Study confirms that sleeper pads reduce life cycle costs

Getzner Werkstoffe presents research findings at InnoTrans

22.09.10

Graz/Buers/Berlin. A recent study by the Graz University of Technology reveals that sleeper pads reduce rail track life cycle costs. Getzner Werkstoffe presented the findings to an audience of experts at the InnoTrans trade fair in Berlin – sleeper pads significantly extend track lifespans while substantially reducing maintenance costs.

Rising traffic levels and faster trains are placing an increasingly heavy burden on tracks and points, as reflected in significant signs of deterioration and higher track maintenance spending. The study by the Graz University of Technology, entitled Wirtschaftlicher Nutzen von Schwellenbesohlungen (Economic benefits of sleeper padding) or WINS, compared the behaviour of tracks fitted with sleeper pads and those without. It delivers scientific proof that the installation of pads, such as Getzner’s SLB 3007G and SLS 1308G models, significantly reduce signs of deterioration. Sleeper pads provide protection for the ballast – the critical element in ballasted track construction. The researchers reached this conclusion with the help of data models and long-term analysis of the Austrian Federal Railways’ entire track network.

Findings highlight economic benefits

The study involved examination of about 1,500 cross-sections of track. “Sleeper pads help to extend maintenance intervals and the useful life of the superstructure. This has the effect of substantially reducing superstructure life cycle costs, despite the rise in total investment,” explains Prof. Peter Veit of the Institute for Railway Engineering and Transport Economics at the Graz University of Technology. Assuming daily track loads of 70,000 gross tons, the statistics suggest that cost savings of one-third and an internal rate of return of 16 percent are achievable. The findings also indicate that the cost-effectiveness of sleeper pads increases in line with track loads.

Lower superstructure costs

Installing sleeper pads lead to a reduction in track closures of around 50 percent, while also extending the service life of the tracks by 25 percent. Padding combines the benefits of wooden sleepers with the advantages of the conventional prestressed concrete variety. It halves the rate of deterioration of the rails by preserving the ballast more effectively, as well as at least doubling tamping intervals – a major factor behind the Austrian Federal Railways’ increased use of sleeper pads since 1997. “On the whole we can say that sleeper pads are a technically and financially effective method of cutting total superstructure costs,” concludes Prof. Veit.

Some 980,000 padded sleepers and 350 point sections featuring Getzner technology are currently in use around the world. Getzner materials also help to significantly reduce track and ballast settling.

Advantages of sleeper padding: facts and figures

Tamping intervals extended by at least 100 %
50 % less track possessions on the line
Total service life increased by at least 25 %
Less rail corrugation in tight curves
Better track quality, and thus improved comfort
Advantages of timber sleepers combined with the benefits of prestressed concrete sleepers
Greater contact area between the concrete sleeper and ballast bed (and up to 90 % less unit pressure on the ballast)
Less ballast settling

WINS study

The world’s first statistical proof of the investment return offered by sleeper pads on the basis of a full rail network analysis in cooperation with Austrian Railways
At least a 10 % rate of return on the additional investment
The higher the track load, the more the investment in sleeper pads pays off

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