Apart from regular wheel wear such as decreasing wheel diameters and reduced flange thicknesses and heights, wheel flats (WF) and oval wheels (or OOR, Out-Of-Roundness) are the most common wheelset problems for railwayvehicles. Within the FP7 Research Project “ Saferail” , APT has developed an innovative wheelset Monitoring systemso-called “ Wheel flat and Out of Roundness Monitoring (WORM) system” . The Monitoring system is installed on thetrack and is based on the vibration signals measured during the passage of trains. The main advantages of vibrationsignals are the short measurement time of just a few seconds, and the very limited number of sensors to be installed. As a consequence, the track space required for the installation of the equipment is very limited and thus the associatedinstallation cost is significantly reduced. Early detection of wheel flats combined with appropriate corrective actionnot only contributes to lower track stresses and wear, but also results in a longer wheel life. The WORM system reportsall measured vehicles via a web interface so no user software installations are necessary. A historical overviewof measurements and alarms can easily be retrieved from the proposed system. Immediate alerts can be programmedto be sent by email or text message. These advantages make the APT-WORM system as a strong device to increase theservice life of the wheel and decrease the maintenance cost by optimizing the maintenance intervals.

Condition Monitoring is the foundation of a Condition based maintenance (CBM). To relate the information obtained from the Condition Monitoring to the actual state of the system, it is usually required a stochastic model. On the other hand, considering the interactions and similarities that exist between CBM and statistical process Control (SPC), the integrated models for CBM and SPC have been developed. These models apply Control charts as a Condition Monitoring technique, and the inference about the operational states of the system is based on the collected information about the quality of the produced items. Finally, it is decided whether to implement certain type of maintenance actions. This paper describes the application of multivariate Control charts as a Condition Monitoring technique for CBM purposes. To this end, an integrated model is developed, while it is used a chi-square Control chart. Also, to determine the inspection time points, a constant hazard policy is applied.

Apart from regular wheel wear such as decreasing wheel diameters and reduced flange thicknesses and heights, wheelflats (WF) and oval wheels (or OOR, Out-Of-Roundness) are the most common wheelset problems for railway vehicles. Within the FP7 Research Project “ Saferail” , APT has developed an innovative wheelset Monitoring system so-called “ Wheelflat and Out of Roundness Monitoring (WORM) system” . The Monitoring system is installed on the track and is based on the vibration signals measured during the passage of trains. The main advantages of vibration signals are the short measurement time of just a few seconds, and the very limited number of sensors to be installed. As a consequence, the track space required for the installation of the equipment is very limited and thus the associated installation cost is significantly reduced. Early detection of wheelflats combined with appropriate corrective action not only contributes to lower track stresses and wear, but also results in a longer wheel life. The WORM system reports all measured vehicles via a web interface so no user software installations are necessary. A historical overview of measurements and alarms can easily be retrieved from the proposed system. Immediate alerts can be programmed to be sent by email or text message. These advantages make the APT-WORM system as a strong device to increase the service life of the wheel and decrease the maintenance cost by optimizing the maintenance intervals.