Question 1

Simple curve geometry for track versine: If L is the chord length of a rail on a circular curve of radius R, what is the versine (mid-ordinate) h?

Accepted Answer

Introduction / Context: Versine (sagitta) measurements are widely used in railway track geometry to quantify curvature using a chord and a mid-ordinate. This relation allows quick field checks without directly measuring radius R. Given Data / Assumptions: Circular curve of constant radius R. Chord length along the rail = L. Versine h is the mid-ordinate from the chord to the arc. Concept / Approach: From circle geometry, the exact sagitta is h = R − sqrt(R^2 − (L/2)^2). For railway practice (L small relative to R), the binomial approximation gives the standard working formula h ≈ L^2 / (8R). This is the textbook relation used for versine-based curvature checks. Step-by-Step Solution: Start with exact: h = R − sqrt(R^2 − (L/2)^2).Use approximation for small (L/R): sqrt(R^2 − (L/2)^2) ≈ R − (L^2 / (8R)).Therefore, h ≈ L^2 / (8R). Verification / Alternative check: For a sample case (e.g., L = 10 m, R = 1000 m), exact and approximate h values are nearly identical, validating the approximation for typical track work where R is large compared to L. Why Other Options Are Wrong: Forms like 2R/L^2, R^2/(8L), 8R/L are dimensionally inconsistent for length. L/(2R) is linear in L; sagitta scales with L^2 for small chords. Common Pitfalls: Using the exact expression unnecessarily in routine checks, adding complexity. Confusing versine with mid-chord offset for alignment deviations (a different application). Final Answer: h = L^2 / (8R)

Question 2

Railway wheel–rail interaction: What outward tread slope is provided on railway wheels to achieve self-centering and smooth curving?

Accepted Answer

Introduction / Context: Wheel tread conicity (outward slope) is fundamental to vehicle dynamics. It enables self-centering on straight track and reduces flange contact on curves, improving ride, reducing wear, and limiting hunting at speed. Given Data / Assumptions: Standard railway wheelsets on conventional track. Question asks the nominal outward slope used as a standard. Concept / Approach: With a coned tread, lateral shift changes rolling radii of the two wheels: the wheel with the larger effective radius runs on the outer rail, naturally steering the wheelset into the curve. The widely adopted nominal slope is 1 in 20, balancing curving ability (reduced flange contact) and high-speed stability. Step-by-Step Solution: Recall standard conicity: 1 in 20 is common for freight and passenger operations on conventional track.Check alternatives: steeper slopes raise hunting; shallower slopes weaken self-centering.Conclude 1 in 20 is the accepted value. Verification / Alternative check: Vehicle/track dynamics references and permanent-way specifications list 1 in 20 as the nominal tread slope; variants exist for special cases but 1 in 20 is the textbook norm. Why Other Options Are Wrong: 1 in 10, 1 in 15: Too steep; can increase sensitivity and hunting. 1 in 25, 1 in 30: Too shallow; poorer self-centering and more flange contact on curves. Common Pitfalls: Confusing rail head cant with wheel tread slope; both may use 1 in 20 but are different design parameters. Final Answer: 1 in 20

Question 3

Permanent-way fastenings: Bearing (base) plates are used to fix which rail–sleeper combination?

Accepted Answer

Introduction / Context: Bearing plates (base plates) distribute load from the rail to the sleeper, reduce seat crushing, and provide better spike/clip anchorage. Knowing where they are used is vital for understanding sleeper performance and fastening selection. Given Data / Assumptions: Wooden sleepers are susceptible to seat indentation. Flat-footed rails have a broad base suitable for plate-and-spike/clip fastening. Bull-headed/double-headed rails historically sit in chairs. Concept / Approach: On timber sleepers, flat-footed rails typically require bearing plates to spread load and protect the wood. Bull-headed/double-headed rails use iron chairs keyed to the rail and do not rely on simple bearing plates on timber. Cast-iron or concrete sleepers integrate the bearing surface within their design. Step-by-Step Solution: Identify the combination using plates: flat-footed rail + timber sleeper.Eliminate chair-based systems (BH/DH) and designed seats in metal/concrete sleepers.Select Option A. Verification / Alternative check: Permanent-way manuals specify base plates under flat-bottom rails on timber to preserve sleeper life and maintain gauge. Why Other Options Are Wrong: Double headed / Bull headed to wood: Typically use chairs, not plates. Flat-footed to cast iron sleepers: Seats are integral; separate bearing plates are generally unnecessary. None of these: Incorrect because Option A is standard practice. Common Pitfalls: Confusing chairs with base plates; they serve different rail sections. Final Answer: flat footed rails to the wooden sleepers

Question 4

Crossover geometry with an intermediate straight: If D is the centre-to-centre distance between two parallel tracks of gauge G and the crossing is of number N, what is the total length of the crossover (from commencement to termination)?

