Question 1

Staggered rail joints: Where are staggered (alternate) rail joints most commonly provided to improve running and reduce impact?

Accepted Answer

Introduction / Context: In jointed track, rail joints present local discontinuities. If opposite joints are placed at the same section, the track experiences greater impact and potential alignment issues. Staggering the joints offsets them laterally between rails, improving load distribution. Given Data / Assumptions: Conventional jointed rail track with fish-plated joints. Curved alignment where dynamic effects are higher. Concept / Approach: On curves, lateral forces and rail creep are greater. Staggering joints ensures the wheel never encounters both rail ends simultaneously, reducing impact and improving ride. This practice mitigates the tendency for alignment kinks and uneven wear at the outer/inner rails of the curve. Step-by-Step Solution: 1) Identify higher dynamics on curves from centrifugal and steering forces.2) Avoid opposed joints at the same chainage by staggering.3) Benefit: reduced peak impact and improved durability. Verification / Alternative check: Maintenance guidelines recommend staggered joints especially on curves and critical approaches; welded rail further eliminates joints entirely, where possible. Why Other Options Are Wrong: Bridges and tunnels may have special jointing, but staggering is most critical on curves. Tangents pose less dynamic concern; staggering helps but is not as crucial as on curves. Common Pitfalls: Leaving opposite joints aligned on sharp curves—leads to rapid deterioration. Final Answer: On curves.

Question 2

Rail section designation: A rail section is generally designated by which parameter?

Accepted Answer

Introduction / Context: Rail sections are standardized and identified for procurement, design, and maintenance. A clear designation convention ensures uniformity across drawings, specifications, and logistics documentation. Given Data / Assumptions: Rails of different profiles (e.g., 60 kg/m, 52 kg/m) used for various load and speed categories. Section properties scale with mass per unit length. Concept / Approach: Rails are generally designated by their mass per metre (e.g., 60 kg/m). This single metric is practical and correlates with section modulus, stiffness, and load capability. While area and inertia are important for analysis, the mass-per-metre designation is universally recognized for identification. Step-by-Step Solution: 1) Recognize designation must be simple and uniformly applicable.2) Weight per metre succinctly captures section size and capacity.3) Hence rails are commonly referred to as ’’X kg/m’’ sections. Verification / Alternative check: Standards and catalogues list rail types by mass per metre, with associated drawings providing exact dimensions and properties. Why Other Options Are Wrong: Total batch weight or total length does not identify section. Area or inertia alone is not the standard naming convention in practice. Common Pitfalls: Confusing designation (kg/m) with total piece length (e.g., 13 m rails). Final Answer: Weight per metre length of the rail.

Question 3

In permanent-way design, a switch (or ‘‘Smitch’’) diamond crossing is adopted when the diamond angle is very small. For what limiting crossing angle (in degrees) is a switch diamond typically provided?

Accepted Answer

Introduction / Context: A diamond crossing is where two tracks intersect. When the crossing angle becomes very acute (small), ordinary fixed-rail diamonds suffer from impact, wear, and poor wheel guidance. Railways then adopt a switch (movable-point) diamond so flanges are guided positively. This question tests the threshold angle concept behind that choice. Given Data / Assumptions: Diamond angle is the included angle between the gauge faces at the intersection. The term “Smitch” is a common misspelling of “switch” diamond. Practice refers to typical main-line standards used in Indian-type trackwork. Concept / Approach: For very small angles the gap at the nose becomes long, causing poor support and high impact. Movable switch noses remove the gap and guide wheels. The commonly cited practical limit for using a switch diamond is about 6 degrees or smaller. Step-by-Step Solution: Identify the problem with small angles: longer unsupported gap and higher impact/wear.Check standard practice: switch diamond preferred below a limiting angle.Adopt the widely used threshold ≈ 6°. Verification / Alternative check: Track handbooks discuss changeover to switch diamonds in the 1 in 9–1 in 12 region (angles roughly ≤ 6–7°). Selecting 6° is a conservative and standard exam value. Why Other Options Are Wrong: 8° and 10° are too large; 4° or 2° are possible but overly restrictive and not the typical exam threshold. Common Pitfalls: Confusing crossing number (1 in N) with angle in degrees; assuming fixed diamonds suffice for very acute angles. Final Answer: 6°

Question 4

Placement rule for check rails at a crossing: how much of the check rail length is kept ahead (in front) of the nose of crossing?

