Measurement of vertical geometry variations in railway turnouts exposed to different operating conditions

Turnouts are critical units in a railway system; they perform the switching procedure that allows trains to change between routes. Monitoring the track geometry of a turnout is necessary for maintenance planning and design optimisation. Monitoring is usually done by track recording cars, however, to isolate the ageing and dynamic behaviour of the track it is also necessary to study the unstressed track geometry of the turnouts. Such measurements can be used to develop degradation models to optimise maintenance and design, thereby increasing availability and reducing life cycle cost. This paper introduces a new method to measure the vertical position of the track geometry over time during non-operational conditions (unstressed) to show track degradation. The new method includes a smart system that uses relative measurement reference points to create a better accuracy and lower costs compared with fixed reference points. It evaluates various types of measurement equipment and uses levelling equipment to measure the unstressed vertical geometry of 13 turnouts located on Swedish railway lines, with three follow-up measurements over a year and a half. The turnouts were categorised into four groups: based on their accumulated capacity in million gross tonnes (MGT) and whether they were on a straight or curved main track. Surprisingly, the first three measurements showed the geometry of turnouts on the straight main track to have a vertical elevation tendency towards the mid-section, whereas the turnouts on the curved main track had a general vertical downwards bend tendency towards the mid-section. The results also showed that a higher capacity in MGT has a greater influence on track geometry changes over time.


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  • Accession Number: 01599989
  • Record Type: Publication
  • Files: TRIS
  • Created Date: May 4 2016 9:13AM