Derailment Causes and Analysis
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Questions and Answers

What are some probable reasons for derailments categorized as Type-4?

  • Obstructions and disturbed track (correct)
  • Excessive train speed
  • Low thrust and high wheel load
  • Improperly maintained rolling stock

    • What aspect of track parameters is crucial to assess before a derailment?

  • Speed of the train prior to derailment
  • Amount of cargo on the train
  • Readings of track geometry (correct)
  • Type of locomotives in use

    • What is the function of the lock bar in a motor-operated point?

  • To assist in changing the route of the train
  • To detect proper housing of points (correct)
  • To secure the train in place
  • To provide electrical power to the switch

    • Where do most derailments at points and crossings typically originate?

    <p>At the toe of the tongue rail or near the nose of the crossing</p> Signup and view all the answers

    What must be checked when a derailment occurs on a point?

    <p>The gauge of point at several specified locations</p> Signup and view all the answers

    Why is it important to check records of previous maintenance after a derailment?

    <p>To assess work done in the last few days</p> Signup and view all the answers

    What is a potential consequence of rail failure in relation to derailments?

    <p>Increased risk of derailment</p> Signup and view all the answers

    What factor is essential for the operation of points in rail systems?

    <p>Accurate alignment of the rails</p> Signup and view all the answers

    What causes creep in railway tracks primarily?

    <p>Temperature variation causing expansion and contraction of the rail</p> Signup and view all the answers

    According to the IRPWM, what is the maximum amount of creep permitted in tracks?

    <p>150 mm</p> Signup and view all the answers

    What is a significant factor that may lead to buckling in railway tracks?

    <p>Rapid changes in temperature absorbing maximum heat</p> Signup and view all the answers

    What is the primary risk when rail fasteners are unable to hold rails properly?

    <p>Potential derailment of trains</p> Signup and view all the answers

    Which of the following is a defect that can occur in rolling stock?

    <p>Defective brake gear</p> Signup and view all the answers

    What is the maximum allowed slack in gauge at the toe of the turnout?

    <p>6 mm</p> Signup and view all the answers

    What should be ensured about the gauge on adjoining tracks to points and crossings?

    <p>It must match the points and crossings gauge.</p> Signup and view all the answers

    Which aspect should not be checked if a derailment is suspected near the switch?

    <p>Clearance between wing rail and stock rail</p> Signup and view all the answers

    How should the track gauge be adjusted from the points to the adjoining track?

    <p>Brought to the same gauge at a rate of 1 mm in 3 metres.</p> Signup and view all the answers

    What condition of the tongue rail should be examined in case of suspected derailment?

    <p>Thickness</p> Signup and view all the answers

    What is a notable feature of diamond crossings?

    <p>They require critical monitoring due to their structure.</p> Signup and view all the answers

    What is the recommended practice for gauge maintenance over turnouts?

    <p>To maintain uniform gauge.</p> Signup and view all the answers

    What is the recommended minimum depth of ballast for BG Group A?

    <p>300 mm</p> Signup and view all the answers

    Which condition requires recording in interlocked points?

    <p>Slackness between the locking bar slot and slide.</p> Signup and view all the answers

    Which type of rail wear occurs primarily on the top surface and gauge face?

    <p>Vertical wear</p> Signup and view all the answers

    When measuring alignment of a turnout, which interval is recommended?

    <p>1.5 metre intervals</p> Signup and view all the answers

    What should be verified regarding the condition of the nose when derailment is suspected near the crossing?

    <p>Its wear, breakage, or bending.</p> Signup and view all the answers

    What is the lateral wear limit for BG Group A on curves?

    <p>8 mm</p> Signup and view all the answers

    What commonly causes derailments related to sleepers?

    <p>Damage to sleeper structure</p> Signup and view all the answers

    Which ballast factor is NOT mentioned as affecting ballast resistance?

    <p>Weather conditions</p> Signup and view all the answers

    What is the maximum allowable vertical wear for 52 kg/m rail according to IRPWM?

