New adjunct to deflection measurement - deflecdas captures deflection bowl curvature automatically

Recent developments in the New South Wales department of main roads (DMR) with electronic instrumentation have greatly simplified the operation and increased the accuracy of deflection bowl testing. Development of the deflectolab truck based automated system and reinstrumentation of the deflectograph with computer based data acquisition systems are two recent examples. However, the manual benkelman beam has long been the major device for manually measuring pavement deflection in Australia and has been the most commonly used test by the DMR. The deflecdas is a portable electronic data acquisition system to record deflections. It employs a rangefinder to monitor the distance moved by the truck and transducers to measure the deflection. Up to ten points along the deflection bowl are recorded. There is no physical connection between the trolley mounted deflecdas and the truck and either one or two beams may be used simultaneously. Savings in labour and improved safety are additional benefits. These developments enable improved accuracy with the investigation of deflection bowls and analysis of the radius of curvature of pavements. Analysis of results recorded during trials are discussed and highlights the limitations of mechanical dial gauges and traditional testing procedures in measuring all but maximum deflection. Revision of the test method is being undertaken to overcome some of the shortcomings (a).