Railway Engineering Chapter 4: Permanent Way

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Questions and Answers

What is the most serious effect of rail creep?

Increased maintenance costs

Buckling of the track (correct)

Uneven train speed

Discomfort for passengers

Which of the following conditions can help reduce the creep of the track?

Increased stiffness of the track (correct)

Using uniform ballast

Loose fittings of rails

Poor quality sleepers

What causes the creep of rails during hot summer weather?

Expansion and contraction of rails (correct)

Uneven spacing of the sleepers

The weight of the rails

Improper alignment of curves

Which factor contributes to unbalanced traffic and hence rail creep?

Heavy traffic in one direction Signup and view all the answers

Which of the following is NOT a factor affecting rail creep?

Humidity in the atmosphere Signup and view all the answers

What are the four main components of the track structure?

Formation, Ballast, Sleepers and fastenings, Rails Signup and view all the answers

Which of the following is NOT a purpose of the formation?

Absorbs noise and vibrations Signup and view all the answers

What is the consequence of inadequate care in maintaining the formation?

Derailments due to disturbance of track geometry Signup and view all the answers

Which factor is NOT mentioned as affecting the formation?

Type of ballast used Signup and view all the answers

Which aspect of track needs to be checked regularly to avoid formation failure?

Geometry of track and supports Signup and view all the answers

What role does ballast play in the track geometry?

Distributes load and absorbs shocks and vibrations Signup and view all the answers

What action should be taken to avoid sinking of the track during diversions?

Preventive measures in new formations during rains Signup and view all the answers

What is the maximum allowable cross level difference during maintenance according to the tolerances set by the Railway Board?

4 mm Signup and view all the answers

How is the twist calculated between two stations that are 3 meters apart?

By adding the height differences and dividing by 3 Signup and view all the answers

If the left rail at station No. 1 is higher by 10 mm and the right rail at station No. 2 is higher by 8 mm, what is the twist measured?

6 mm per meter Signup and view all the answers

What role does twist play in the context of derailment?

It causes uneven loading of wheels. Signup and view all the answers

What is the maximum allowable twist on a 4-meter wheel base considered in derailment analysis?

6 mm Signup and view all the answers

What is the term used to describe the longitudinal movement of rails in the track?

Creep Signup and view all the answers

Which factor is NOT mentioned as affecting the wave motion in the track?

Temperature fluctuations Signup and view all the answers

If one rail at station No. 1 is 12 mm higher and at station No. 2 is 6 mm higher, what would be the effective twist?

2 mm per meter Signup and view all the answers

What could happen if the left rail is higher at station No. 1 and the right rail is higher at station No. 2?

Derailment risk increases Signup and view all the answers

According to the wave theory, what happens to the rails when a moving train passes over them?

They deform and then revert to original shape. Signup and view all the answers

How much creep can occur in the rails per month, according to the information provided?

A few centimeters Signup and view all the answers

During maintenance, what is the maximum allowable twist variation over a 3-meter span?

2 mm per meter Signup and view all the answers

In analyzing derailment, from where should twist be measured?

On the wheel base of the vehicle that derailed first Signup and view all the answers

Which of the following theories explains the cause of rail creep as per the content?

Wave Theory Signup and view all the answers

What happens to the raised portion of the rail at the rear of the moving wheel?

It assumes its normal position. Signup and view all the answers

Which factor does NOT affect the pitch and depth of the wave formed in the track?

Economic conditions Signup and view all the answers

The openings in rail joints become wider due to which phenomenon?

Creep Signup and view all the answers

What role do the moving wheels of the train play in the process of creep?

They cause wave motion along the rail. Signup and view all the answers

Which of the following is an impact of the wave motion caused by a moving train?

Displacement of rail joints Signup and view all the answers

What is the highest value of effective twist on a 4 meter wheel base between specific stations?

Between station 0 and station 4 Signup and view all the answers

Which track category corresponds to a permissible twist of 5 to 7.5 mm/metre for B.G. trains?

B Signup and view all the answers

What is the permissible alignment measurement for B.G. track in the context of track alignment?

3 mm Signup and view all the answers

What could potentially cause dangerous oscillations in a vehicle on the track?

Coinciding natural and exciting frequencies Signup and view all the answers

Which chord should be used for lateral alignment in the assessment of track irregularities?

7.2 metre chord Signup and view all the answers

For B.G. and M.G., what is the maximum allowable unevenness in track alignment?

2 mm Signup and view all the answers

Which track category allows a twist of 7.5 to 10 mm/metre for B.G. trains?

C Signup and view all the answers

What is the significance of flanges in railway systems?

They guide the wheels on the rail Signup and view all the answers

Identify the effective twist value between station 1 and station 3.

-7 Signup and view all the answers

What condition leads to flanges contacting the rail?

Poor alignment Signup and view all the answers

What is a potential effect on rail joints due to the accumulation of creep?

Creep can cause the rail joint to jam, preventing expansion. Signup and view all the answers

Which method is used to measure rail creep in the track?

Fixing posts and measuring the distance to marked locations. Signup and view all the answers

Which of the following remedial steps can help mitigate excessive creep in rails?