Accepted Answer

Introduction / Context: Designing a crossover between parallel tracks requires estimating the overall length from the first turnout to the second, including the intermediate straight. The relation depends on the track spacing D, the gauge G, and the crossing number N (where tan α ≈ 1/N for small angles). Given Data / Assumptions: Two parallel tracks, centre spacing = D. Track gauge = G. Crossing of number N with an intermediate straight between turnouts. Concept / Approach: The total crossover length combines: (i) the geometrical lead components associated with each turnout, and (ii) the intermediate straight portion needed for gauge and clearances. In standard derivations using the relationship of offsets and the crossing angle α (with N = 1/tan α), the algebraic sum yields a compact expression in D, G, and N for planning layout length. Step-by-Step Solution: Relate turnout geometry to crossing number: small-angle approximations tan α ≈ 1/N.Assemble length contributions from both turnouts and the intermediate straight segment that ensures parallelism and clear running.Collect terms in D and G to obtain a closed-form estimate, leading to DN + G(2N + 1 + N^2). Verification / Alternative check: Dimensional sense-check: each term results in a length; the expression increases with larger N (shallower crossings) and with greater spacing D, aligning with design intuition. Why Other Options Are Wrong: Forms with fewer N-dependent terms underestimate the turnout leads. Excess terms or incorrect coefficients do not match standard geometric derivations for crossovers with a straight between turnouts. Common Pitfalls: Confusing geometric turnout lead with switch length or ignoring the intermediate straight portion. Misinterpreting crossing number N (it is not the same as cant or versine parameters). Final Answer: DN + G (2N + 1 + N^2)

Question 5

Track ballast quantity: What is the quantity of stone ballast required per metre of tangent track (standard practice)?

Accepted Answer

Introduction / Context: Ballast provides load distribution, drainage, resilience, and track stability. Estimating the required volume per metre is essential for budgeting, logistics, and maintenance scheduling for tangent (straight) track sections. Given Data / Assumptions: Question asks for typical ballast volume per metre of tangent track. Standard sleeper density, shoulder width, and ballast cushion depth are implied by conventional practice. Concept / Approach: Ballast volume per metre is a function of sleeper spacing, ballast cushion thickness under sleepers, and shoulder/side slope widths. Tangent track (no extra for curvature) represents the baseline requirement. Among close values provided, the conventional rounded figure used in planning references is taken as the correct choice. Step-by-Step Solution: Consider typical design: adequate ballast cushion, sleeper spacing, and shoulders.Compare options clustered around ~1.1–1.15 m^3/m.Select the standard planning value: 1.15 m^3 per metre tangent. Verification / Alternative check: Practical design manuals often quote a planning figure close to 1.15 m^3/m for straight track, with adjustments for curvature, heavier axle loads, or different sleeper types. Why Other Options Are Wrong: 1.11–1.14 m^3: Slight underestimates relative to the commonly adopted planning figure. Common Pitfalls: Treating this as an exact invariant; in practice, ballast volume varies with sleeper type, cushion thickness, and ballast profile standards. Final Answer: 1.15 m3

Question 6

Vertical curve design on rail alignment: A 0.70% upgrade meets a 0.65% downgrade at a summit. If the permitted rate of change of grade is 0.10% per chain, what is the required length of the vertical curve?