Accepted Answer

Introduction / Context: Check rails are fitted opposite the crossing to control the wheel flange path and prevent it from striking the nose of crossing. Correct longitudinal placement of check rails is essential to safe guidance and reduced wear. Given Data / Assumptions: Standard turnout/crossing geometry is considered. “Ahead of the nose” means toward the approaching traffic direction. Concept / Approach: The greater portion of a check rail must lie ahead of the nose to guide the wheel well before it reaches the critical crossing region. A commonly used rule-of-thumb is to place about two-third of its total length in front of the nose, the remaining one-third trailing behind. Step-by-Step Solution: Identify functional requirement: early positive flange guidance.Adopt standard proportion: 2/3 ahead, 1/3 behind.Select the option matching this proportion. Verification / Alternative check: Typical permanent-way manuals illustrate check rail layouts with longer leading lengths to align and restrain flanges prior to the crossing gap. Why Other Options Are Wrong: One-third ahead is insufficient; three-fourths ahead is excessive and may reduce trailing protection; symmetric placement does not prioritize the critical approach area; all-behind offers no advance guidance. Common Pitfalls: Confusing “ahead” with “behind”; overlooking directionality of traffic dominance in layouts. Final Answer: Two-third of its length ahead of the nose

Question 5

On Indian Broad Gauge, gauge widening on curves is generally provided when the degree of curve is:

Accepted Answer

Introduction / Context: Gauge widening on sharp curves helps reduce flange binding and limits wheel/rail wear. It is a standard geometric correction applied on tighter curves in Indian Railways. Given Data / Assumptions: Degree of curve is measured by standard railway convention. Broad Gauge practice is referenced. Typical threshold used in exams is around 3°. Concept / Approach: Tighter curves (higher degree) cause higher lateral forces and flange contact. A small intentional widening of gauge eases passage, especially for long-wheelbase rolling stock. Hence, beyond a threshold sharpness, widening is provided. Step-by-Step Solution: Recognize that need grows with curvature tightness.Adopt exam-standard threshold: provide widening for curves > 3°.Choose the option that states “More than 3°”. Verification / Alternative check: Design tables specify actual widening versus degree; many texts quote 3° as the indicative starting point for BG, with greater widening as degree increases. Why Other Options Are Wrong: “3° or less” is usually unnecessary; “between 3° and 4° only” is too restrictive; “not required” is incorrect; “more than 1° on straight track” is nonsensical. Common Pitfalls: Confusing degree of curve with cant; applying excessive widening without checking limits and wheelbase considerations. Final Answer: More than 3°

Question 6

Identify the correct description of steel sleepers used on Indian Railways.

Accepted Answer

Introduction / Context: Sleepers provide support and gauge restraint for rails. Steel sleepers commonly used in India are pressed trough sections designed to give stiffness, fastening support, and ballast interlock. Given Data / Assumptions: Standard Indian steel sleeper design. Thickness ~6 mm is typical for pressed trough sections. Concept / Approach: Pressed trough steel sleepers have ends bent up to improve strength, provide bearing area at rail seats, and contain ballast. The shape increases section modulus while keeping weight manageable, and accommodates clips or fastenings. Step-by-Step Solution: Recall standard profile: pressed trough shape.Ends are bent upward (not downward) to form upstands.Confirm typical plate thickness ≈ 6 mm. Verification / Alternative check: Manufacturers’ drawings show characteristic trough with upturned ends and rail seats prepared for fastenings. Why Other Options Are Wrong: Solid rectangular sections are uneconomical; ends bent down is not the standard; pipe-type and cast blocks are not the typical steel sleeper solution. Common Pitfalls: Confusing steel sleepers with cast-iron or PSC sleepers; misremembering the direction of end bends. Final Answer: 6 mm thick pressed steel trough with ends bent up

Question 7

Where is the standard rail cant (tilt) of 1 in 20 provided in track construction?