    <p>8 mm</p> Signup and view all the answers

    Which fastener type is used with wooden sleepers?

    <p>Round head spikes</p> Signup and view all the answers

    Which factor relates to the shape of ballast?

    <p>Size of ballast</p> Signup and view all the answers

    What is the lateral wear limit for BG Group C on straight tracks?

    <p>8 mm</p> Signup and view all the answers

    What does a visual inspection of a fractured rail primarily detect?

    <p>Age of the fracture</p> Signup and view all the answers

    What is the maximum allowable twist as per the Railway Board letter?

    <p>3 mm/m</p> Signup and view all the answers

    Which of the following does not cause unevenness in the track?

    <p>Properly packed sleepers</p> Signup and view all the answers

    The formula for calculating versine is given by which of the following equations?

    <p>V = 125.C^2/R</p> Signup and view all the answers

    For a cord length of 3.6 meters, which category does unevenness fall into if measured above 15 mm?

    <p>Category D</p> Signup and view all the answers

    What is the maximum cant allowed on Group D and E routes?

    <p>140 mm</p> Signup and view all the answers

    What measurement must not exceed 20 mm for speeds less than 100 Kmph?

    <p>Versine variation</p> Signup and view all the answers

    What does ballast primarily do in the track structure?

    <p>Maintains track geometry</p> Signup and view all the answers

    Which of the following does not directly relate to the measurement of super elevation?

    <p>Track gauge</p> Signup and view all the answers

    According to IRPWM, the maximum cant deficiency for speeds in excess of 100 Kmph on Group A and B routes is?

    <p>100 mm</p> Signup and view all the answers

    The distance used in calculating twist is measured between which two points?

    <p>A &amp; B</p> Signup and view all the answers

    What is the maximum displacement of track creep allowed according to regulations?

    <p>150 mm</p> Signup and view all the answers

    Which factors are primarily responsible for causing buckling in railway tracks?

    <p>Temperature rise and improper support</p> Signup and view all the answers

    Which of the following is NOT listed as a defect of rolling stock?

    <p>Improperly aligned sleeper</p> Signup and view all the answers

    What type of displacement occurs in a track due to the phenomenon known as creep?

    <p>Longitudinal displacement</p> Signup and view all the answers

    Which section of track is most susceptible to buckling due to temperature changes?

    <p>Bridges and level crossings</p> Signup and view all the answers

    What factor is crucial when examining a derailment with a single flange mark on the rail table?

    <p>The length of the flange mark</p> Signup and view all the answers

    Which situation is most likely to cause a Type-2 derailment?

    <p>Breaking of vehicle suspension arrangement</p> Signup and view all the answers

    When addressing a Type-3 derailment, which factor should be primarily considered after identifying the flange mark?

    <p>Length of the flange mark</p> Signup and view all the answers

    What must be critically examined to determine the cause of a Type-2 derailment?

    <p>Position of the brake power vehicles</p> Signup and view all the answers

    In the event of a derailment, why is the condition of loads in non-derailed vehicles also important?

    <p>It can reveal loading practices that contribute to safety</p> Signup and view all the answers

    What should be done after identifying the first wheel drop mark in a derailment investigation?

    <p>Trace back to ascertain the mount mark</p> Signup and view all the answers

    What does a long flange mark typically indicate about the wheel load during a derailment?

    <p>The wheel load was intermittently light</p> Signup and view all the answers

    Which condition must be checked concerning brake power during an investigation of Type-2 derailments?

    <p>The position of brake power on each vehicle</p> Signup and view all the answers

    What is the maximum allowable twist in railway tracks as per the guidelines?

    <p>3 mm/mt</p> Signup and view all the answers

    In track measurements, what does the term 'unevenness' specifically refer to?

    <p>Forced oscillations in a vehicle caused by track defects</p> Signup and view all the answers

    For curves measured at a speed of 120 Kmph, the variation of versine should not exceed what amount?

