Скачать или смотреть Chapter 9: Maintenance Criteria | Part 3-Defects in Rail | Railway Engineering in Urdu/Hindi

In chapter 9, we will study maintenance criteria of railways system. This chapter is divided into different parts. In this video, we will learn about different types of defects in rails. This is a Full Master's Course on Railway Engineering in Urdu/Hindi.

Railhead wear
Homogeneous lack of matter along internal side of railhead in comparison with nominal theoretical rail profile
Along 45°inclined straight line linking transition radius between side and upper surface of railhead (45°wear)
14 mm under running surface (lateral wear)

Track gauge defects
Displacement of rail from exact planimetry position
14 mm under running surface between internal sides of railheads

Track alignment defects
Displacement of both rails from exact planimetry position
14 mm under running surface between corresponding sides of railheads as average deviation of the consecutive positions defined by fixed wave length ranges (3÷25 m and 25÷70 m)

Track level defects
Displacement of both rails from exact altimetry position
Distance between average rolling surface level in consecutive positions defined by fixed wave length ranges (3÷25 m e 25÷70 m)

Track distortion

Reciprocal displacement of rails from exact altimetry position (potentially dangerous as primary cause of derailments)
‰ rate between transversal level differences in two track sections at fixed distance (distortion measurement basis) and the standard level

Other defects
Lack of track stability
Subsidence of sleepers’ support and underlying ballast Lack of track elasticity
Excessive rigidity of sleepers’ support and underlying ballast
Un-regulation of track expansion gaps
Extension or reduction of thermic gaps at un-welded joints along sections Un-regulation of distance between sleepers
Due to frequent accelerations and decelerations
Sleepers degradation
Progressive subsidence: 1) at fastenings, 2) whole body, particularly for wooden sleepers
Ballast contamination
Progressive modification of original dimension of rocks due to fragmentation and intrusion of powders
Loosening of fastenings

Defects evolution and preventive maintenance
Monitoring activities to identify Alert Levels for critical defects
Maintenance activities required according to detected defect evolution to prevent operational restrictions
Geometrical standards
Target values (after renewal)
Optimal conditions
First quality level
Not requiring correcting interventions on superstructure geometry
Second quality level
Normal operation, degrading causes investigated. planning of maintenance works
Third quality level
Operation without restrictions, urgent maintenance works to be performed Alarm level (relevant degrade)
Operational constraints (speed restriction / traffic interdiction)

Alarm levels for geometrical standards

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