B.M.A. Herfkens
Beschadiging aan treinrails door vrachtvervoerders
Literature survey,
Report 2006.TL.7047, Transport Engineering and Logistics.
The past ten years the freight transport by train in the Netherlands has
doubled. As a result the current railways are used more intensively. For
this reason a number of large projects concerning the infrastructure is
necessary. One of these projects is the Betuweroute, which will be opened in
the beginning of 2007. At this moment there are still no freight carriers
who will use the Betuweroute, because the rail tax by the infrastructure
administrator ProRail is too high.
The rail tax can be based on the amount of damage by trains. For this reason
it is important for the freight carriers to know what the amount of damage
is. Damage of train rails is the consequence of two phenomena; wear and
rolling contact fatigue.
Wear, with material loss, is the consequence of an abrasive process, where
small particles between the wheels and the rails rub off the top layer. The
degree of this wear is expressed with the wear rate and the wear
coefficient. Some scientific studies have been done to predict the wear rate
and wear coefficient. The results of these studies have been used. Important
factors that play a role in the wear process are slip, hardness,
microstructure and water as a lubricant. Especially slip and water have
proven to have very large influence to the wear rate. Wear appears to
increase when the rail- wheel contact is alternatively exposed to wet and
dry circumstances.
The quantity of wear can be subdivided in roughly 3 categories; Type I, II
and III. Type I is mild wear with low wear rates. The wear is a process with
corrosion. Type II is severe wear. There are cracks and metal particles.
Type III is catastrophic wear and causes deep cracks and ploughing in the
(rail-) surface.
Rolling contact fatigue occurs with repeating loading. The material can show
plastic deformation and can eventually crack. Although there will be no loss
of material, it is possible to measure the degree of RCF. The
elastic-plastic behaviour, the crack growth and the amount of loads till a
rail breaks can give a good indication.
The model of a container train shows that mild and heavy wear appears with
wear rates between 0.5 and 1.0 * 10-4
gr / m / 10 mm contact. At train speeds
above 130 km/hr type III wear will appear. This model shows an elastic
behaviour. Therefore almost no plastic deformation will appear as a result
of this train. The critical crack length is between 0.33 and 0.60 mm. Larger
cracks will propagate and lead to fracture.
The model for a heavy haul train gives a wear rate of 0.6 to
1.5 * 10-4
gr / m / 10 mm contactbreedte.
Here wear of type of I and II occurs. At speed above 110 km/hr catastrophic wear
will appear. This model causes plastic deformation and has a critical crack
length between 0.44 and 0.81 mm.
Reports on Transport Engineering and Logistics (in Dutch)
Modified: 2006.04.25;
logistics@3mE.tudelft.nl
, TU Delft
/ 3mE
/ TT
/ LT.