    <p>20 mm</p> Signup and view all the answers

    What is the correct formula for calculating super elevation (cant)?

    <p>C = GV2/127R</p> Signup and view all the answers

    Long sags in the track are classified distinctly from unevenness. What best describes this classification?

    <p>Not recorded as unevenness</p> Signup and view all the answers

    What is the recommended minimum depth of ballast for BG Group E?

    <p>150 mm</p> Signup and view all the answers

    For which route classification is the maximum cant specified as 140 mm?

    <p>Group D routes</p> Signup and view all the answers

    What is the term used to describe the difference in longitudinal levels over a fixed base in track measurements?

    <p>Unevenness</p> Signup and view all the answers

    Which type of rail fasteners is used with prestressed concrete sleepers?

    <p>Elastic clips with liners</p> Signup and view all the answers

    What is the key factor in determining the radius of a curve?

    <p>Degree of curvature</p> Signup and view all the answers

    What type of rail wear affects the top surface and gauge face primarily?

    <p>Vertical wear</p> Signup and view all the answers

    What commonly leads to forced oscillations in a vehicle using the railway track?

    <p>Loose packing of sleepers</p> Signup and view all the answers

    According to the specified guidelines, what is the maximum allowable lateral wear for curves on Group C routes?

    <p>8 mm</p> Signup and view all the answers

    What is the maximum allowed cant deficiency for speeds over 100 Kmph on group A and B routes?

    <p>100 mm</p> Signup and view all the answers

    Which parameter is crucial to check when assessing rail conditions after a fracture?

    <p>Nature of the failure</p> Signup and view all the answers

    For a BG 60 kg/meter rail, what is the maximum allowable vertical wear?

    <p>13 mm</p> Signup and view all the answers

    Which factors affect ballast resistance, based on size?

    <p>Material, Shape, State of consolidation</p> Signup and view all the answers

    What is the primary risk associated with damaged sleepers?

    <p>Potential for derailment</p> Signup and view all the answers

    What is the recommended lateral wear limit for BG Group A on straight tracks?

    <p>8 mm</p> Signup and view all the answers

    Which of the following rail types has the highest allowable vertical wear limit?

    <p>60 kg/meter</p> Signup and view all the answers

    What is the maximum permitted slack in the gauge at the toe for housing the tongue rail?

    <p>6 mm</p> Signup and view all the answers

    Which condition must be verified when examining the tongue rail for a suspected derailment?

    <p>Height of the tip of the switch</p> Signup and view all the answers

    What is recommended to be done to the gauge on adjoining tracks if it differs from points and crossings?

    <p>Adjust it to match points and crossings at a specific rate</p> Signup and view all the answers

    In the context of a suspected derailment near the crossing, which factor should NOT be inspected?

    <p>Thickness of the guard rail</p> Signup and view all the answers

    Which of the following statements about maintenance of gauge in turnouts is true?

    <p>It is essential to maintain uniform gauge across all rail sections</p> Signup and view all the answers

    What specific check is required for interlocked points during an inspection?

    <p>Slackness between the locking bar slot and slide</p> Signup and view all the answers

    Which of the following describes a requirement for inspecting diamond crossings?

    <p>Critical watch is needed due to potential structural issues</p> Signup and view all the answers

    During a derailment investigation, what should be examined regarding the condition of the nose at crossings?

    <p>Level of wear including breakage and bent structure</p> Signup and view all the answers

    What is the recommended practice for the alignment check of a turnout?

    <p>Employ a 6 metre chord at 1.5 metre intervals</p> Signup and view all the answers

    What is a significant characteristic of a simple diamond crossing?