Accepted Answer

Introduction / Context: Rails are canted inward at 1 in 20 to align wheel–rail contact near the rail head center, reducing wear and improving stability. Understanding where and how this inclination is implemented is important for design and maintenance. Given Data / Assumptions: Cant 1 in 20 is standard for BG flat-bottom rails. Cant is achieved by inclined rail seats or fittings, not by tilting the running surface of the rail head itself. Concept / Approach: The inclination is built into the support components (chairs, bearing plates, or sleeper seats) so that the rail is installed at the required angle. The rail head remains a manufactured profile; its running surface is not machined to provide cant. Step-by-Step Solution: Identify the purpose of cant: better flange/rail contact.Locate where cant is introduced: at the seats/fastenings.Conclude: provided at rail seats on sleepers/chairs/plates. Verification / Alternative check: Standard drawings show inclined rail seats; fastening systems (e.g., Pandrol clips with baseplates) preserve the 1 in 20 inclination. Why Other Options Are Wrong: Top of rail head is not where cant is formed; limiting to joints or only very high cants is incorrect; ballast trimming cannot provide precise inclination. Common Pitfalls: Assuming the rail profile itself is tilted by milling; overlooking that PSC sleepers often have cast-in inclined seats. Final Answer: At the rail seats in bearing plates, chairs, and metal sleepers (not on the rail head itself)

Question 8

To reduce impact on the nose of crossing, wing rails are “ramped” so that the nose sits slightly lower than the wing rails. By how much is the nose typically kept lower?

Accepted Answer

Introduction / Context: At a crossing (frog), wheel transfer from wing rail to nose can cause impact. A small vertical offset (ramping) is used so the wing rail carries the wheel slightly before the nose engages, protecting the nose from direct hammering. Given Data / Assumptions: Standard BG turnout and crossing practice. Typical workshop/maintenance tolerances apply. Concept / Approach: Providing a small lead height to wing rails reduces impact on the nose. A commonly adopted nominal difference is about 6 mm, balancing reduced impact with smooth transition. Step-by-Step Solution: Understand objective: protect nose by pre-support on wing rail.Adopt standard offset value.Choose 6 mm as the typical practice. Verification / Alternative check: Turnout maintenance manuals specify permissible height differences and ramp lengths; 6 mm appears as a standard nominal figure. Why Other Options Are Wrong: 3–5 mm may be insufficient in many practices; >6 mm could cause a perceptible step and ride deterioration. Common Pitfalls: Assuming no ramping is needed; over-ramping causing dynamic shock. Final Answer: 6 mm

Question 9

For which sleeper type is sand commonly used as ballast (especially in arid areas or light-duty track)?

Accepted Answer

Introduction / Context: Ballast characteristics affect drainage, interlock, and track resilience. While broken stone is standard, sand ballast has been used on certain routes, particularly in desert or low-axle-load conditions, and with specific sleeper types. Given Data / Assumptions: Historical Indian practice where cast-iron (CI) pot or plate sleepers have been used. Light to moderate traffic contexts; arid zones with abundant sand. Concept / Approach: CI sleepers, with their seat geometry and bearing characteristics, can work with sand ballast where interlocking requirements are modest. Wooden and steel sleepers generally prefer angular stone for adequate lateral resistance and drainage; sand lacks the shear interlock and can migrate. Step-by-Step Solution: Match ballast properties to sleeper support needs.Recognize CI sleeper compatibility with sand in legacy practice.Select “Cast-iron sleepers”. Verification / Alternative check: Older permanent-way manuals and case studies in desert sections document use of sand ballast with CI sleepers. Why Other Options Are Wrong: Wood and steel sleepers generally require crushed stone for stability; “all equally” is not true; “none” ignores documented practice. Common Pitfalls: Assuming sand performs like broken stone; overlooking drainage and fouling issues with fine materials. Final Answer: Cast-iron sleepers

Question 10

Rail diamond geometry: if G is the gauge (mm) and α is the crossing angle, what is the distance along the through rail between the nose of the acute crossing and the nose of the obtuse crossing?

