Railway sleeper - Articles and news items
Under Sleeper Pads in Track – the UIC project (Florian Auer, Past Project Manager for ‘USPs in Track’ / Rodolphe Potvin, Head of Track Laboratories, SNCF / Paul Godart, Deputy Director of Infrastructure at Infrabel and Chairman of the UIC Track Expert Group / Laurent Schmitt, Infrastructure Senior Advisor, UIC)
In-service track monitoring (Clive Roberts, Professor of Railway Systems at the University of Birmingham and Director for Railway Research, Birmingham Centre for Railway Research and Education / Paul Weston, Research Fellow, Birmingham Centre for Railway Research and Education)
Issue 4 2012 / 1 August 2012 /
A railway sleeper is the structural element which transversally connects the two rails by means of fastening components, thus ensuring its gauge. Its additional function is to firmly secure the track to the ballast and to distribute the loads transferred from railway carriages to the ballast. One of the most important parameters in the characterisation of performances given by railway sleepers is represented by their lateral resistance to the sliding: the higher its value increases, the better the track stability becomes, thus reducing the frequency of maintenance interventions necessary to keep the superstructure efficient. This article focuses on the performance profile of an innovative railway sleeper, patented in Italy and called ‘EGA’ (High Performance mono-Block sleeper), under different efficiency conditions of the ballast. The research is carried out through a comparative assessment of traditional mono and bi-block sleepers, evaluating the resistance of the single sleeper thought as independent of the other constituents of the track.
The traditional ballasted railway superstructure normally involves the use of reinforced concrete mono or bi-block sleepers. More specifically, a reinforced concrete mono-block sleeper consists of a single concrete element, longitudinally pre-stressed and differently sized according to the railway networks in the various countries. In Italy, for instance, for lines running at a speed less than 200km/h, RFI S.p.A. generally employs a sleeper which is 2.30m-long, with a trapezoidal section and variable dimensions both in height and in width: maximum at the extremity (base width 30cm and height 19cm) and lesser at the centre (20cm and 15cm); the weight can range from 250 to 280kg1. A bi-block sleeper consists of two lightly reinforced concrete elements, held together by a steel tie rod whose function is to guarantee the correct track gauge and to keep the adequate spacing among the aggregates in the casting. Compared to mono-block sleepers, bi-block sleepers have greater resistance to lateral actions and lighter weight.