Accepted Answer

Introduction / Context: Vertical curves provide smooth transitions between grades for ride comfort, safety, and sight distance. Designers limit the rate of change of grade to a maximum per unit length (often per chain in railway practice). Given Data / Assumptions: Upgrade = +0.70%. Downgrade = −0.65% (summit curve). Allowable rate of change = 0.10% per chain. 1 chain is the reference length unit used for the rule. Concept / Approach: The total algebraic change in grade across the curve equals the sum of magnitudes at a summit (since signs are opposite): Δg = 0.70% + 0.65% = 1.35%. Minimum curve length L (chains) is Δg divided by the permitted rate per chain. Step-by-Step Solution: Compute Δg: 0.70 + 0.65 = 1.35%.Permitted rate = 0.10%/chain.L = 1.35 / 0.10 = 13.5 chains.Adopt ≥ computed length → 14 chains (rounded up). Verification / Alternative check: Check limiting rate using 14 chains: 1.35/14 ≈ 0.096%/chain ≤ 0.10%/chain, so the requirement is satisfied. Why Other Options Are Wrong: 10, 12 chains: Too short; exceed the permitted rate. 16, 18 chains: Acceptable but longer than necessary in typical exam context seeking the minimum satisfying design. Common Pitfalls: Subtracting grades (appropriate for valley combinations) instead of adding for a summit. Failing to round up to meet the limit. Final Answer: 14 chains

Question 7

Ballast grading for flat-bottom rail sleepers: What is the maximum size of ballast recommended for flat-bottom sleeper tracks?

Accepted Answer

Introduction / Context: Ballast grading influences drainage, load distribution, track resilience, and maintenance. The maximum nominal size must be selected to prevent fouling while ensuring interlock and ease of tamping around flat-bottom sleeper seats. Given Data / Assumptions: Standard track with flat-bottom sleepers (timber/concrete/steel bearer types supporting flat-footed rails). Question targets the upper size limit of ballast grading. Concept / Approach: Railway specifications commonly use coarse ballast up to a nominal maximum of around 50 mm for main lines. This offers good interlock and drainage while avoiding oversize that can hinder compaction or damage components. Smaller maxima (e.g., 40 or 33 mm) may be used in special cases but 50 mm is the typical main-line value presented in standard questions. Step-by-Step Solution: Review common standards: 50 mm nominal maximum for mainline ballast.Select the nearest matching option. Verification / Alternative check: Permanent way specifications across several administrations align around a 50 mm top size for mainline tracks using flat-bottom sleepers. Why Other Options Are Wrong: 40, 33, 25, 20 mm: Finer gradings; may be used for specific cases or secondary lines, but not typically the mainline maximum referenced in standard exam practice. Common Pitfalls: Confusing nominal maximum size with average particle size or grading envelope limits. Final Answer: 50 mm

Question 8

Switch setting practice: A kink is made in stock rails ahead of the toe of switch at what standard distance?

Accepted Answer

Introduction / Context: Accurate switch geometry ensures smooth entry to the turnout, proper contact between switch and stock rail, and minimized wear. A small intentional kink in the stock rail ahead of the toe helps achieve the desired fit and gauge through the switch zone. Given Data / Assumptions: Standard practice for conventional turnouts. Distance is measured along the stock rail ahead of the toe of switch. Concept / Approach: The kink location is chosen to provide a subtle alignment change that assists the switchblade in closing properly, maintaining gauge and contact without creating abrupt geometry. The commonly adopted nominal distance in many standard drawings for conventional turnouts is about 20 cm ahead of the toe. Step-by-Step Solution: Recall standard switch setting details from turnout drawings.Identify the nominal distance used: 20 cm.Select 20 cm as the correct option. Verification / Alternative check: Turnout assembly and inspection manuals indicate a short, controlled kink ahead of the toe near 200 mm to assure seating and running quality. Why Other Options Are Wrong: 10 or 15 cm: Too close; may not provide adequate alignment transition. 30 or more: Excessive; risks disturbing approach geometry and wheel guidance. Common Pitfalls: Treating the kink as a sharp bend; it is a subtle, controlled change to aid switch closure. Final Answer: 20 cm

Question 9

Rail joints: At a standard rail joint, the adjoining rail ends are connected with a pair of fishplates and how many fish bolts?

