and acceleration measuring sensors embedded in the pavement has attracted more and more attention. Integration of sensors in the road pavement allows the assessment of the complete history of pavement response under real traffic, starting from sensor installation.
This paper will provide an overview of the sensors most commonly used for measuring deflections, linear variable differential transformers, geophones and accelerometers."

pavement deflections; linear variable differential transformers; geophones; accelerometers