Delft University of Technology
Faculty Mechanical, Maritime and Materials Engineering
Transport Technology

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; , TU Delft / 3mE / TT / LT.