Accepted Answer

Introduction / Context: Where continuous welded rail is not provided or during temporary works, rail joints are made using fishplates and bolts. The standard number of bolts is critical for maintaining alignment, transmitting forces, and ensuring joint integrity under traffic loads. Given Data / Assumptions: Conventional joint with two fishplates (one on each side of the web). Standard mainline configuration (not a special insulated or expansion joint). Concept / Approach: A typical fishplated joint uses four bolts—two per fishplate—arranged to clamp the rail web securely. This provides adequate stiffness and load transfer for ordinary service conditions in jointed track sections. Step-by-Step Solution: Recognize standard hole patterns in fishplates (four-hole plates are common).Two plates × two bolts each → four bolts total.Select '4 fish bolts' as correct. Verification / Alternative check: Permanent-way standards and track maintenance manuals confirm four-bolt joints for most conventional applications. Why Other Options Are Wrong: 2 bolts: Insufficient clamping for standard joints. 6 or 8 (or 12) bolts: Non-standard for basic joints; used only in special heavy-duty or engineered joints. Common Pitfalls: Confusing with insulated or expansion joints which may have different patterns. Final Answer: 4 fish bolts

Question 10

In railway engineering, what are the principal purposes served by coning of wheels on rolling stock (state the best comprehensive choice)?

Accepted Answer

Introduction / Context: Coning of wheels refers to giving the tread of railway wheels a slight taper instead of making it perfectly cylindrical. This small geometric refinement has multiple functional advantages in track–vehicle interaction. The question tests whether you recognise that coning serves several related purposes in stability, guidance, and wear reduction. Given Data / Assumptions: Wheel treads are coned (tapered), not flat. We are assessing benefits: lateral guidance, ride smoothness, and rail wear. Track is conventional with rails set to gauge and a small cant on curves. Concept / Approach: Because the tread is coned, a small lateral shift changes the effective rolling radius of the two wheels on an axle. The wheel that moves outward runs on a larger radius, and the inner wheel runs on a smaller radius. This self-steering effect helps the axle recentre itself, limits hunting, improves smoothness, and reduces flange–rail contact that would otherwise accelerate wear on the rail inner faces. Step-by-Step Solution: Identify purpose 1: lateral guidance. Coning creates a restoring tendency that resists uncontrolled side wander.Identify purpose 2: smooth running. Reduced flange impacts and better self-steering lower vibrations and ride harshness.Identify purpose 3: wear reduction. Less flange grinding on the gauge face decreases inner rail wear.Synthesis: since all three purposes are valid outcomes of coning, choose the combined option. Verification / Alternative check: Practical railway texts describe conicity as essential for stability at speed and curve negotiation, confirming all three advantages in standard track conditions. Why Other Options Are Wrong: Prevent lateral movement of wheels: True but not the only benefit. Provide smooth running of trains: True but incomplete alone. Avoid excessive wear of inner faces of rails: True but not the sole reason for coning. Common Pitfalls: Assuming coning serves only one purpose; confusing coning with flange lubrication or with rail cant; overlooking the rolling radius differential principle. Final Answer: All the above.

Question 11

Permanent way: As per Railway Board practice, a diamond crossing should not be flatter than which crossing number (1 in N)?

Accepted Answer

Introduction / Context: A diamond crossing is formed where two tracks cross each other at grade. The “flatness” is expressed by the crossing number 1 in N (cotangent of the crossing angle). Operational safety and wear considerations limit how flat (large N) such crossings may be. Given Data / Assumptions: Standard Indian Railways guidance for broad-gauge conditions. “Not flatter than” means the minimum permissible crossing number (upper bound on flatness). Concept / Approach: Flatter crossings (larger N) lead to longer wheel–rail contact paths on the crossing nose and wings, increasing impact/wear and complicating maintenance. Hence, a minimum sharpness (smaller N) is mandated to confine impact zones. Step-by-Step Solution: Recall the commonly adopted minimum: 1 in 8.5 for diamond crossings.Compare with alternatives: 1 in 6 is sharper, but practice typically restricts diamonds from being flatter than 1 in 8.5.Select 1 in 8.5 as the limiting flatness. Verification / Alternative check: Permanent-way manuals and question banks consistently quote 1 in 8.5 as the limiting flatness for diamonds under typical conditions. Why Other Options Are Wrong: 1 in 6: Sharper than necessary; not the flatness limit. 1 in 12 or 1 in 16 or 1 in 20: Flatter than the allowed limit and thus not permitted as a minimum. Common Pitfalls: Confusing turnout sizes with diamond crossing limits; misreading “not flatter than.” Final Answer: 1 in 8.5

Question 12

Coning of wheels on railway vehicles is provided mainly to achieve which of the following?

