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Published on September 02, 2020

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Rail track diagnostics: an essential step to monitor the state of the network and plan maintenance requirements

Maintenance is a strategic factor for the proper functioning and long-term viability of a transport network. Changes in the condition of the network must be monitored to plan and control budgets and the impact of maintenance and replacement operations.

Asset Management Rail

- Crédits : Egis – Gilles Parent

Diagnostics provide an instantaneous and objective snapshot of the state of the network, which can be monitored regularly and objectively. They form an essential basis for the establishment of an appropriate programme of operations.

They may focus on a particular sector or relate to the entire network. Their purpose is to record the condition of rails, switches and crossings, but also of track bed structures and surfaces.

Assessments can be conducted in a number of ways:

  • A survey conducted on foot with visual analysis of defects,
  • Recordings of track and switch geometry,
  • Precise measurements of rail profile wear and measurements of switch components,
  • Observation of switches and crossing movements.

Mobile devices can also be used to record data with their location.

Railway track diagnostics are essential to check the precise condition and evolution of the network's infrastructure; in so doing, they make it possible to formulate a replacement strategy and plan works, taking into account operating requirements.

As regards metallic parts (rails and switch parts), based on the data resulting from the diagnostic, several strategies can be chosen:

  • Rail overlaying: depositing a new layer of metal on worn rails to extend their service life; in general, rail overlaying is decided upon and controlled by the operator themselves. This is an operation carried out at night, with no impact on transport services.
  • Total replacement of the rails, which also involves work on the surfacing, the load-bearing structure generally being conserved or even reinforced. This work can be carried out either with a long service interruption or with services continuing throughout. In this case, the works are carried out mainly at night.


A requirement on French networks: the case of Grenoble

Egis has been involved in the Grenoble light rail network since the construction of the first line commissioned in 1987 and up to the most recently built line E. Our teams are therefore very familiar with this network and its history.

They are currently carrying out track diagnostics for the network: lines A, B, C and D as well as in the two stabling and maintenance depots. In total, more than 200 switches and 80 km of track have been meticulously examined. The surveys require approximately 15 days of walking tours, conducted in teams of two in order to ensure worker safety.

Commissioned by the Grenoble metropolitan area public transport authority (SMMAG), the diagnosis will be used to draw up the upgrading programme for the next six years (2022-2027). This mission is part of the Major Light Rail Track Maintenance programme for which Egis is managing the track part in the project management consortium formed with Ingérop.

The analysis draws on expert observations (visual and sound) together with measurements taken using specific measuring instruments: a profilometer for rail wear, a gauge rule, a calliper and a depth gauge for safety measurements.

Rail profile survey in red and comparison with the theoretical one in blue

The data is collected through the InSitu program (usually dedicated to construction supervision) installed on a tablet.

Following this diagnosis, a report will be submitted to the SMMAG, indicating in detail the state of the track and proposing an appropriate track replacement schedule.


Proven know-how: the example of the Montpelier network

In 2017, Montpellier Méditerranée Métropole (3M) wished to have a diagnosis of its transport network, currently operated and maintained by TAM within the framework of a concession agreement. Based on an inventory of its transport network, this diagnosis provides a complete and exhaustive picture of the physical condition of 3M's assets.

Drawing on operational data, precise observations and its knowledge of ageing processes, Egis produced a forecast of how the network would be likely to evolve and the track maintenance or replacement works that should be planned in the form of a multi-year programme in two phases up to 2032, with details of the associated costs and resources.


A first step in asset management

Asset management offers network managers the opportunity to be aware of their network’s condition and plan the necessary investments to guarantee the best quality of service.

Works scheduling, based on knowledge of the condition and ageing laws of rails and switches, is therefore a first step in asset management.

By building upon an internal program previously used for the road sector, Egis has developed a comprehensive solution to assess the condition of light rail assets that uses data collected in the field. It offers the use of GIS data that can be easily administered by both the manager and the maintainer. With the help of theme-based analyses, the user will be able to visualise the state of the network, generate tables summarising track deterioration and assess its severity and associated statistics. 

In brief, optimized asset management requires an accurate knowledge of the condition and maintenance history of assets and a perfect understanding of their impact on the authority's objectives, particularly safety and quality of service. Once the diagnosis has been made, maintenance recommendations are not limited to waiting for components to wear out before replacing them! Reloading operations enable the infrastructure to continue to function and postpone its renewal.


The authors

Olivier Berger,

Expert, Infrastructures and track department


Gilles Parent,

Engineer, Infrastructures and track department



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