An appraisal of mass differences between individual tyres, axles and axle groups of a selection of heavy vehicles in South Africa

Abstract

In road design, accurate quantification of traffic loading remains a challenge. Research in South Africa with the Stress-In-Motion (SIM) system has concentrated on interaction forces between slow-moving tyres and the textured SIM device. A field study of 2 666 heavy vehicles (HVs) with Gross Combination Mass, (GCM) > 3 500 kg was conducted, where the mass (or weight) of each tyre (approximately 47 242 tyres (or wheels)) was measured. The measurements were done at slow speed over the SIM device on a rigid concrete platform. Valuable data sets in terms of inter-wheel and axle unit-mass variation were collected. The overall finding is that assumptions in road design of equal load sharing between all tyres, axles and axle groups for HVs are challenged, since unequal load sharing were identified and statistically quantified in this study. It is recommended that this finding be included for ensuring road pavement design optimisation.