Methodology for Selection and Analysis of Representative Test Roads Required for Vehicle Durability Evaluation

Abstract

Measurement of customer usage loads is one of the essential and critical activity for evaluation of vehicle durability. The customer usage loads are measured on representative public roads of finite lengths, typically for about 500 km to 1000 km consisting of a mix of different road types. It is always a big challenge for the test engineer to make sure that these selected road patches are good representatives of the diverse road conditions of the target market. In this paper, a methodology is presented for the selection of these test roads, with the use of objective road roughness values (in terms of International Roughness Index –IRI). Detail study was carried out to analyse the best-fit probability distribution model for road roughness values, and the lognormal (three-parameter) distribution model is observed to be the best suitable model. It is shown that this model provides a better objective definition and classification of customer usage of the target market. The proposed methodology is generic, vehicle independent, and objectively helps to select the best representative test roads with 95% confidence. Thereby also helps in optimising the cost and time of the service load measurement campaign.