    <p>Has two noses with acute angles and two with obtuse angles</p> Signup and view all the answers

    Study Notes

    Derailment Causes and Analysis

    • Type 4 Derailment: Characterized by multiple wheels derailing with flange marks on the rail table.
      • Possible Causes: Obstructions, disturbed track conditions (sabotage or work in progress), rail failure, significant track defects (twist, misalignment, or formation failure), track buckling.
      • Emphasis on Track Parameters: Careful recording of track parameters is crucial when no obvious cause is present.
      • Track Geometry Readings: Vital for understanding vehicle behavior before the derailment.
      • Maintenance Records: Review of previous maintenance activities (rail renewal, stress relief) is essential to assess recent track work.

    Derailments at Points and Crossings

    • Points and Crossings - Vulnerable Points: Points or switches are designed for changing track direction, introducing discontinuities that can weaken track structure.
    • Components of Point System:
      • Tongue Rails: Connected by stretcher bars, hinged to heel blocks.
      • Switch: The assembly of tongue rails and stretcher bars.
      • Pull Rod: Used to operate the switch.
      • Motorized Switch: Modern points are often motorized, featuring interlocking arrangements, lock bars, and detection devices for proper housing.
    • Common Derailment Locations: Most derailments at points and crossings occur at the toe of the tongue rail or near the nose of the crossing.
    • Inspection Checklist for Derailments at Points:
      • Gauge Check: Performed at four locations:
        • 305 mm ahead of the nose of the tongue rail.
        • 152 mm inside the tongue rail for both straight road and turnout.
        • At the heel for the tongue rail for both straight road and turnout.
        • At the middle of the tongue rail for both straight road and turnout.
      • Acceptable Gauge Variation: The gauge should be correct at all locations except the toe, where a 6 mm slack is allowed for housing the tongue rail.
        • IRPWM (Indian Railway Permanent Way Manual) - Para 237(8)(a) and (b): Emphasizes maintaining uniform gauge throughout turnouts.
      • Gauge Adjustment Procedure:
        • Wider or tighter gauge adjacent to points and crossings should be adjusted to match the gauge of the points and crossings.
        • The adjustment should be gradual, with a 1 mm change per 3 meters until the required gauge is achieved.
        • The correct gauge should be maintained for at least one rail length on either side of the point and crossings.
    • Additional Points to Examine in Derailment Suspected Near the Switch:
      • Condition of the tongue rail (broken, chipped, bent).
      • Damage to stretcher bars.
      • Height of the switch tip relative to the stock rail.
      • Thickness of the tongue rail.
      • Gaps between the tongue rail and stock rail.
      • Slackness between the locking bar slot and slide in interlocked points.
      • Condition of brackets supporting the stock rail.
      • Whether the switch jumps when a wheel passes over its heel.
    • Inspection Checklist for Derailments Suspected Near the Nose of Crossing:
      • Condition of the nose (wear, breakage, chips, bends).
      • Reduction in the nose’s level compared to wing rails.
      • Clearances between wing rail and stock rail near the nose (both sides).
      • Clearance between guard rail and stock rail.
      • Alignment of turnout to be measured for smoothness (using a 6-meter chord at 1.5-meter intervals).
    • IRPWM - Comprehensive Check-list: Provides a detailed examination guide for points and crossings.
    • Diamond Crossing: A potentially hazardous structure generally avoided on main lines.
      • Diamond Crossing Components: Four noses with two acute angles and two obtuse angles.
      • Critical Monitoring Required: These components require careful monitoring.
    • Twist: Calculated in mm/meters using the formula:
      • (Algebraic difference in cross-level at two points A & B in mm) / (Distance between points A & B in meters).
        • IRPWM - Para 316(2)(C): Specifies a maximum twist limit of 3 mm/meter based on Railway Board letter no. 631W6/TK/I0/Dt 10.11.1964.

    Track Defects Leading to Derailment

    • Unevenness: Not reflected in gauge or cross-level readings.
      • Causes: Low joints, high joints, loose packing, problems with sleepers, lifting of sleepers.
      • Exclusion: Long sags are not considered unevenness.
      • Measurement: Recorded separately for left and right rails.
      • Method: Difference in longitudinal levels over a fixed base.
      • Impact: Can cause forced oscillations in vehicles, leading to variations in instantaneous wheel load and lateral thrust.
      • IRPWM - Para 607: Classifies unevenness (measured on a 3.6-meter chord) above 15 mm as category D.