Accepted Answer

Introduction / Context: Diamond crossings combine an acute and an obtuse crossing. Designers frequently need the longitudinal spacing between the two noses measured along the non-diamond (through) rail for setting component positions and check rails. Given Data / Assumptions: G is the gauge distance between gauge faces. α is the diamond crossing angle between gauge faces. Simple right-triangle trigonometry applies to plan geometry. Concept / Approach: Consider the plan geometry triangle formed by the gauge distance as the side opposite the angle α, and the required spacing along the rail as the adjacent side. The relation between opposite and adjacent through tangent/cotangent gives the spacing. Step-by-Step Solution: Let required spacing L be adjacent to α; gauge G is opposite to α.tan α = opposite / adjacent = G / L.Therefore L = G / tan α = G cot α. Verification / Alternative check: Check limiting behavior: as α decreases (sharper diamond), tan α decreases and L increases, which matches intuition that noses are farther apart. Why Other Options Are Wrong: G tan α or G sin α would reduce spacing with sharper angle incorrectly; G cos α does not reflect the opposite/adjacent relationship; G/tan α is algebraically the same as G cot α but not listed verbatim in most formula sheets—select the canonical expression. Common Pitfalls: Mixing α with its complement; confusing gauge G with track center spacing. Final Answer: G cot α

Question 11

Permissible gauge under loaded condition (tolerance) on a Broad Gauge track is typically limited to which of the following values?

Accepted Answer

Introduction / Context: Gauge tolerance under load ensures that track retains safe wheel guidance despite elastic deformations. Indian Railways specifies acceptable variations so that maintenance targets are clear and rolling stock safety margins are preserved. Given Data / Assumptions: B.G. track under service loading. Typical permissible widening is small and positive; tightening (negative) is rarely specified as desirable under load. Concept / Approach: Under load, rail fastenings and sleeper seats experience elastic movement. Standards set a small upper bound to gauge widening—commonly taken as about +6 mm for exam purposes—beyond which corrective maintenance is required. Step-by-Step Solution: Identify that tolerance is a small positive value (widening) under load.Recall conventional exam value ~ +6 mm.Select G + 6 mm. Verification / Alternative check: Track maintenance manuals and permanent-way instructions provide tables of tolerances; +6 mm is a representative upper limit used in many contexts for BG. Why Other Options Are Wrong: +3 mm is tighter than typical exam standard; zero tolerance is impractical; negative tolerance (tightening) is unsafe; −20 mm is grossly unacceptable. Common Pitfalls: Confusing construction tolerances (no load) with service tolerances (under load); misapplying gauge-widening for curves to straight track tolerances. Final Answer: G + 6 mm

Question 12

On Indian Railways, the angle of crossing associated with the V-crossing (frog) is commonly calculated by which method?

Accepted Answer

Introduction / Context: The angle of crossing determines the geometry of the V-crossing (frog) in a turnout or diamond. Several geometric conventions exist for defining and computing this angle for design and manufacture. Given Data / Assumptions: Indian Railways practice allows more than one accepted method in standards and literature. Focus is on common calculation conventions rather than numerical value. Concept / Approach: Two widely taught approaches are Cole’s method and the centre-line method. Both yield consistent, practically usable definitions for specifying and checking crossings. The isosceles-triangle method is more of a didactic geometric construct and not the usual specification basis. Step-by-Step Solution: Identify practices recognized by Indian standards and texts.Acknowledge that Cole’s and centre-line methods are both used.Select the option that includes both. Verification / Alternative check: Handbooks present tables with crossing numbers convertible between methods for checking and procurement. Why Other Options Are Wrong: Using only one of the two omits a commonly accepted method; the isosceles-triangle method is not the common specification basis; “parabolic transition method” is unrelated to crossing angle definition. Common Pitfalls: Confusing crossing angle with turnout angle or switch angle; misinterpreting crossing number (1 in N) as a direct degree measure. Final Answer: Both Cole’s and Centre-line methods

Question 13

Rail section design on Indian Railways: Which factors primarily govern the choice of rail weight and cross-section for a track?

