Speckle techniques are investigated for the characterization of pavement surface microtexture, particularly, height variations from one up to about ten micrometers in amplitude. Using the scalar diffraction theory of Kirchhoff, some simulations of the speckle contrast were carried out to bring out some patterns in case of a subjective speckle whose grains are not resolved by CCD photodetectors and in the case of a two-scale surface texture. We deduce the possibility of characterizing the fineness of the microtexture or its evolution versus wear modifying. The method is also experimentally applied to some reference surfaces (abrasive papers with various finenesses) and some models ofpavement surfaces at various steps of wear.
This paper shows the way to turn a defect inherent to single-mode fiber, namely birefringence, into a prime quality for a powerful and reliable sensor. The latter is entirely devoted to Weigh-In-Motion (WIM) applications extended to complete active traffic management systems. After a brief description of the sensor and its principle of operation, the theoretical model is developed. Then, a full characterization made in both static and dynamic conditions is presented. The results obtained illustrate how it is difficult to interpret a weight measured in dynamic conditions and correlate the value with the static weight.
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