    Track Geometry Parameters

    • Versine and Super Elevation: Used to ensure proper curve geometry.
      • Versine Calculation: V = (125 * C^2) / R
        • V: Versine
        • C: Cord length in meters
        • R: Radius in meters
      • IRPWM - Para 421(b)(i): Specifies station-to-station versine variation limits:
        • Speed over 100 kmph: Variation should not exceed 15 mm for stations 10 meters apart.
        • Speed 100 kmph or less: Variation should not exceed 20 mm or 200/1000 of the average versine of the circular section, whichever is greater.
    • Super Elevation Calculation: C = (G * V^2) / (127 * R)
      • C: Cant/Super elevation in mm.
      • G: Dynamic gauge in mm.
      • V: Speed in kmph.
      • R: Radius in meters.
    • IRPWM - Para 406(d): Specifies maximum cant limits:
      • Group A, B, and C routes: 165 mm.
      • Group D and E routes: 140 mm.
    • Cant Deficiency Limits:
      • Speeds exceeding 100 kmph on Group A and B routes: 100 mm (with permission from Chief Engineer for nominated rolling stock and routes).
      • Broad Gauge Routes not covered above: 75 mm.

    Track Structure Components

    • Ballast: Crucial component for track geometry maintenance.
      • Factors Affecting Ballast Resistance: Ballast size, material, shape, consolidation state, sleeper type, and formation cushion.
      • Minimum Ballast Depth: Recommended by IRPWM - Para 263(2):
        • Group A: 300 mm
        • Groups B & C: 250 mm
        • Group D: 200 mm
        • Group E: 150 mm

    Rail Defects

    • Rail Fracture: Accidents caused by rail fracture require investigation to determine the cause.
      • Visual Inspection: Helps determine if the fracture is new or old.
    • Rail Wear:
      • Types: Vertical, lateral, angular
      • Observed Primarily: Top surface and gauge face.
      • IRPWM - Para 302(b): Specifies rail wear limits:
        • Vertical Wear:
          • 60 kg/meter: 13 mm
          • 52 kg/meter: 8 mm
          • 90R: 5 mm
        • Lateral Wear:
          • Curves:
            • Group A & B routes: 8 mm
            • Group C & D routes: 10 mm
          • Straight:
            • Group A & B routes: 6 mm
            • Group C & D routes: 8 mm

    Sleeper Defects

    • Impact of Sleeper Damage: Can cause derailment.
    • Inspection Focus: Ensure thorough inspection of sleepers, particularly those near the point of derailment.

    Rail Fasteners

    • Variations: Specific fasteners for different sleeper types.
      • Wooden Sleepers: Dog spikes, round head spikes, steel keys
      • Steel Trough Sleepers: Steel keys
      • Prestressed Concrete Sleepers: Elastic clips with liners.
    • Inspection: Record the condition of all fasteners during track reading.

    Creep

    • Silent but Dangerous: Longitudinal displacement of track.
    • Causes:
      • Temperature variations (expansion/contraction of rail).
      • Tractive forces from locomotives pushing the rail backward.
      • Braking forces pushing the rail forward.
    • Factors Aggravating Creep:
      • Insufficiently secure rail fasteners.
      • Damaged or inadequate rail seats on sleepers.
      • Poor track joints without proper expansion gaps.
    • IRPWM - Para 242(6): Maximum permitted creep is 150 mm.
    • Creep Indication Points: Provided at 50 and 100 meters from Switch Expansion Joints (SEJ) for long welded rails (LWR) and continuous welded rails (CWR).

