Road and track irregularities: measurement, assessment and simulation

Abstract

Road and track irregularities have an important influence on the dynamic behaviour of vehicles.Knowledge of their characteristics and magnitude is essential for the design of the vehicle but also for comparable homologation and acceptance tests as well as for the planning and management of track maintenance. Irregularities of tracks and roads are regularly measured using various measurement technologies. All have advantages and weaknesses and require several processing steps. Characterisation of irregularities is done in the distance as well as in the wavelength domain. For rail irregularities, various distance domain description methods have been proposed and are in use. Methods have been analysed and compared with regard to their processing steps. Several methods have been analysed using measured irregularity and vehicle response data. Characterisation in the wavelength domain is done in a similar way for track and road irregularities. Here, an important issue is the estimation of the power spectral densities and the approximation by analytical formulas. For rail irregularities, periodic defects also play an important role. The use of irregularities in simulations requires various processing steps if measured irregularities are used, as well as if synthetic data are utilised. This paper gives a quite complete overview of rail irregularities and points out similarities and differences to the road.

Dynamic investigation on railway vehicle considering the dynamic effect from the axle box bearings

“…According to the power spectrum of random track irregularity, the amplitude and phase of the spectrum are obtained by the periodogram method, and then the time-domain simulation sample of track irregularity is obtained by an inverse fast Fourier transform (IFFT). 25,26 According to the numerical simulation method of a track spectrum, the track irregularity sample in the time domain is obtained at the speed of 350 km/h, as shown in Figure 4. For a vehicle-track coupled dynamics system with multiple DOFs and strong nonlinearity, the improved Newmark's method 27,28 was used to solve the problem efficiently and quickly.…”

Overview on the DLR RailwayDynamics Library

“…The user may select four different geometrical types of irregularities (vertical, lateral, crosslevel and gauge) from a number of predefined spectra that are taken from railway vehicle textbooks or papers, e.g. (Frederich, 1984) or (Haigermoser et al, 2015).…”

Comparative Analysis of Axlebox Accelerations in Correlation with Track Geometry Irregularities

“…The wheelsets and bogies suffer significant acceleration, the forces required for their displacement ultimately dominate the dynamic forces between the railway vehicle and the track. [3] In this article the relationship between the acceleration of the wheelset and the track irregularities recorded by track geometry measurement is analysed. Vertical irregularities are often caused by an inhomogeneous longitudinal subgrade stiffness/damping distribution.…”