Accepted Answer

Introduction / Context: The weight and cross-section of rails form the backbone of track design. On Indian Railways, selecting the correct rail section is a systems decision that balances safety, durability, and economy. Multiple factors influence bending stresses, wear, and stability of the permanent way. Given Data / Assumptions: Track gauge determines overall geometry and load distribution requirements. Speed of trains affects dynamic augment and impact loads on rails. Sleeper spacing influences the effective span of rail between supports. Type of rail (e.g., flat-footed, head-hardened) changes performance and permissible stresses. Concept / Approach: Rail acts as a continuous beam supported by sleepers. Bending moment is sensitive to sleeper spacing and axle load; dynamic effects scale with speed; and broader gauge typically accompanies higher axle loads and wider loading conditions. Hence the section must be chosen by considering all these together rather than any single factor. Step-by-Step Solution: Relate gauge to structural demand: broader gauges usually carry heavier and faster traffic, requiring heavier sections.Account for speed: higher speed increases dynamic forces and rail head wear, warranting a heavier or head-hardened section.Consider sleeper spacing: a larger spacing increases rail span and bending moment, necessitating higher section modulus.Include rail type/material treatment: selection affects fatigue life and contact fatigue resistance.Therefore, the correct choice is the option that includes all factors. Verification / Alternative check: Track design manuals coordinate axle load, speed, sleeper density, and rail metallurgy to specify rail sections (for example, 52 kg/m or 60 kg/m rails on BG for higher speeds and axle loads). Why Other Options Are Wrong: Gauge only: Ignores speed and sleeper effects. Speed only: Omits structural span from sleeper spacing and gauge constraints. Sleeper spacing only: Lacks speed and gauge considerations. Type of rails only: A material/property choice, not the sole sizing driver. Common Pitfalls: Over-reliance on a historical section without checking updated speed/axle-load regimes; disregarding tighter sleeper spacing that could allow lighter sections. Final Answer: all the above

Question 14

Ballast load dispersion assumption: For even distribution of load through the ballast, what angle to the vertical is commonly assumed for load dispersal?

Accepted Answer

Introduction / Context: In railway track design, the load from wheel to rail, rail to sleeper, and sleeper to ballast is idealized using a dispersion angle. This aids quick estimation of contact pressures and formation design without complex numerical models. Given Data / Assumptions: Engineering idealization of ballast pressure spread is required. Angle measured from the vertical to the sides of the load pyramid is used. We assume typical granular ballast behaviour under service compaction. Concept / Approach: A 45° to the vertical dispersion is a widely adopted rule-of-thumb. It implies that for every unit of vertical depth, the effective load-spread increases by one unit laterally, forming an isosceles right-angled load dispersion pyramid below the sleeper. Step-by-Step Solution: Recognize that ballast transmits load through interlock and friction.Adopt a conservative, symmetric spread: 45° on either side of the vertical.Use this to size ballast depth and predict formation pressure. Verification / Alternative check: Track design texts and empirical practice commonly use 1H:1V (i.e., 45°) dispersion beneath sleepers. More refined analyses may modify the angle for ballast condition but 45° is the standard preliminary assumption. Why Other Options Are Wrong: 30°: Unrealistically steep; underestimates lateral spread, overestimates pressure below. 60°: Too shallow; overestimates spread and may underestimate formation pressure. None of these: Not correct because 45° is the established assumption. Common Pitfalls: Confusing 45° to the vertical with 45° to the horizontal; forgetting that fouled ballast or geogrid reinforcement may change effective spread in practice. Final Answer: 45° to the vertical

Question 15

Provision of check rails on sharp curves (Broad Gauge): Beyond what curve sharpness (degree of curve) are check rails provided on the inner side of the inner rail?

