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UIC comfort tests - VTI

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Note that very high values of lateral acceleration have been recorded (up to2.08 m/s 2 ), even with the train operating with 80% tilt compensation, when the tiltsystem should be compensating for most of the lateral acceleration. Closerexamination shows that the highest values of acceleration are all recorded in theleading vehicle, where the tilt system response might be expected to be worse.5544Scaled Votes32Scaled Votes321100.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0Lateral jerk (0.1s base)80% compensation 60% compensation 40% compensationNon-tiltingBest fit00.0 0.5 1.0 1.5 2.0 2.5Lateral acceleration (0.1s base)80% compensation 60% compensation 40% compensationNon-tiltingBest fit5544Scaled Votes32Scaled Votes321100 5 10 15 20Roll acceleration (0.1s base)80% compensation 60% compensation 40% compensationNon-tiltingBest fit00 1 2 3 4 5 6 7 8Roll velocity (0.1s base)80% compensation 60% compensation 40% compensationNon-tiltingBest fitFigure 11-2 Scatter plots – votes against individual parameters (from left upperto right below: Lateral jerk (0.1s) Lateral acceleration (0.1s), roll acceleration(0.1s) and roll velocity (0.1s)).The spread of data clearly justifies the decision to test with 40% and 60% tilt aswell as 80%.11.1.7 Relationship between parameters – simple transitionsAs well as understanding the relationships of the measured parameters to therecorded votes, it is also important to understand the relationships of the parameterswith each other. If two parameters are strongly correlated with each other,then including both in the same multiple regression will give invalid results.The P CT parameter is derived directly from three of the individual parametersused in this study, so it can only be used in a regression with N’ VA , and not withany of the individual parameters.64 <strong>VTI</strong> notat 56A-2003

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