Vaihteiden kehitystyö

Translated title of the contribution: Development in turnouts

Research output: Book/ReportCommissioned report


Over the years, several different problems related to turnouts safety, stiffness and actuation have been identified in the turnout structures of the Finnish state rail network and different kinds of solutions for those have been sought. In
cooperation with turnout suppliers, new elastic turnouts have been developed and introduced few years ago, which seek to correct several identified problems.
Experience with new elastic turnouts has been mainly good, although numerous
problems have also emerged. In addition, the development of rail traffic is creating pressure to increase axle weights and speeds in turnouts.

Based on these identified problems and actions taken, the main objective of this
study is to identify which issues would be most critically affected by the potential higher speed and axle weight of new elastic turnouts and which issues should be considered in the design if speeds are increased to 250 km/h. Alongside the development of high-speed turnouts, the long time period effects of under sleeper pads on the stability of track geometry and the benefits of rail lubrication to reduce rail side wear and noise in the diverging route are also investigated. In addition, the report reviews how maintenance values for existing point machines should be developed to reduce false openings of point machines.

The work includes a literature review of the special features of high-speed turnouts structures, component solutions used in other countries, and current legislation, regulations and guidelines in Finland and in EU. In addition, the work determines computationally how much loads the different structural layers of the turnout would be subjected to at these designed high speeds. The effects of under sleeper pads on the stability of track geometry and the effects of lubrication on rail wear and noise have been determined by field measurements on the Ring Rail Line and in Oulu.

The literature review and the calculations show that the current elastic turnout
structure in Finland would withstand loads caused by even higher speeds, as long as a movable crossing is used, which reduces the dynamic impact loads in the crossing area. In addition, high-speed turnouts should always be built far enough away from each other so that they can be tamped and maintained individually.

The results related to under sleeper pads obtained from Ring Rail Line reveals that turnouts equipped be USP retain their geometry in long period slightly better than non-USP turnouts. For this reason, it is important to pay special attention to the very first tamping procedure, because the good geometry achieved there is maintained with the USP-sleepers for a very long time.

The probable cause of false openings of point machines was found to be too broad and asymmetric maintenance values for the point machines. Based on the
observation, it is proposed to change the adjustment values of the point machines so that the current snow clearance is reduced by 1 mm. As a result of this change, the detection rollers of the detection bars become closer to the center of the detection notch and the roller cannot rise out of the notch with a negligible movement.

'Measurements of the cross-sectional profile of the switch blade in Oulu showed
that the strong side wear of the switch blade may in fact be due to excessive
vertical wear of stock rail, which leads to situation where there is actually no
steering at all. Based on this observation, it is straightforward that both the stock rail and the switch blade should always be changed at the same time in order to maintain a sufficient level of rolling radius difference in the switch area.
Translated title of the contributionDevelopment in turnouts
Original languageFinnish
Number of pages104
ISBN (Electronic)978-952-405-085-2
Publication statusPublished - Jun 2023
Publication typeD4 Published development or research report or study

Publication series

NameVäyläviraston julkaisuja
ISSN (Electronic)2490-0745


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