Wheel Profile Monitor 


The Wheel Profile Monitor (WPM) is an effective tool for wheel maintenance management. The WPM is installed on the track and performs measurements of the wheel profile for every wheel of a train passing the installation site at steady operating speeds. The system firstly captures images of the wheels and process them with advanced machine vision algorithms to measure the key wheel parameters including:


   - Flange height

   - Flange width 

   - Hollowing 

   - Back to back dimension 

   - Inner and outer rim thickness

   - Wheel diameter and differential

   - Wheel profile trace


WCS have developed an advanced triggering method that allows the system to precisely capture the image of target while keeping power consumption to minimum.

The system consists of Image Capture Units (ICU), set up in such a way that the entire profile of the wheel head is captured. The ICUs use a high shutter speed rate controlled by high speed strobe lighting. The cameras and strobe lights are synchronized and triggered by digital packets, which means that the images are never misaligned.

The system monitors the movement of each axle, bogie, and wagon to ensure the precise triggering. 

WPM system uses the true images for profile measurement which enables the 

verification of the measurements through manual auditing, and therefore yield higher accuracy. 

Measurement accuracy is not affected in the situation of distortions caused by train unusual movement. WPM does not require frequent calibrations which could reduce operation cost.

The Wheel Profile Monitor has been accredited by the Association of American Railroads to Six Sigma for Gage Reliability and Repeatability.


System installation 

Wheel profile measurement 

Wayside hardware sensors layout with Image Capture Units (ICU), flash units and wheel sensors. Integrated Video Capture module and Industry computer installed in the rack are responsible for image data process and calculation  

Wheel image capturing 

Precise light triggering and camera capturing of wheel movements

Monitoring the movement of each axle, bogie, and wagon to ensure that precise triggering is possible. The flash unit generates pulse energy up to 1.5 Joules over 33uS to minimise the power consumption 

Profile measurement

Reference Marker provides reliable and accurate measurements

The reference marker (T-targets) provides a fixed calibration point which eliminates error that would otherwise be introduced by rail and wheel movement.