The Swiss experience on the wear of railway switches & crossings
Using databases of the Swiss Federal Railways (SBB CFF FFS), statistical analyses are carried out on the expected lifetime of railway switches (points) & crossings and their respective components. The expected lifetimes are attributed to different parameters which influence the speed of degradation or wear, e.g. total train loads (expressed in cumulative tonnages), axle loads, train type, the quality of the foundation or the quality of initial installation. First results confirm long known basic knowledge, e.g. an increase in the average replacement age due to better components and changing maintenance politics. At the same time unexpected results are found. Examples of this are the not statistically confirmed reduced lifetime of a switch being placed in a curve, or the complete irrelevance of the switch angle on their expected life duration, although a shorter life with larger angles would be expected due to higher dynamic lateral loads. Some explanations for these unexpected results are given and are probably related to both the situation in the field and non technical maintenance politics. With this knowledge on degradation, a model is composed which is used to forecast maintenance and renewal needs of switches, crossings and their components. To test the model, an old asset database with switches and crossings is used, and the results of the model (proposed replacements including the time of replacement) is compared with the actually carried out works.