    Buckling

    • Track Disruption: A section of track leaves its place and moves sideways.
    • Causes:
      • Rise in temperature.
      • Similar factors to creep.
    • Occurrence:
      • Often happens in the afternoon, when the track has absorbed maximum heat.
      • Frequently near bridges, level crossings, and other areas where the track is firmly anchored.
    • Types: Horizontal or vertical.

    Rolling Stock Defects

    • Wheels and Axles: Broken or hanging fittings.
    • Bolster and Assemblies: Defects.
    • Spring Gear, Axle Guard, and Trolley: Defects.
    • Brake Gear: Defects.
    • Excessive Clearance: Side bearers, pivots, etc.
    • Hot Box/Roller Bearing Failure: Hot bearing.
    • Underframe and Components: Misalignment.
    • Poor Brake Power: Ineffective braking.
    • Tank Wagons (Empty/Unloaded): Broken or disengaged baffle plates.
    • Draw Gear, CBC Gear, and Buffing Gear: Defects.
    • Train Parting and Subsequent Collision: Couplets opening automatically.

    Locomotive Defects

    • Similar to rolling stock defects.

    Derailment Causes and Investigation

    • Type 1 Derailment: Significant derailment, characterized by distinct flange marks on the rail table. Investigation typically involves scrutinizing the rail table, including the flange marks' length and location, to pinpoint the initial point of derailment.

    • Type 2 Derailment: Derailment without visible flange marks on the rail table. Investigation focuses on identifying potential obstructions in the wheel's path, examining the vehicle's suspension system for damage, and inspecting the wheels for jamming caused by bearing failure.

    • Type 3 Derailment: Derailment with a single flange mark on the rail table. This type requires in-depth analysis of the track, rolling stock, loading conditions, and train operations.

      • A long flange mark indicates a prolonged period of reduced wheel load.
      • A short flange mark points to a significant increase in lateral thrust.
      • The weight of the vehicle and the train's speed at the time of the accident influence the flange mark's impression on the rail.

    • Track Defects

      • Gauge: Track gauge must be correct except at the toe, where a 6mm slack is permitted near the switch.

      • Turnouts:

        • Uniform gauge over turnouts is preferred.
        • If track gauge is wider/tighter than the turnout's gauge, adjustment towards a uniform gauge is necessary, tapering over 3 meters.
        • At least one rail length on either side of the turnout must maintain the same gauge as the points and crossings.

      • Switch: In a derailment suspected to have originated near a turnout's switch, carefully assess:

        • The tongue rail's condition (broken, chipped, bent).
        • The age of any damage.
        • The switch tip’s height from the stock rail.
        • The thickness of the tongue rail.
        • Any gaps between the tongue rail and stock rail.
        • Any damage to the stretcher bar.
        • The slackness between the locking bar slot and slide (for interlocked points).
        • The condition of the brackets holding the stock rail.
        • Whether the switch jumps upward when a wheel rolls over its heel.

      • Crossing: In suspected derailments near a crossing, inspect these elements:

        • Condition of the nose (wear, breakage, chipping, bending).
        • Nose level compared to wing rails.
        • Clearance between wing rails and stock rail (near the nose) on both sides.
        • Clearance between guard rail and stock rail.
        • Turnout alignment to check smoothness.

      • Diamond Crossing: Requires close monitoring due to its potentially dangerous structure with four noses.

      • Twist: Is calculated as the algebraic difference in cross level at two points A & B in mm divided by the distance between points A & B in meters. The limit is 3 mm/mt per Railway Board letter no. 631W6/TK/I0/Dt 10.11.1964.

      • Unevenness: Not reflected in gauge and cross level readings. Low joints, high joints, loose packing, sleepers, and sleeper lifting can cause unevenness. Measured as the difference in longitudinal levels over a fixed base, contributing to forced oscillations in a vehicle and potential variations in instantaneous wheel load and lateral thrust. Unevenness above 15111m (on a 3.6m cord) falls under category D (per IRPWM 607).

