Measurement of rail deflection on soft subgrades using DIC

Abstract

The measurement of track displacement during the passage of a train is an important parameter for the assessment of track condition. Digital image correlation (DIC) is a non-contact camera-based technology that can be used to measure these displacements. However, ground vibrations induced by the train can result in camera movement, adding error to the measured displacement. This paper presents a two-camera method that can account for the camera movement when measuring track displacements using DIC. The method is validated on a stationary track and then used to measure track displacement during the passage of two trains travelling at different velocities. The results of the two-camera method are then compared to the track displacements found using a low-pass filter. The two-camera method was found successfully to reduce error due to camera movement while removing the subjectivity of choosing a cut-off frequency for filtering.

Simulation of Impact Interaction of Rail Transport Carriage in a Butt Roughness Zone

“…Here the efficiency and reliability of the track design are crucial for a successful operation. A lot of modern rail track studies focus on individual aspects of design and operation, such as fatigue [21,24], ballast failure [9], driving comfort [31], noise or vibration [8,12,13,30].…”

“…It is also known, that the highest level of the ballast deposition arises under the first sleeper of a receiving rail. This is related to the fact [17,28] that in these places, the first sleeper under the receiving rail usually experiences the greatest power interaction between the carriage and the top structure of the way, due to their impact force [2,16,18,20,30,31]. Thus, the deflection of the receiving rail under the first personal sleeper tend to be an essential indicator, which corresponds to the peculiarities of the processes of static, shock and dynamic interaction of the receiving rail with the upper structure of the path in places with isolated path butt joints [5,23].…”

Performance assessment of peat rail subgrade before and after mass stabilization

“…Camera movement induced by ground vibration can occur when using DIC to measure track displacements at sites with poor quality subgrades such as peat (Bowness et al 2006). To account for this movement the two camera backsight method (Wheeler et al 2016) was used.…”

“…Using the backsight camera technique (Wheeler et al 2016), two cameras were setup to monitor the track while the other two were used as backsight cameras to account for potential camera shake due to vibrations in the soft subgrade. Figure 8 shows the camera setup used in the study as well as the field of view captured by the two foresight cameras.…”

Editorial

“…The first paper (Wheeler et al, 2016) presents a new method of carrying out digital image correlation (DIC) to remove the effect of ground vibration of the camera from measured rail movements. With ongoing advances making higherresolution digital cameras available at reducing cost, DIC is a tool that is routinely being deployed both in controlled laboratory experiments and in the field to gain insights into mechanisms of behaviour.…”