In-Track Wheel Measuring System (IWMS)

The Power of In-Track Wheel Measuring Systems for Modern Railways

Railway networks around the world are evolving rapidly, with increasing demands on rolling stock performance, safety, and availability. As maintenance strategies shift from time-based to condition-based approaches, the need for accurate, real-time wheel condition data is more critical than ever.

This is where the in-track wheel measuring system becomes indispensable.

Unlike portable devices or manual gauges, an in-track wheel profile measurement system is permanently installed in the track. It continuously inspects the wheel geometry of each passing rail vehicle, without stopping operations, lifting wheelsets, or modifying the infrastructure. It’s the modern railway’s solution for automated, high-volume, non-intrusive wheel diagnostics.

What Is an In-Track Wheel Measuring System?

An in-track wheel measuring system is a laser-based, fixed installation that automatically records key wheel profile parameters while the train is in motion. It uses embedded sensors and lasers to scan wheelsets as they pass over the track-mounted modules.

This embedded wheel measuring system operates in both indoor and outdoor environments and supports metro, tram, regional, and high-speed rail vehicles. Depending on site configuration, it can be adapted for variable numbers of axles and diverse wheel types.

Unlike mobile or manual systems, in-track measurement is:

• Automated
• Unobtrusive
• Highly repeatable
• Safe for continuous operation

Why Fixed-Position Wheel Monitoring Systems Matter

A fixed-position wheel monitoring system allows railway operators to achieve:

• Real-time inspection of flange wear, QR dimensions, and wheel diameter
• Comparison of data across time (wear trend analysis)
• Immediate alerts on non-compliant wheels
• Zero disruption to operational schedules

This is especially important for:

• Depots managing multiple vehicle types
• High-speed and heavy-load networks
• Maintenance hubs requiring precise before/after profiling

Key Features of In-Track Laser Wheel Measurement Systems

The in-track laser wheel measurement system delivers exceptional accuracy and repeatability, made possible through high-resolution optical sensors and calibrated algorithms.

Parameters Measured Include:

• Wheel width
• Back-to-back distance (AR dimension)
• Flange height (SH)
• Flange thickness (SD)
• Flange gauge
• QR dimension
• Wheel diameter
• Wheel hollowness
• Wheel flange offset
• Leading measurement
• AR and SB/DB dimensions (for tram/rail compatibility)

These measurements are visualized using powerful software like WheelPro, which allows trend analysis, historical comparisons, and automatic vehicle identification.

Indoor and Outdoor Flexibility

The system is available in two configurations:

• Indoor installation – perfect for metro and tram depots
• Outdoor installation – ideal for open track measurement or mainline access points

Both versions are designed to resist vibration, dust, and variable temperatures, ensuring accuracy even under harsh rail yard conditions.

Operational Benefits of In-Track Systems

• Works at speeds up to 15 km/h, adaptable to 90 km/h
• No modification to rails or vehicles required
• Integrated with vehicle databases for traceable diagnostics
• Enables full wheelset monitoring before/after reprofiling
• Reduces manual inspection time and human error
• Provides long-term wear analysis and maintenance forecasting

How It Works

• The system detects the wheel using transponder antennas or axle sensors
• Laser scanners mounted under the rails measure profile parameters
• Data is processed in real time and stored under the vehicle’s unique ID
• Wheel data is automatically compared with tolerances and historical records
• Results are exported or visualized via WheelPro software

The measurement process is non-contact and doesn’t require wheel lifting or slowdowns, making it perfect for high-throughput depots and inspection points.

Use Cases

• Depots: for intake/outtake profiling and wear certification
• Metro/Light Rail: for automated tracking of wear in dense urban systems
• High-Speed Rail: for dynamic profile monitoring at access control points
• Maintenance Yards: for before/after wheelset profiling during reprofiling