EFFECT OF OVERLOADING AND INTRODUCTION OF TANDEM AXLE TRUCKS ON PAVEMENT LIFE

This paper presents the results of a study of axle loads, which showed that, in India, both single and tandem axles were exceeding their legal limits considerably, leading to extensive road damage. Its first section outlines the current Indian axle load limits, describes the spectrum of axle loads and overloading and their effects on pavement performance, and the economics of lorries with different axle types. The study's main objectives were to: (1) determine vehicle damage factors (VDF) from axle load spectrum data; (2) assess the effect of vehicle overloading on pavement performance; and (3) study how the introduction of tandem axles could increase pavement life. Four study locations for the detailed axle load survey were selected on Indian National Highways. The wheel weighing equipment was developed by the Department of Civil Engineering at Bangalore University, and made by Syscon Instruments, Bangalore. The two axles of a tandem pair were assumed to have equal loads. The field data were analysed, using actual field data of the axle load spectrum, and by converting different proportions of overloaded single rear axles into tandem axles. VDFs were computed from field data, using simple formulae, and a mathematical model was used to estimate pavement damage and especially road surface deflection.