Monitoring lateral track irregularity from in-service railway vehicles

Abstract

Maintaining the alignment of railway track is vitally important for the smooth and safe passage of railway vehicles. Poor track alignment can result in poor ride quality, flange contact, or even flange climb. Accurate horizontal track geometry can be measured using a dedicated track recording vehicle or from a full track geometry recording system mounted on an in-service vehicle. This paper describes the use of sensors mounted on the bogie of an in-service vehicle to estimate the mean track alignment without the use of optical or contact sensors. In principle, either bogie lateral acceleration or yaw rate can be processed to give an estimate of mean lateral track irregularity, but a yaw rate gyro provides consistent estimates down to lower vehicle speeds than does an accelerometer and does not require compensation for the effects of bogie roll. An improved estimate can be obtained by inverting the dynamic relationship between the mean track alignment and the bogie yaw motion. This is demonstrated with results from a Class 175 vehicle. Continually monitoring the lateral response of a bogie on an in-service vehicle, using only a yaw rate gyro, can provide data enabling the prioritization of maintenance operations.

Perspectives on railway track geometry condition monitoring from in-service railway vehicles

“…A large number of sensors were attached to a Tyne and Wear Metro (heavy metro in Newcastle, UK) to observe track geometry from an in-service vehicle. Some results from this trial were published in [4][5][6]17]. A system based on an inertial measurement unit (IMU) alone has been trialled on Merseyrail (a heavy metro in Liverpool, UK) and also is in use on the Southern network in the UK as part of a third rail condition monitoring system.…”

“…Some effort has gone into turning sensor data into pseudo-geometry, that is, the geometry as experienced by the bogie ignoring the primary suspension. [5,6] London Underground experimented with accelerometers on the bogie and body of metro vehicles where the acceleration itself was viewed against distance along the track. [7] There was no attempt to reconstruct geometry.…”

The behaviour of railway level crossings: Insights through field monitoring

“…An inertial measurement system is attached to a bogie to determine the orientation and trajectory of the bogie. From this information the left and right rail vertical geometry can be inferred (Weston et al, 2007). As the bogie is separated from the rails by the primary suspension and its movement driven by both the leading and trailing wheelsets on the bogie, the left and right rail geometry are estimated with some error.…”

Wheel-Rail Profile Condition Monitoring

“…The suspended mass is assumed to be fitted with a lateral accelerometer. It is noted that inertial sensors will require a degree of filtering due to the presence of noise and will also drift from their offset in time, so the quality of information gathered in simulation can not be expected in reality, Weston et al (2006). An assumption is also made that the lateral alignment and the gauge width variation of the track is known.…”