Using anti-creepers or anchors to secure the rails. Signup and view all the answers

What is the maximum permissible limit of creep in rail systems as mentioned?

150 mm Signup and view all the answers

What condition can result from inadequate maintenance of rail joints?

Elevated risk of impact force from moving wheels. Signup and view all the answers

What is referred to as cushion ballast?

Ballast depth below the bottom of the sleeper. Signup and view all the answers

Which factor does NOT affect ballast resistance?

Type of track gauge Signup and view all the answers

What defines crib ballast?

Ballast provided between the sleepers. Signup and view all the answers

What is the purpose of sleepers and fastenings in a railway track?

To hold the rails within gauge limits and transmit load. Signup and view all the answers

What is NOT a recommended ballast size for railway tracks?

25 mm Signup and view all the answers

What is shoulder ballast specifically designated for?

To extend beyond the edge of the sleeper. Signup and view all the answers

What enhances friction at the flange contact area during running?

Smeared ballast on the gauge face of the rail. Signup and view all the answers

What is the primary effect of slack gauge on rail systems?

Increased lateral oscillations and potential wheel drop Signup and view all the answers

Which of the following is a consequence of tight gauge?

Excessive flange forces and wheel lift Signup and view all the answers

Which condition could indicate gauge distortion?

Damaged and loose fastenings in the track Signup and view all the answers

If an abnormal derailment cause is suspected, how many stations should be marked?

30 stations covering a distance of 90 meters Signup and view all the answers

What happens to the wheel flange due to extreme tight gauge conditions?

It starts to grind against the rail edge Signup and view all the answers

What is indicated by a wheel dropping off the track?

There is excessive slackness in the gauge Signup and view all the answers

What should be the first step when taking track measurements post-derailment?

Ascertain the point of mount or drop Signup and view all the answers

Which situation can be a result of neglected fastening in railway tracks?

Increased gauge distortion Signup and view all the answers

What primarily increases the risk of track distortion during high-speed operation?

Loose fastenings due to vibrations Signup and view all the answers

What is the permissible cross level deficiency under normal conditions?

75 mm Signup and view all the answers

Which measuring device is used for simultaneously recording gauge and cross levels?

Modified RDSO gauge Signup and view all the answers

What action should be taken to ensure the accuracy of the spirit level before use?

Check bubble sensitivity Signup and view all the answers

In the context of derailment, how should cross levels be recorded?

Taking the left rail as the reference Signup and view all the answers

What is considered a limiting value for cross level variations at stations 3 meters apart?

13 mm Signup and view all the answers

What potential issue arises from excessive twist in rail track?

Floating of one wheel Signup and view all the answers

When measuring cross levels, what does it indicate if the spirit level moves 10 mm to the right?

Right rail is lower by 10 mm Signup and view all the answers

What is the effect of frequent variations in cross levels referred to as?

Twist Signup and view all the answers

What is a common consequence of neglecting cross level measurements?

Higher risk of derailments Signup and view all the answers

How are cross levels measured from the points of mount or drop?

45 meters on either side Signup and view all the answers

What is the permissible twist range for Category B track?

5 to 7.5 mm/metre Signup and view all the answers

What does a significant difference between the natural frequency of the vehicle and the exciting frequency lead to?

Potential derailment Signup and view all the answers

Which measure is taken to maintain track alignment and unevenness tolerances?

7.2 metre chord for lateral alignment Signup and view all the answers

Which condition can lead to flanges contacting the rail during track irregularities?

Inadequate spring oscillation. Signup and view all the answers

How is effective twist calculated between any two stations?

By finding the difference in height between the left and right rails. Signup and view all the answers

What is the effective twist calculated between Station 0 and Station 4?

11 mm Signup and view all the answers

For a vehicle to be in a safe operational state, what should be the condition of the track?

Well aligned to avoid any irregular contact. Signup and view all the answers

What can occur if the oscillations of springs on a vehicle exceed safe limits?

Lead to derailment. Signup and view all the answers

What is the primary purpose of maintaining service tolerances for track alignment and unevenness?

To prevent derailment and ensure passenger comfort. Signup and view all the answers

Study Notes

Chapter 4: Permanent Way

Track structure comprises four main components: formation, ballast, sleepers and fastenings, and rails.
These components require regular and periodic checks by Assistant Engineers (IRPWM para 107), PWI (IRPWM para 123, 124 & 139), and P.Way Mistries, Mates, and Keymen (IRPWM Part 'C').

4.1 Formation

Railway track is laid on a formation prepared on soil.
Formation strength depends on soil type (sandy, loam, clay, etc.).
Formation purpose: distributes train, track, and ballast weight over a wider natural ground area, facilitates good drainage, and provides a smooth and regular surface for ballast and track laying.
Formation is affected by factors including sudden embankment subsidence, base failure, ballast puncturing due to heavy rains, and muddiness.
Formation problems can lead to track geometry disturbance and derailment risks.

