An optical displacement transducer, mounted on a vehicle-drawn trailer, has been applied to the measurement of groove depths and spacings on concrete pavements at speeds up to 10 km/h. The system uses the same equipment as that used to measure the texture depths of pavement surfaces. Various grooved surfaces were examined using the optical system and the results compared with depth-gauge measurements. The average groove depths measured by the contactless sensor are within 12 per cent of the average depth-gauge reading, except for surfaces where the grooves are badly formed. The depths of perfectly formed grooves are measured to within plus or minus 0.6 mm. The spacing between detected grooves is measured within plus or minus 2 mm at a towing speed of 10 km/h. A programmed computer, mounted in the vehicle, performs the required calculations and allows the distribution of groove depths and spacings to be printed out on completion of each measurement. (Author/publisher)
Abstract