Radu Popovici from the University of Twente advises the Dutch
national rail company and ProRail to equip their trains with
sensors that measure the slipperiness of the tracks. Such measures
can reduce the number of delays and make the tracks safer,
especially in the autumn. On 19 February, the Faculty of
Engineering Technology awarded Popovici a PhD for his research into
friction on slippery tracks.
During the autumn in the Netherlands, many trains battle with
frequent delays and cancellations. PhD student Radu Popovici from
the University of Twente has researched ways of tackling this
problem. He equipped a train with a sensor that measures the
friction between the wheel and the rail. A similar sensor then
communicates to the driver whether the track is slippery or not.
Based on his findings, Popovici has advised the Dutch national rail
company Nederlandse Spoorwegen (NS) and ProRail to install his
friction sensor in their trains. 'This is a relatively simple
solution that not only makes the tracks safer but also prevents
unnecessary delays. What's more, the sensor allows us to pinpoint
to the letter which sections of the Dutch railway network are
slippery and which are not. Dutch national rail and ProRail have
expressed their satisfaction with the advice but are not yet able
to commit to implementing it'.
Friction sensor
The friction sensor measures besides the rotation speed of two
wheels (a braked wheel and another wheel) the friction. The
measurements enable those monitoring the tracks to ascertain how
slippery they are; at which point a signal will be sent to the
driver. Trains are currently running across the Dutch rail network
without this kind of sensor. This can lead to dangerous situations
if the driver does not notice that the tracks are slippery. On the
other hand, if the driver errs on the side of caution and presumes
that the tracks are slippery, he or she will drive slower, causing
unnecessary delays.
Multiple causes
Furthermore, delays in the autumn are always blamed on fallen
leaves on the tracks when this is not always strictly the case,
explains Popovici. 'Though the problem occurs in the autumn, it's
not always down to just the leaves. Other causes include the levels
of humidity, the temperature and industrial pollution.' Popovici
carried out his measurements on three sections of track in the
Netherlands: the Utrecht-Arnhem-Zwolle circuit, the Rotterdam-Hoek
van Holland line and the Roosendaal-Vlissingen line. The
measurements were taken at night, since the network is too busy
during the day to allow a test train to run.
Note to the press:
Radu Popovici conducted his research at the IMPACT research
institute and as part of the research group 'Surface Technology and
Tribology' at the Faculty of Engineering Technology. He was
supervised by Prof. Dik Schipper. This research was supported with
funding from the Dutch national rail company Nederlandse Spoorwegen
(NS) and ProRail. The research project was carried out in
collaboration with Wageningen UR, TU Delft, Iris Vision and other
businesses. An electronic copy of the thesis, entitled Friction
in Wheels - Rail Contacts, is available on request.
