Trackside measurement of critical zones in railway tracks

[摘要] Abrupt changes in track stiffness can occur where the ballasted track transitions from soft foundations onto bridges and viaducts, onto hard foundations and into tunnels, or at the interface between bal¬lasted track and slab track. Such interfaces between areas of different track stiff¬ness are defined as critical zones and can cause passenger discomfort, unpredictable track degradation and, potentially, track support failures. Given their nature, main¬taining critical zones is more expensive than maintaining plain line track and measuring and assessing the variations in track stiffness are critical activities in track main¬tenance and in ascertaining the quality of newly designed and built railways. Existing methods of track stiffness measurement are not sufficiently accurate and depen¬dable. Therefore, the aim of this research was to develop an innovative but rapid method of assessing track stiffness, so as to identify problems in transition zones. During her doctoral research, the author designed and built a sleeper deflection measurement system as a means of quickly assessing track stiffness. The laser-based digital system developed uses position sensitive detectors (PSDs) and a line laser. The performance of the new measurement system was verified on a private railway at Long Marston, which showed that the system was able to capture the displacement data of individual sleepers and thus the continuous movement of rails supported by 18 sleepers. Ob¬serving the train-induced dynamic deflection patterns across multiple sleepers allows a rapid assessment of the track stiffness and provides the information that is necessary to manage the stiffness variation around transition zones.

[发布机构] University:University of Birmingham;Department:School of Engineering

[关键词] T Technology;TF Railroad engineering and operation