      • Versine & Super Elevation: Measured to verify curve correctness. Radius of any curve is calculated by dividing 1750 meters by its degree.

        • Versine = (125 x C2) /R where R is the radius in meters, C is the cord length in meters, and V is the verisne.
        • Station-to-station variation of versine over 10 meters should not exceed 15 mm for speeds exceeding 100 Kmph, and 20 mm or 200/0 of the average versine (whichever is greater) for speeds 100 Kmph and below.
        • Super elevation (C) = (GV2) / (127R) where G is the dynamic gauge in mm, V is the speed in Kmph, and R is the radius in meters.
        • Maximum cant (super elevation) is 165 mm on group A, B, and C routes, and 140 mm on group D and E routes.
        • Para 406(2) outlines the maximum cant deficiency:
          • For speeds exceeding 100 Kmph on group A and B routes for nominated rolling stock and routes with permission of Chief Engineer - 100 mm.
          • For broad gauge routes not covered above - 75 mm.

      • Ballast: Essential component in the track structure. Factors influencing ballast resistance:

        • Size, material, shape, state of consolidation, type of sleeper, cushion at formation.
        • Recommended minimum depth of ballast below the sleeper's bottom at the rail seat:
          • Group A - 300 mm.
          • Group B & C - 250 mm.
          • Group D - 200 mm.
          • Group E - 150 mm.

      • Rail: Fracture analysis must be conducted on rails involved in derailments attributed to fracture. Visual inspection can determine if the fracture is recent or indicates an older flaw. For other derailments, the rail's wear is evaluated. Rail wear can be vertical, lateral, or angular.

        • Wear Limits:

          • Vertical Wear:

            • 13 mm for 60 kg/meter (BG)
            • 8 mm for 52 kg/meter
            • 5 mm for 90R

          • Lateral Wear:

            • Curves, Group A & B routes - 8 mm
            • Curves, Group C & D routes - 10 mm
            • Straight, Group A & B routes - 6 mm
            • Straight, Group C & D routes - 8 mm

      • Sleepers: Damage or loss of sleepers can cause derailments. Investigate the condition of sleepers near the point of derailment during gauge and level readings.

      • Rail Fasteners: Differ based on sleeper type.

        • Wooden sleepers: Dog spikes, round head spikes, steel keys.
        • Steel trough sleepers: Steel keys.
        • Prestressed concrete sleepers: Elastic clips with liners between the rail foot and clip.

      • Creep: Silent but dangerous track phenomenon. Longitudinal track displacement caused by:

        • Temperature variation.

        • Locomotive tractive forces.

        • Train braking forces.

        • Creep is exacerbated by faulty rail fasteners, damaged sleepers, and poorly-maintained track joints.

        • Maximum permitted creep is 150 mm (per IRPWM 242(6)).

      • Buckling: One or two rail lengths leave their position and shift sideways. Occurs due to temperature rise and similar causes as creep. May be horizontal or vertical. Most frequent during the second half of the day when the track has absorbed maximum heat, and near bridges and level crossings where the track is firmly anchored.

    Rolling Stock Defects

    • Wheel and Axle: Broken and hanging fittings.

    • Bolster and Assemblies: Defects.

    • Spring Gear, Axle Guard, and Trolley: Defects.

    • Brake Gear: Defects.

    • Excessive Clearance: In side bearers, pivot, etc.

    • Hot Box/Roller Bearing Failure

    • Under Frame and Under Frame Members: Out of alignment.

    • Poor Brake Power

    • Broken or Disengaged Baffle Plates: In empty or unloaded tank wagons.

    • Defective Draw Gear, CBC Gear, and Buffing Gear: Train parting and subsequent collisions.

    • Locomotives: Defects are similar to those found in rolling stock.

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    Description

    Test your knowledge on the causes and analysis of derailments, specifically focusing on Type 4 derailments and factors at points and crossings. Understand the significance of track parameters and maintenance records in preventing derailments.

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