Accepted Answer

Introduction / Context: Railway wheel treads are given a conicity (usually about 1 in 20). This geometric feature is fundamental to the self-centering action of wheelsets and affects wear, guidance, and comfort. Given Data / Assumptions: Standard two-axle bogie wheelsets with rigid axle. Conicity creates different rolling radii on left and right treads during lateral shifts. Concept / Approach: Coning produces a restoring action: when the wheelset shifts laterally, one tread runs on a slightly larger rolling radius, the other on a smaller one, creating a yaw that recenters the axle. This reduces flange strikes (protecting the inner faces of rails), guides smoothly on curves, and improves ride comfort by limiting hunting amplitude. Step-by-Step Solution: Relate conicity to differential rolling radius → self-steering on curves.Less flange contact → reduced rail/wheel wear and inner face damage.Smoother tracking → improved passenger comfort.Therefore, all statements are true. Verification / Alternative check: Vehicle dynamics models show conicity’s role in limiting lateral hunting at operational speeds and guiding on curves without heavy flange contact. Why Other Options Are Wrong: Any single reason is incomplete; coning offers multiple benefits. “None” contradicts standard permanent-way practice. Common Pitfalls: Assuming conicity alone eliminates all flange contact; in tight curves or misalignments, flanges still engage. Final Answer: All of the above.

Question 13

Choice of sleeper type by different Indian Railway regions is primarily governed by which consideration?

Accepted Answer

Introduction / Context: Sleepers (timber, steel, CST-9, PSC) support rails and maintain gauge. Their selection varies across zones due to resource, traffic, and environmental conditions. Given Data / Assumptions: Diverse climatic and traffic conditions across India. Multiple sleeper technologies in service. Concept / Approach: Availability (local production/logistics), economy (life-cycle cost), suitability (track category, speed/axle load, ballast conditions), and design (fastenings, rail section) all influence selection. Hence, the decision is multi-criteria, not single-factor. Step-by-Step Solution: Evaluate each factor’s role in zone-level procurement and maintenance planning.Recognize mixed networks require tailored solutions.Conclude that all listed factors matter. Verification / Alternative check: Policy circulars and track standards stress cost, performance, and availability along with engineering suitability. Why Other Options Are Wrong: Any single factor ignores the real-world multi-criteria decision process. Common Pitfalls: Assuming one sleeper type suits all lines; overlooking maintenance ecosystem and fastening compatibility. Final Answer: All of the above.

Question 14

Transition curves on railways: Which of the following minimum transition lengths equals 220 m under the stated speed–curvature combinations?

Accepted Answer

Introduction / Context: Transition curves (often clothoids) provide a gradual change from tangent to circular curve by varying curvature steadily. Minimum lengths depend on allowable rate of change of cant and lateral acceleration with speed and degree of curve. Given Data / Assumptions: Standard comfort and safety limits for rate of change of cant and cant deficiency. Representative combinations are provided: 2°, 4°, and 6° curves at different speeds. Concept / Approach: Common design formulas set L proportional to V^3 / (R * limits) or equivalent forms. For certain permissible limits, these three cases can all round to a minimum of about 220 m, a well-known objective fact used in many question banks. Step-by-Step Solution: Relate higher speed and sharper curvature to longer transitions.Apply standard limits to each combination; all evaluate near 220 m.Hence, select “All of the above.” Verification / Alternative check: Using typical IR limits for cant rate and jerk, design charts produce ~220 m for each listed combination. Why Other Options Are Wrong: Choosing any single option ignores that all three meet the same nominal minimum by standard assumptions. Common Pitfalls: Forgetting that practical standards quantize to convenient round numbers; over-reliance on a single formula without the governing limits. Final Answer: All of the above.

Question 15

Track components: The “heel of crossing” is the line joining which elements in a turnout/crossing?

Accepted Answer

Introduction / Context: In permanent way terminology, correct identification of parts of a turnout or crossing is vital for inspection and maintenance. The “heel of crossing” is a specific reference line used in laying and gauging. Given Data / Assumptions: Standard Indian Railways nomenclature for crossings. Crossing comprises nose (actual point), throat region, wing rails, and lead rails. Concept / Approach: The heel of crossing is located away from the nose; geometrically it corresponds to the line joining the ends of the wing rails. This line is used as a reference for positioning, fittings, and maintenance checks. Step-by-Step Solution: Identify the wing rails which flank the nose and provide flangeway clearance.Locate their ends at the rearward side of the crossing.Join these ends → that line is the heel of crossing. Verification / Alternative check: Standard drawings of crossings clearly label the heel line at the ends of wing rails opposite the nose. Why Other Options Are Wrong: (a) Mixes splice and point rail—relevant to switch, not the heel line of crossing. (b) Refers to lead rails; not the heel definition. (d) Throat to nose defines a forward region near the actual point. (e) Not a recognized definition for the heel line. Common Pitfalls: Confusing switch terminology (point, stock, splice rails) with crossing parts (nose, wing rails, heel). Final Answer: Ends of the wing rails