Accepted Answer

Introduction / Context: Check rails are installed on sharp curves to improve flange guidance and reduce the risk of flange climb, rail wear, and rolling contact fatigue. On Broad Gauge (BG), standards prescribe a threshold curve sharpness for fitting check rails. Given Data / Assumptions: Curve sharpness is expressed as degree of curve (central angle subtended by standard chord). Inner side of inner rail is the gauge face reference location. Standard Indian practice for BG is considered. Concept / Approach: As curvature increases, the angle of attack of wheelsets grows, increasing flange contact and risk at the gauge corner. Check rails restrain the flange path, reducing lateral forces and wear. Thresholds are set so that only sufficiently sharp curves receive check rails, optimizing maintenance cost and safety. Step-by-Step Solution: Identify BG threshold for check-rail provision.Use standard rule: provide check rails on curves sharper than about 5° on BG, depending on traffic and speed.Choose 5° as the specified value in the options. Verification / Alternative check: Maintenance and P&Way manuals corroborate that about 5° is the commonly cited trigger for check rails on BG, with local adjustments for traffic density. Why Other Options Are Wrong: 3°: Too mild for mandatory check rails. 6° or 8°: These are sharper curves; waiting until these values could increase wear risk. Common Pitfalls: Confusing BG with MG/NG thresholds; assuming check rails are needed on all curves, which is uneconomical and unnecessary. Final Answer: 5°

Question 16

Sleeper spacing along a rail: Where is sleeper spacing typically kept closer for better support and reduced bending in the rail?

Accepted Answer

Introduction / Context: Rails behave like beams on elastic supports. Where bending moments or deflections are higher—such as near joints in jointed track—engineering practice modifies sleeper spacing to control stresses and improve service life. Given Data / Assumptions: Jointed track with fish-plated joints (or any location where end conditions create higher bending). Uniform axle load and sleeper type. Objective is to reduce rail end deflection and impact loads. Concept / Approach: Closer spacing near joints reduces the effective span of the rail at its weakest location (the joint), thereby reducing bending moment (M) and deflection (y). This also minimizes battering at joints and improves ride quality. Step-by-Step Solution: Identify critical zones: rail ends/joints.Reduce sleeper spacing at these zones to decrease unsupported length.Maintain more regular spacing elsewhere to optimize material usage. Verification / Alternative check: Field practice and permanent-way manuals specify closer spacing near joints (for example, additional sleepers or closer spacing around joint sleepers) to handle higher impact and bending. Why Other Options Are Wrong: Uniform spacing everywhere ignores joint vulnerability and increases maintenance. Closer at the middle of rails is unnecessary; mid-span bending is managed by standard spacing. None of these is incorrect because closer spacing near joints is the accepted norm. Common Pitfalls: Applying uniform spacing from continuous welded rail to jointed rail without adjustment; forgetting to pair joint sleepers for stiffness. Final Answer: near rail joints, is kept closer

Question 17

Railway yard planning: Which statements about gathering lines and economical yard layout are correct?

Accepted Answer

Introduction / Context: Railway yards must fit many sidings into limited space and still allow efficient movements. Gathering lines (lead lines) and the angles they make with sidings determine both the capacity and economy of layout. Given Data / Assumptions: Multiple parallel sidings branch off from a lead line (gathering line). Main track access is required. Limiting angle concept: the steepest practical turnout/gathering angle permitted by standards and operational constraints. Concept / Approach: A gathering line collects sidings and connects them to a main line. If the gathering line is laid diagonally, sidings placed farther away have shorter usable length unless geometry is compensated. Using a diagonal at one end and a parallel gathering line at the other balances lengths. Working at the limiting angle economizes space and turnout usage. Step-by-Step Solution: Define gathering line as the lead that provides access from multiple sidings to the main line.Note that a diagonal lead causes length reduction for sidings farther from the main.Provide a parallel gathering line opposite the diagonal end to equalize siding lengths.Adopt limiting angle to minimize land take and material while respecting turnout geometry. Verification / Alternative check: Yard design handbooks illustrate equalizing siding lengths using combined diagonal and parallel leads, and recommend near-limiting angles for compact yet functional yards. Why Other Options Are Wrong: Each individual statement is correct; hence selecting any single one underestimates the complete design guidance. The only comprehensive choice is “All the above.” Common Pitfalls: Using a single diagonal without compensating geometry; ignoring operational clearances (fouling marks) that further reduce effective siding length. Final Answer: All the above.

Question 18

Track circuits and welded rails: How is continuity of electric current maintained across welded rail joints?

