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Track geometry assessment with PUPIL


For many years, ProRail (the Dutch Infrastructure Manager) used a previous method to assess the rail network's track geometric quality.

This approach (based on assessment of the amplitudes of track geometry signals such as Level or Alignment) also appeared to have some serious drawbacks and was not considered suitable to assess more complex defects (such as combined defects or cyclic deviations).

Once detected, such are the complexities of every case it could often be uncertain what the follow up measure should be. Should repair be arranged? Was a speed restriction put in place? Or should the line even be closed? 

As a result, Ricardo was requested to develop a new track geometry assessment module.



We used an approach based on calculated vehicle reactions (‘Vehicle Response Analyses’). This is the most direct way of judging if track defects could be tolerated or repaired.

Using a digital twin of the track and the vehicles on the network, the dynamic response of the vehicles is calculated as they virtually run over the track.

In this way, 'PUPIL' identifies safety critical locations in the network, provides recommendations for correction, and provides a safe speed that can be used for a temporary speed restriction.

The results from PUPIL are transferred to the ‘BBMS’ monitoring database, providing easy access to maintenance and asset management teams.

Since its implementation in 2002, PUPIL has been continuously updated with new functionalities, including new vehicle models added to the database. 

In 2019, a 10 year framework agreement was settled between ProRail and Ricardo to cover all development and support services on PUPIL.



ProRail uses PUPIL as the leading tool in securing the safe operation of the track and providing the input for the corrective track maintenance.

Since the introduction of PUPIL, there have been no track geometry related derailments due to cyclic top on the sections analysed with PUPIL. With other benefits summarised as:

•    No derailments
•    No unnecessary speed restrictions
•    More ratio behind limits
•    Concrete expert judgement
•    Sustainable track

=> More info on PUPIL

=> More info on Vehicle-track interfaces



Key Services

Vehicle Track Interaction

Start date




Ricardo Personnel Involved

Edward de Jong



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