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Rails are one of the main elements of the upper structure of the railway track. The safety and smoothness of the movement of mobile units depends on their reliable operation. During operation, various defects and damages occur in the rails that can directly threaten the safety of traffic. These defects and damages have different causes and development mechanisms, which depend on many operational factors. Studying the causes of the appearance and development of defects in rails is one of the main tasks to increase the uptime of the railway. The rail side wear continues to be one of the basic reasons for removing rails from the rail track. Earlier studies have demonstrated an apparent effect of unbalanced acceleration, rail track parameters and geometrical irregularities (including bond ones) on rail wear. Mostly, the process is typical for small-radius curves the total length of which in Ukrainian railway network is rather great. The article presents the findings of numerical research into vehicle/track interaction under such operational conditions with consideration of existing and prospective structures of rail fastenings. The authors have concluded that train driving modes and rail foundation structure influence the rate of rail head side wear in small-radius curves on the rail track.

Since 2003 Ukrainian railways have used KPP-5 intermediate elastic fastenings. These fastenings unlike their predecessors (for example, terminal-bolted fastenings (KB) widely used on railways), first of all, have fewer elements. The KPP-5 fastening does not include screw joints, which considerably increases the pressing force between rail and tie, and resistance to track displacement forces. This may lead to reduction of the total labour input for routine track maintenance due to cutback of track works needed for mounting terminal and insert bolts. The article deals with forecasting the operational life of PRP 3.2 (9mm depth) and PRP 3.2.1 pads (10mm depth). In engineering the operational life is a time interval (for the railway track – tonnage passed) during which the element fulfils its functions. One of the main reasons why the assembly unit KPP-5 fails is low pressing forces between rail and tie. It occurs due to many processes; among the basic ones is the changed characteristic of underrail pads. And the application of new types of pads – PRP 3.2 (9mm) and PRP 3.2.1. (10mm) may solve this problem.

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