Accepted Answer

Introduction / Context: Track circuits use the running rails as conductors for train detection and signaling. Reliable electrical continuity across joints is essential, especially with welded joints or insulated joints placed for block boundaries. Given Data / Assumptions: Continuous welded rail track with occasional insulated joints as required by signaling design. Need to maintain low-resistance return path for current. Concept / Approach: Bond wires (rail bonds) are employed by welding or brazing their ends to the web/foot of adjacent rails, providing a robust, low-resistance parallel path that survives vibration and weathering. This ensures circuit reliability even if the physical joint area has higher resistance. Step-by-Step Solution: Identify the need: continuity across joint areas for signaling current.Provide rail bonds: weld a flexible copper bond wire to both rails across the joint.Verify continuity and resistance meet signaling specifications. Verification / Alternative check: Routine testing with ohmmeters confirms low resistance across bonded joints; visual inspection ensures weld integrity and strain relief is adequate. Why Other Options Are Wrong: Insulated plate underneath rails: provides no electrical bonding; it insulates from sleepers or baseplates, not rail-to-rail. Insulation in expansion gaps: increases resistance rather than maintaining continuity; used only where isolation is desired. None of these: incorrect because bonding wires are standard practice. Common Pitfalls: Using mechanical clamps instead of welded bonds in high-vibration areas; neglecting redundancy bonds on vital circuits. Final Answer: welding ends of a wire to each rail

Question 19

Pot sleepers (two-bowl type): The total effective bearing area of both bowls of a pot sleeper, when compared with a wooden sleeper, is

Accepted Answer

Introduction / Context: Pot sleepers (cast-iron, two-bowl type) were historically used on Indian Railways. Their design intent was to provide bearing performance comparable to timber sleepers by distributing load over an equivalent bearing area. Given Data / Assumptions: Two bowls support the rail through chairs or keys. Comparison is with a standard wooden sleeper under similar loading. Concept / Approach: The total effective bearing area (sum of both bowls in contact with ballast) is chosen to match the contact area of a timber sleeper so that ballast pressure levels are similar, avoiding overstressing of formation and ensuring comparable settlement behaviour. Step-by-Step Solution: Recognize that bearing area determines average ballast pressure p = Load / Area.Design intent keeps p similar between sleeper types to maintain track stability.Hence the two bowls together provide an area approximately equal to that of a timber sleeper. Verification / Alternative check: Historic specifications targeted equality of bearing pressure, which implies near-equal effective bearing areas for comparable axle loads. Why Other Options Are Wrong: Slightly more/less: Would lead to different ballast pressures and performance; not the intent for interchangeable usage. None of these: Incorrect because equivalence was the design goal. Common Pitfalls: Comparing plan area rather than effective bearing area actually contacting ballast; ignoring fouling or consolidation which changes effective support. Final Answer: equal to that of a wooden sleeper

Question 20

Sleeper cant near the rail seat: On either side of the centre line of the rail, a cant of 1 in 20 is provided in the sleeper for a distance of

Accepted Answer

Introduction / Context: Rail seats on sleepers are adzed or formed to a 1 in 20 cant to match the rail base inclination. This improves wheel–rail contact by aligning the rail head with the conicity of wheels and reduces flange wear and rolling contact stresses. Given Data / Assumptions: Standard flat-bottom rail with 1 in 20 base inclination. Timber or concrete sleeper with defined rail seat width. Distance measured from the rail centre line on both sides. Concept / Approach: The adzed/canted area must extend sufficiently beyond the rail base to ensure uniform support and prevent edge crushing of sleeper fibres or pads. A typical provision is 150 mm on either side of the rail centre line, covering and slightly exceeding the rail base width for robust support. Step-by-Step Solution: Identify rail base width and pad/plate footprint.Provide a canted seat width that fully supports the rail base with margin.Adopt the standard value of 150 mm from rail centre line on each side. Verification / Alternative check: Permanent-way specifications list the canted seat width near 300 mm total around the rail centre line, i.e., 150 mm on each side, ensuring full bearing under dynamic loads. Why Other Options Are Wrong: 165 mm, 175 mm, 185 mm: Wider seats may be used in special designs, but the standard provision is 150 mm each side. Common Pitfalls: Confusing total seat width with distance from centre line; mixing the 1 in 20 rail seat cant with track superelevation (cant) on curves. Final Answer: 150 mm

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