The qmoem-lpmtpm measures rails worldwide

A product developed as part of the qmtoem program for the company SPENO International SA
A customer product
The LPM TPM embedded system
Measuring the rail to automate its maintenance

Speno designs, develops, manufactures, operates and sells machines for reprofiling rails on common track and in track switches.

In order to carry out the operations optimally and to document the reprofiling, geometric measurements of the rail are taken. The LPM TPM system is in charge of these functions, it is composed of a hardened data acquisition system (EN 50155 certification) and software for acquisition, processing and generation of reports.

On-board rail measurement system for Speno

qmt has developed and industrialized, as part of its OEM program, the LPM TPM product for rail profile measurement. The systems are installed in grinder trains which relays the maintenance of railways around the world


The name transverse profile corresponds to the part of the rail potentially in contact with the wheel on a section orthogonal to the direction of the rail. The longitudinal profile is defined as the variation in height of the rail - wheel contact point relative to a reference along the axis of the rail. Wear of the rails appears a) on their transverse profile, in which case it is wear by friction of the edge of the wheels on the rail (mainly in bends), or by creep of the rail if excessive loads are placed in circulation; b) on their longitudinal profile, forming undulations whose amplitude increases with each passage of railway convoys (mainly in the acceleration and deceleration zones).

The correction of transverse and longitudinal profiles is essential for the safety of rail traffic (holding, adhesion, guidance etc.), to reduce track maintenance costs (the less worn the profiles are, the less they wear), and finally to reduce vibration problems (loss of traction energy, reduction of noise emitted by the passage of a convoy, increase in passenger comfort).

The developed measuring system is used to determine the transverse and longitudinal profiles on the train which carries out rail correction by grinding. It indicates to the conductor the areas and intensity of the grinding. This system is made up of five subsystems: determination of transverse profiles by laser (KLD), comparison and management of transverse profile measurements (MPT), determination of longitudinal profiles by mechanical height sensors positioned on a rolling cart (MPL), a supervisor and a test and calibration bench.


As in any engineering project, the primary objective is to obtain the greatest number of reliable functionalities for a minimum investment. The industrial context also imposes ruthless reliability criteria and minimum downtime, and therefore troubleshooting. Thus, in a single development, several pseudo-independent and inter-communicating subsystems were developed using the solutions proposed by National Instrument.

Longitudinal measurement module (MPL)

This subsystem integrates the acquisition of heights measured by sensors in contact with the rails, processes the data to display useful information to the conductor, records them, then regenerates them on a plotter in order to have a paper copy of the measurements . This system must be able to be autonomous, print data coming from another identical subsystem, or work with the supervisor. This module has no output screen or keyboard.

Transverse Measurement Module (MPT)

This subsystem is made up of the laser system and the MPT management system. The MPT receives data from a profile measurement sensor and compares it to reference profiles stored in a library to indicate which grinding wheels to use (and at what depth) to correct the profile. It then prints the transverse profiles on a printer. This system must also be able to stand alone or work with the supervisor.

Supervision module

This subsystem allows you to configure the MPL and MPT modules, display their measurements "on the fly", possibly supervise other systems present on the train. It must be able to be stopped without disrupting the operation of the two subsystems.

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Solution according to specifications


Custom product
industrialized by qmt