4.2 Ballast

In track geometry, ballast plays a key role; absorbing noise, shocks, vibrations and distributing loads from wheels to the formation.
Ballast ensures lateral and longitudinal track stability.
Insufficient ballast can result in track distortion or buckling.
Recommended ballast size is 50mm. Profiles and minimum depths are detailed in IRPWM Para. 263.
Types of ballast: Cushion Ballast and Crib Ballast (figures show these).
Shoulder ballast is placed beyond the sleeper edge.

4.2.2 Ballast Resistance

Ballast's ability to absorb shocks is influenced by: ballast material, size, shape of ballast particles, ballast profile, state of consolidation, and type of sleeper.

4.3 Sleepers and Fastenings

Sleepers and fastenings maintain the rails at the desired gauge.
Failure in sleepers and fastenings can disrupt track geometry and cause rail shifting.
Key functions of sleepers and fastenings: holding rails within gauge limits, transmitting load from rail to ballast, supporting resilient frequency vibrations, providing lateral and longitudinal track strength, accommodating track geometry rectification, and resistance to rail longitudinal creep.
Sleepers can be wooden, CST 9 cast iron, steel trough, or concrete.
Various fastenings include bearing plates, fish plates, screws, spikes, steel keys, cotters, and Pandrol clips.
Sleeper density and condition should meet IRPWM guidelines (e.g., Para. 244 (4)).

4.4 Rails

Rail wear plays a critical role in mounting tendency and potential derailment risk.
Types of rail wear: vertical, lateral, and angular.
Permissible limits for rail wear are defined in IRPWM Para 302 iii & iv (figures show measurement).

4.5 Gauge

Gauge refers to the distance between the outer edges of the two rails.
Standard gauge is 1676 mm on Broad Gauge (B.G.).
Gauge irregularity leads to sinusoidal oscillations of the vehicle and potential wheel flange attacks.
Conditions like tight gauge and slack gauge affect track stability and may cause derailment. (detailed measurement methods and tolerances are in figures)

4.6 Cross Level

Cross level is the difference in height between the left and right rails at a point on the track.
Variation in cross level can lead to track buckling, undesirable oscillations, and instability for vehicles.
Measurement and recording of cross levels for the purpose of inspection and maintenance are described in detail. (includes procedures, tolerances, and standard intervals)

4.7 Twist

Twist is the rate of variation in cross level per meter.
This measurement is calculated over intervals of 3m from a reference point.
Twist analysis aids in identifying potential derailment risks.

4.7.1 Effect of Twist

Twist has a detrimental influence on running and constitutes a significant factor in derailment incidents.
Unbalanced loading of wheels due to uneven cross level can create derailment risk.

4.7.2 Calculating Effective Twist

Methods to accurately calculate effective twist are provided, considering distance from reference point, cross level readings, and wheel base dimensions

4.8 Track Alignment and Unevenness

Well-aligned tracks ensure comfort and safety, mitigating flange contact with the rails.
Track alignment and unevenness tolerances are specified for both broad gauge (B.G.) and metre gauge (M.G.).
Lateral and vertical alignment tolerances are defined (tables are referenced).

4.9 Creep

Longitudinal rail movement in tracks is termed as creep.
Creep can cause various issues in track structures.

4.9.1 Causes of Creep

Wave theory: describes rail movement as a wave that moves along the track with the train.
Change in temperature: expansion/contraction of rails due to temperature fluctuations.
Unbalanced traffic: unequal creep in different directions of traffic.
Other factors like loose fittings, poor sleeper quality, alignment issues, track gradients, rail life, and uneven sleeper spacing can also cause creep.

4.9.2 Effect of Creep

Creep leads to issues with sleepers, gauge and alignment, rail joints, track stability, movement of points and crossings, gaps in expansion, and potential for buckling.

4.9.3 Measurement of Creep

Procedures for measuring longitudinal rail movement are detailed (including placing posts, marking surfaces, and measuring intervals).

4.9.4 Remedial Steps against Creep

Preventive measures for creep include properly packing sleepers with ballast, maintaining track stability, addressing stiffness, soil quality, and ensuring correct interlocking.

4.10 Buckling of Track

Buckling results from excessive compressive forces in rails, particularly at junctions where one section of track is susceptible to creep.
Track laid on wooden sleepers with inadequate anchors and insufficient ballast, and track sections where welds connect different parts of the track are susceptible to buckling.
Shifts in sleepers related to poor ballast, loose fastenings, and improperly adjusted rail joints can induce buckling.

4.10.1 Conditions inducing Buckling

Inadequate expansion gaps.
Failure to mitigate creep over time.
Inappropriate rail joint lubrication.
Removal of rail closures from tracks.
Failure to maintain alignment or correct any deviations in track.

4.10.2 Precaution against Buckling

Implement preventive measures like greasing of fish plates, periodic joint gap surveys, ensuring proper fastening and lubrication , maintenance of expansion gaps, and taking preventive action against creep.

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Explore the key components of railway track structure in Chapter 4, focusing on formation, ballast, sleepers, fastenings, and rails. Understand the importance of these elements and the necessity of regular maintenance performed by engineers and track workers to ensure safety and efficiency. Get ready to test your knowledge on this essential aspect of railway engineering.