Effectiveness of ECE R66 and FMVSS 220 standards in rollover crashworthiness assessment of paratransit buses

The main objective of the presented study was to compare the effectiveness of two standard test procedures for evaluating bus roof integrity: the dynamic rollover test according to UN-ECE Regulation 66 (ECE-R66), and the quasi-static symmetric roof loading according the Federal Motor Vehicle Safety Standard 220 (FMVSS 220). Both tests were applied to a selected Paratransit Bus. The investigation was carried out primarily using a numerical study backed up by experimental validation tests on components and full scale rollover tests. A sensitivity analysis using LS-OPT? was performed to identify the most important structural components influencing the response of the bus in these two tests. The results obtained from this study show that the final outcome of the crashworthiness assessment of the selected paratransit bus depends on the selection of the evaluation standard. Although the two tests are used for the same purpose of roof integrity evaluation, their results are divergent and may lead to different conclusions. The paper presents a discussion on the effectiveness of both standards in evaluating the rollover crashworthiness.