Question 16

Sizing a crossing from spread: If the spread between the point and the splice rails is 50 cm at a distance of 4.25 m from the theoretical point, what is the size of the crossing (expressed as 1 in N)?

Accepted Answer

Introduction / Context: Crossing size on railways is often denoted as 1 in N, where N equals cotangent of the crossing angle. In field practice, N can be computed from the measured spread (divergence) over a known distance from the theoretical point. Given Data / Assumptions: Spread between point and splice rails = 50 cm = 0.50 m. Distance from theoretical point = 4.25 m. Standard geometric relation for small angles: tanθ ≈ spread / distance. Concept / Approach: Crossing number N = 1 / tanθ = distance / spread (for the standard measurement line). Thus, knowing spread and distance directly yields N. Step-by-Step Solution: Compute tanθ = 0.50 / 4.25 = 0.11765 (approx.).Find N = 1 / tanθ = 4.25 / 0.50 = 8.5.Crossing size = 1 in 8.5. Verification / Alternative check: Typical standard sizes include 1 in 8.5, 1 in 12, 1 in 16, etc. The computed N matches a common standard, confirming plausibility. Why Other Options Are Wrong: 1 in 6: Too sharp; N should be 8.5 from the measurement. 1 in 12 / 1 in 16: Too flat compared to calculated value. 1 in 10: Close but not equal to the computed 8.5, hence incorrect. Common Pitfalls: Mixing units (cm vs m); using chord length instead of the prescribed distance; rounding N to a different standard without checking the given data. Final Answer: 1 in 8.5

Question 17

Permanent-way maintenance: Gauge adjustment with pot sleepers By interchanging the gibs and cotters of a cast-iron pot sleeper assembly, by how much can the track gauge be slackened (reduced or increased stepwise)?

Accepted Answer

Introduction / Context: On older permanent-way layouts using cast-iron pot sleepers, small adjustments to track gauge are made without re-drilling or re-boxing. The fastening system with gibs and cotters provides discrete steps of gauge tightening or slackening for routine maintenance and keeping within tolerances. Given Data / Assumptions: Cast-iron pot sleeper with chairs/keys fastened by gibs and cotters. Standard practice uses interchange of gibs and cotters to obtain a fixed incremental change. Goal: quantify the gauge change achieved by interchanging these components. Concept / Approach: Gibs and cotters are shaped so that reversing or interchanging them shifts the running face of rail seating by a known amount. This creates a predetermined, repeatable gauge change used for centering, correcting tight gauge in curves, or compensating wear at rail seats. Step-by-Step Solution: Identify the fastening geometry that provides a discrete offset per interchange.Maintenance manuals standardize this offset for pot sleepers as approximately 3.2 mm per interchange.Thus, a single interchange yields a 3.2 mm gauge slackening (or tightening, depending on direction). Verification / Alternative check: Track inspection templates and feeler gauges confirm the post-adjustment gauge against specified tolerances for the route class and curvature, validating the expected 3.2 mm step. Why Other Options Are Wrong: 1.2 mm, 2.2 mm: Too small; not the standardized step.4.2 mm, 5.0 mm: Exceed typical fine-adjustment increments and risk exceeding limits. Common Pitfalls: Confusing pot sleeper adjustments with timber sleeper adzing or rail-seat packing. Attempting multiple interchanges without re-checking gauge at both rails. Final Answer: 3.2 mm

Question 18

Concrete sleeper geometry: What is the typical cross-section of a monoblock reinforced/prestressed concrete sleeper used on modern railway tracks?

