Influence of tractor-trailer interaction on assessment of road damaging performance

The influence of dynamic interaction between tractor and trailer on the assessment of the road damaging performance of heavy goods vehicles is investigated using simple mathematical models. Tractor and trailer damage indices are used to quantify the 'in-service' road damaging performance of a simulated fleet of vehicles with parametric variations typical of highway traffic in the United Kingdom. Simulated results of assessment tests on individual tractor-trailer combinations are correlated with the performance of the simulated vehicle fleet. The main aim is to establish the characteristics of a 'standard' semi-trailer to be used in the assessment of tractors, and a 'standard' tractor for testing semi-trailers. It is found that measurement of suspension 'frequency' gives the poorest correlation with the damage indices, while the 'dynamic aggregate force coefficient' gives the best correlation. Correlation achieved when assessing trailers is higher than when assessing tractors. Optimum specifications for standard test tractors and trailers to maximize test accuracy are determined.