Comparison of structural design methods for railway composites and plastic sleepers and bearers

Abstract

Railway sleepers are safety-critical and essential components in a ballasted railway track system. Sleepers could principally be made of different materials, such as, timber, steel, concrete, composite and plastic. The deterioration process of sleepers depends largely on the materials of which they are made. The most popular material for manufacturing sleepers nowadays is concrete. In very recent years, a new type of railway sleeper has been developed using composite and plastic materials. These plastic sleepers have been trialled as bridge transoms and, to a limited extent, as switch and crossing bearers. A limited application of composite (a combination of cement, steel and plastics) to bridge transoms can also be seen. At present, there is no unified design method or standard for these new plastic and composite sleepers and bearers. The lack of design information can compromise public safety. This paper thus highlights the design aspects for plastic and composite sleepers in comparison with traditional materials. It reveals that limit states design concept is the most optimal approach for sleeper design and manufacture. The insight will help rail asset owners and managers establish predictive and condition-based track design and maintenance.

The Effect of Unsupported Sleepers/Bearers on Dynamic Phenomena of a Railway Turnout System under Impact Loads

“…Moreover, the bending moment difference for the unsupported longest bearer seems to be inconsequential, which could be seen from Figure 28e. Maximum positive and negative bending moments for the selected point are In general, the graphs in Figure 29 show similar behavior in fully supported bearer case [12,[28][29][30][31]. Symmetrical distribution in some bearers, such as bearers at normal track section or asymmetrical distributions in some bearers such as bearers at closure panel, could be observed.…”

Effect of Extreme Climate on Topology of Railway Prestressed Concrete Sleepers

“…The main objective of this study is to address the time-dependent behaviour of railway prestressed concrete sleepers under extreme climatic conditions. Climatic effects on prestressed concrete sleepers are very important [21]. Changing environmental factors will significantly influence the performance of prestressed concrete sleepers.…”

Damage and failure modes of railway prestressed concrete sleepers with holes/web openings subject to impact loading conditions

“…It should be noted that railway sleepers are a structural and safety-critical component in railway track systems experiencing aggressive dynamic conditions [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. Railway sleepers can be constructed of various materials such as timber, concrete, steel, and other engineered materials [16][17][18]. It is important to note that an individual failure of a sleeper will generally not cause disruption to rail operations but it will increase periodic track maintenance costs, increase costs and effort for safety-related track inspection and monitoring, and impair ride comfort of train passengers depending on the severity.…”

“…It is important to note that an individual failure of a sleeper will generally not cause disruption to rail operations but it will increase periodic track maintenance costs, increase costs and effort for safety-related track inspection and monitoring, and impair ride comfort of train passengers depending on the severity. For various exceptional cases, the failure of a sleeper will significantly increase the risk of rail breaks at welds, joints, rail surface defects, rail foot defects, turnouts (or called 'switches and crossings') [17][18], and will inevitably create asymmetrical load balancing and redistribution [11]. These exceptional risks can lead to detrimental train derailments causing not only financial penalties but also losses of lives [14][15].…”