Vehicle reactions versus track geometry

For assessment purposes the total range of relevant wavelengths for differential settlements is split up into a number of wavebands in accordance with vehicle response characteristics to deformations in the track geometry and the potential of maintenance machines to correct the track geometry. The measurement signals produced by recording cars are analyzed by calculating the standard deviation per waveband and detecting the exceedence of particular threshold levels. The major problem in analyzing and interpreting these signals is how the results of individual signals should be combined to one overall result. The best practical solution is to normalize the standard deviations and take the largest one as the decisive one. This is purely an empirical approach in which a theoretical basis is lacking. The one solution to combining the different geometrical components is via vehicle response. This approach is discussed.<>