The load-bearing capacity of the existing pavement structure is determined on the basis of deflection measurements. Measurement of deflection (deflection) of the pavement structure is performed with a deflectometer with falling load FWD.
The measurement is performed at measuring points (cross-sections), usually in the direction of the right wheel, observing in the direction of movement, on each traffic lane separately, at the appropriate distance (measuring interval is usually 50 m). 3 measurements (strokes) are performed at each measuring point. The measurement is performed using the appropriate dynamic force that is transmitted to the road via a circular plate with a diameter of 300 mm. Deflections are measured with geophones placed in the center of the circular plate and at distances of 200, 300, 450, 600, 900, 1200, 1500 and 1800 mm from the center of the circular plate.
During the measurement of deflections, in addition to measuring the temperature of the pavement surface with a sensor on the deflectometer, direct temperature measurement is performed according to the procedure given in the document “LTPP Manual for Falling Weight Deflectometer Measurement Operational Field Guidelines”, Version 3.1, August 2000, prepared by FHWA-LTPP Technical Support Service Contractor LAW PCS.
MHM-project d.o.o. Novi Sad owns a deflectometer with falling load FWD DYNATEST (FWD 8002-219), which was calibrated by the Danish manufacturer DYNATEST.
In the period from 2018, we measured deflections on more than 500 km of highways and state roads of the first order in the Republic of Serbia and on state roads in Montenegro.