Track for modern ballasted high speed railway lines typically uses continuous welded rail with continuous ballast. Continuous ballast is often specified over features involving discontinuity of track support including structural movement or expansion joints found in long railway bridges. Accelerated degradation of track geometry has been observed at these types of location, resulting in unplanned maintenance. A location was identified on a viaduct of an operational high speed railway, where a reoccurring track defect develops just following a structure expansion joint which was designed for continuous ballast. Trackside monitoring techniques have been used to capture the response of the track in the vicinity of the defect and of the bridge spans on either side of the structure expansion joint under normal operational conditions and to evaluate a typical maintenance process. This gave insight into the performance of the track, demonstrating that the defect was due to voiding and recurring as maintenance was ineffective at filling these voids. Monitoring also provided evidence of bridge behaviour which could have an adverse effect on the ballast over the joint and may be responsible for the original formation of the defect. Evidence from this monitoring has given new insights into the reasons for defect occurrence and recurrence allowing for a more informed approach to specifying maintenance, given the knowledge that there is little that can be done to alter the behaviour of the viaduct structure without major intervention.
展开▼