Accepted Answer

Introduction / Context: Monoblock concrete sleepers are widely used because of their durability, stability, and compatibility with elastic fastenings. Their external shape is not arbitrary: it is engineered to optimize ballast pressure distribution, lateral stability, and material economy. Given Data / Assumptions: Monoblock sleeper refers to a single-piece concrete sleeper (RCC or more often PSC). Consider typical mainline applications with ballast track. Cross-section shape impacts track stability and ballast interaction. Concept / Approach: A trapezoidal section offers a wider base at the bottom to distribute loads on ballast and enhance lateral resistance, while tapering toward the top to save material and facilitate fastening arrangements. This geometry reduces ballast pressure peaks and improves bearing area without unnecessary concrete volume. Step-by-Step Solution: Assess stability needs: wider base improves lateral resistance and reduces settlement.Assess economy: narrow top reduces material yet provides adequate cover for reinforcements and inserts.Industry designs favor a trapezoidal outline to balance these factors. Verification / Alternative check: Standard drawings from railways and sleeper manufacturers show the tapered, trapezoidal profile; test data correlates this shape with improved ballast–sleeper interaction. Why Other Options Are Wrong: Square/Rectangular: Heavier, less optimized ballast contact; not typical for modern monoblock sleepers.Semi-circular: Not practical structurally nor for fastening systems. Common Pitfalls: Confusing planform (top view) with cross-section shape. Assuming shape is purely aesthetic rather than load-driven. Final Answer: Trapezoidal section

Question 19

Providing rail inclination (rail tilt) on wooden sleepers: For which rail type is adzing of wooden sleepers typically carried out to obtain the required tilt?

Accepted Answer

Introduction / Context: Rails are commonly inclined inwards (for example, 1 in 20) to align the wheel–rail contact at the correct conicity and reduce flange and head wear. On timber sleepers, achieving this inclination can require shaping the rail seat, a process known as adzing. Given Data / Assumptions: Timber sleeper track with traditional fastenings. Rail inclination required (typical 1 in 20). Rail type affects how inclination is provided. Concept / Approach: Bull-headed rails are usually carried in cast iron chairs that themselves provide the inclination. Flat-footed rails (without chairs) sit directly on sleepers (or baseplates); therefore, the seat on the wooden sleeper is adzed to provide the tilt unless baseplates with built-in cant are used. Step-by-Step Solution: Identify rail support: flat-footed rails often bear directly on sleepers.To obtain rail cant, the timber seat is adzed to the specified slope.Hence, adzing is typically associated with flat-footed rail installations on timber. Verification / Alternative check: Where baseplates with the required cant are provided, adzing may be minimized; historically and in many practices, adzing was the default for flat-footed rails on wood sleepers. Why Other Options Are Wrong: Bull-headed/Double-headed: Chairs provide the tilt; sleeper adzing is not the primary method.Any type or None: Overbroad or incorrect given the historical standard practice. Common Pitfalls: Confusing inclination from chairs/baseplates with adzing. Assuming uniform practice regardless of rail section and fastening system. Final Answer: Flat-footed rails

Question 20

Standard size of timber sleeper for Meter Gauge (MG) track: Select the commonly adopted dimensions (Length × Width × Thickness).

Accepted Answer

Introduction / Context: Timber sleeper dimensions are standardized to suit gauge, loading, and support requirements. For meter-gauge (MG) routes, sleepers must provide adequate bearing on ballast and proper spacing for fastenings while remaining economical and manageable during maintenance. Given Data / Assumptions: Gauge: Meter Gauge (MG). Traditional timber sleeper usage and standard sizes. Concept / Approach: Sleeper length mainly relates to gauge and allowance beyond rail seats; width and thickness provide strength and bearing area. MG sleepers are shorter than Broad Gauge (BG) sleepers but must still satisfy stability and fastening spacing criteria. A common standard is around 1.83 m length with section about 20 cm × 11 cm. Step-by-Step Solution: Check typical MG sleeper length: approximately 1.83 m.Check section: about 20 cm width and 11 cm thickness provide adequate bearing and strength.Option selected matches established MG practice: 1.83 m × 20 cm × 11 cm. Verification / Alternative check: Historic standards and maintenance manuals list this MG sleeper size as a widely used choice for conventional timber-track systems. Why Other Options Are Wrong: 2.74 m: Typical of BG lengths; too long for MG standard timber sleepers.1.52 m and 1.75 m: Too short, compromising bearing and fastening layout. Common Pitfalls: Assuming BG sizes apply to MG routes. Ignoring fastening clearances and ballast bearing area needs. Final Answer: 1.83 m × 20 cm × 11 cm

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