Improved Destressing of Continuous Welded Rail for Better Management of Rail Neutral Temperature

Kish, Andrew; Samavedam, G

doi:10.3141/1916-09

Cited by 3 publications

(4 citation statements)

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“…Train braking, acceleration and temperature gradients along the rail can cause rail longitudinal movement. 16 Creep can occur in critical locations such as near fixed structures (level crossings, turnouts and fixed top bridges), in sags at the bottom of gradients or at any track segment with a history of buckles.…”

Section: Sft Measurement Principles Rail Creep Methodsmentioning

confidence: 99%

Development of a unified railway track stability management tool to enhance track safety

Ahmad

Mandal

Chattopadhyay

et al. 2013

Proceedings of the Institution of Mechanical Engineers, Part F:

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Track buckling is a serious problem for railways. High longitudinal rail stresses contribute to problems such as track buckling, rail joint failure, rail breakage and failure of turnouts. The direct and indirect costs of track buckling problems are very high. The influences of rail temperature, stress-free temperature (SFT) and lateral misalignment of track on track buckling need comprehensive investigation. In this paper, an experimental design comprising strain gauges, thermocouples and rail stress sensors has been implemented on the Queensland Rail heavy haul 60 kg/m rail network. A new creep measurement technique using internal rail stress has been developed. The changes in rail neutral temperature due to the variation of actual rail temperature and the occurrence of rail creep in straight and curved track is quantified. Modes of differences of SFT in the two rails at a location, and of SFT in straight track and in curved track are discussed. The relationship of SFT to rail temperature is also presented. Daily variation in rail temperature due to ambient air temperature is presented. Field trials showed that SFT can vary by 2-3 C during the day. Based on this finding and the derivation of an equation for change of SFT, an improvement in utilising rail creep measurements for assessing track condition has resulted. This finding suggests that it is possible to determine the SFT throughout a day rather than just a single SFT value. This paper also presents a simple track stability management tool that is based on two major parameters, namely rail stress and track resistance. Each parameter in the tool has been given three levels of value to determine the required preventive measures. Overall, the tool decides the need for speed restriction during hot weather based on the quantified parameters from the field trials and rail standards.

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Section: Sft Measurement Principles Rail Creep Methodsmentioning

confidence: 99%

Development of a unified railway track stability management tool to enhance track safety

Ahmad

Mandal

Chattopadhyay

et al. 2013

Proceedings of the Institution of Mechanical Engineers, Part F:

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“…(1, 2). In 2001, Esveld compared the railway temperature in sunny and cloudy weather and then compared it with Hunt's experimental relation [3] (Fig 1). Mr. Chapman predicted the air and rail temperatures using a high-quality thermal camera.…”

Section: Parameters That Important In Variations Of Neutral Temperaturementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Since compressive axial force occurs in the rails at temperatures higher than neutral temperature, in addition to the railway cross-section resistance criterion, lateral stability criterion of track structure should be also considered to prevent track buckling. Thus, in the technical literature, most of the experts believe in considering neutral temperature as follows [4], [3]:T neutral = (T max +T min )/2 + T st where Tst is often positive and selected about 5°C. Previous studies [5],[6] have shown that, in straight tracks, neutral temperature is almost constant and only slightly increases in summer and decreases in winter.…”

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New Definition of Neutral Temperature in Continuous Welded Railway Track Curves

Zakeri

Barati

Mohammadzadeh

2017

Period. Polytech. Civil Eng.

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Keywords neutral temperature, buckling rail tracks, axial rail forces IntroductionBecause of the existence of gap junctions in traditional ballast tracks, they could be longitudinally displaced without any axial forces [1]. In contrast to these tracks, due to the removal of gaps in welded tracks, axial force occurs, which is a function of railway cross-section of rails, modulus of elasticity, thermal expansion coefficient, and temperature variations relative to welding temperature.Railway neutral temperature during railway construction as well as repair and maintenance operations should be selected and controlled so that the minimum compressive force is applied to the track in summer to prevent track buckling and the tensile force in the tracks in winter does not cause any failure nor breaking in tracks [2].When railway gaps are welded (converted into CWR), the welding temperature of tracks is considered neutral temperature, at which there is no axial force. Knowing the railway neutral temperature in railway tracks could not only make it possible to calculate the axial force in the rails, but also help estimate the critical temperature and appropriate temperature for repair and maintenance operations.Selecting appropriate time for welding and thus neutral temperature is of high importance and depends on the maximum and minimum regional temperature. Since compressive axial force occurs in the rails at temperatures higher than neutral temperature, in addition to the railway cross-section resistance criterion, lateral stability criterion of track structure should be also considered to prevent track buckling. Thus, in the technical literature, most of the experts believe in considering neutral temperature as follows [4], [3]:T neutral = (T max +T min )/2 + T st where Tst is often positive and selected about 5°C. Previous studies [5],[6] have shown that, in straight tracks, neutral temperature is almost constant and only slightly increases in summer and decreases in winter. Further, the traffic crossing the track can change neutral temperature. Department of Transportation Federal Railroad Administration (FRA) collected the railway temperature and axial force variations during 9 months on FAST track by installing strain gauges and thermometers.

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The Structure Design of Low Frequency Electromagnetic Induction Heating System Based on Analysis of Thermal Effect

Liu

Wang

et al. 2013

AMM

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The low frequency transverse magnetic electric induction heating system uses high penetration of low frequency electromagnetic induction heat objects, which is new and high efficient. Due to the magnetic fluxing through objects transversely, it is different with other electromagnetic induction heating methods and this makes it applied more widely. And in this paper, we present the application of low frequency transverse magnetic electric induction heating system in the technique of the lock temperature on seamless line. With the analysis of heating efficiency, it also combines the theory of eddy current loss calculation with the verification results of finite element calculation and introduces the structure design of this system then. Keywords: low frequency electromagnetic induction, continuous welded rail, the lock temperature on seamless line, finite element

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Improved Destressing of Continuous Welded Rail for Better Management of Rail Neutral Temperature

Cited by 3 publications

References 0 publications

Development of a unified railway track stability management tool to enhance track safety

Development of a unified railway track stability management tool to enhance track safety

New Definition of Neutral Temperature in Continuous Welded Railway Track Curves

The Structure Design of Low Frequency Electromagnetic Induction Heating System Based on Analysis of Thermal Effect

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