Question 1

Turnout geometry: The overall length of a turnout is measured from the end of the stock rail up to which reference point in the crossing?

Accepted Answer

Introduction / Context: A turnout diverts trains from the main line to a diverging route using a switch (stock and tongue rails) and a crossing (frog). Understanding standard measurement points is essential for layout planning, material ordering, and site setting out. Given Data / Assumptions: Overall turnout length definition is sought. Reference features include stock rail end, toe of switch, throat, actual nose, and heel of crossing. Concept / Approach: Railway practice defines the overall length of a turnout from the end of stock rail (at the switch end) to the heel of crossing—the point where the wing and crossing rails effectively complete the diverging geometry before the straight lead away. Step-by-Step Solution: Identify starting reference: end of stock rail at the switch.Identify terminal reference: heel of the crossing, not the actual nose.Hence, overall length = distance between these two points. Verification / Alternative check: Standard turnout drawings and tables list overall lengths tabulated to the heel, matching site measurement practice for ballastless and ballasted tracks alike. Why Other Options Are Wrong: Actual nose/throat: Intermediate points used for checking geometry; not the terminal for overall length definition.Toe of crossing: Not the standard endpoint for total turnout length. Common Pitfalls: Confusing nose of crossing (critical for wheel guidance) with heel position used in length definitions. Using switch toe-to-nose dimension instead of full turnout length. Final Answer: Heel of crossing

Question 2

Service life of timber sleepers: Which factors primarily govern the life of a wooden sleeper in track?

Accepted Answer

Introduction / Context: Wooden sleepers remain in service in many networks for sidings and low-density lines. Their service life varies widely due to material properties and environment. Understanding the key determinants aids procurement and maintenance planning. Given Data / Assumptions: Sleeper life is influenced by both inherent wood characteristics and external conditions. Proper treatment (creosote/CCA) and drainage practices assumed to be standard. Concept / Approach: Durable species with good density and strength resist crushing and splitting. Preservative treatment and seasoning combat fungi and insects. Exposure to moisture cycles, UV radiation, and temperature affects checking and decay; ballast drainage and maintenance mitigate these effects. Step-by-Step Solution: Quality: Strong, defect-free timber better resists mechanical stresses from traffic.Decay resistance: Proper preservative treatment substantially increases life.Weathering resistance: Good detailing and ballast drainage reduce wet–dry cycles and rot. Verification / Alternative check: Field records show large life variability (often 7–25 years) depending on the three factors; improved treatment and drainage correlate with longer life. Why Other Options Are Wrong: No single factor can guarantee life; the combined influence is decisive, hence “All of the above”. Common Pitfalls: Focusing only on species and ignoring preservative treatment quality. Neglecting drainage, leading to premature rot despite good timber. Final Answer: All of the above

Question 3

Track laying practices in India: Which method is most commonly used by Indian Railways for plate laying on new lines or renewals?

Accepted Answer

Introduction / Context: Plate laying—placing sleepers and rails progressively to construct track—can be executed by different methods. Indian Railways has evolved practices considering logistics, resource availability, and the need to maintain alignment and level during construction. Given Data / Assumptions: Comparison of common methods: side, telescopic, and American. Focus: method typically adopted in India for general work. Concept / Approach: In the telescopic method, panels are laid out progressively from an existing railhead, extending the track in a stepwise manner. It enables efficient use of materials brought to railhead, good control of alignment/level, and steady advance without excessive preliminary distribution. Step-by-Step Solution: Assess logistics: telescopic method minimizes double handling.Assess quality control: progressive alignment checks are easier.Indian Railways widely prefers the telescopic method for standard projects. Verification / Alternative check: Standard codes of practice and manuals describe telescopic laying as the usual approach, with side method used in constrained conditions and American method in specialized mechanized contexts. Why Other Options Are Wrong: Side method: Material is stacked along the alignment beforehand; less efficient for long advances.American method: Machinery-intensive; not the default across Indian projects.All of the above: Overbroad; one is most common—telescopic. Common Pitfalls: Assuming one method suits all terrains; site constraints can dictate alternatives. Ignoring safety while advancing the railhead. Final Answer: Telescopic method

Question 4

Composite Sleeper Index (CSI): What does this index primarily indicate in sleeper selection and procurement?

Accepted Answer

Introduction / Context: Timber sleepers vary in species, density, strength, and durability. The Composite Sleeper Index (CSI) combines multiple attributes into a single figure to assess and compare the suitability of wooden sleepers for track service. Given Data / Assumptions: CSI aggregates mechanical and durability characteristics. Used by railways to evaluate timber sleeper options for procurement. Concept / Approach: CSI is a weighted index derived from parameters such as specific gravity, modulus of elasticity, crushing strength, and resistance to decay/borers. A higher CSI generally correlates with longer expected service life and better performance under traffic loads and environmental exposure. Step-by-Step Solution: Identify performance drivers: strength, stiffness, durability.Combine into an index to rank timber types objectively.Use CSI threshold values to approve or reject sleeper lots. Verification / Alternative check: Procurement specifications often stipulate minimum CSI and preservative treatment standards. Field performance audits validate that higher CSI timbers perform better in track. Why Other Options Are Wrong: Number of sleepers per rail length: Determined by sleeper density policy, not CSI.Permissible stresses in steel sleepers: Material-specific design data, unrelated to CSI for timber. Common Pitfalls: Treating CSI as a sole criterion while ignoring treatment quality and seasoning. Using CSI values without considering route class and traffic density. Final Answer: Suitability of wooden sleepers (quality assessment for service)

Question 5

Limits on unbalanced speed: What is the maximum cant deficiency generally prescribed on Indian Broad Gauge (BG) railways?

Accepted Answer

Introduction / Context: Cant deficiency is the shortfall of provided cant relative to the equilibrium cant needed at a given speed and curve radius. Allowing some cant deficiency enables higher speeds without fully matching equilibrium cant, balancing comfort, safety, and track maintenance needs. Given Data / Assumptions: Route class and vehicle characteristics follow Indian BG standards. We consider typical limits used in mainline operations, not exceptional trials. Concept / Approach: Passenger comfort and lateral force limits determine the permissible unbalanced lateral acceleration, translating to a cant deficiency cap. For Indian BG, a commonly adopted maximum cant deficiency is approximately 75 mm for general operations, subject to vehicle dynamics and route approvals. Step-by-Step Solution: Relate cant deficiency to unbalanced lateral acceleration perceived by passengers.Adopt network-standard cap balancing speed potential and safety.Hence, choose 75 mm as the typical maximum for BG. Verification / Alternative check: Vehicle-Track Interaction guidelines and IR codes cite around 75 mm (context-dependent) as the normative maximum, with special cases requiring specific sanction and checks. Why Other Options Are Wrong: 25–50 mm: Too conservative for most BG mainline standards.100 mm: Exceeds normal comfort/safety envelopes without special sanction. Common Pitfalls: Confusing cant deficiency with cant excess (over-cant at low speeds). Applying metro/suburban limits directly to intercity BG contexts. Final Answer: 75 mm

Question 6

Switch geometry on BG tracks: Recommended heel divergence (distance between the running face of stock rail and gauge face of tongue rail at the heel) for Indian Broad Gauge is closest to which value?

Accepted Answer

Introduction / Context: Heel divergence is a key geometric parameter of a switch, affecting wheel guidance, fit-up, and compatibility with standard turnout components. Indian BG standards specify a nominal divergence at the heel to ensure interchangeability and safe operation. Given Data / Assumptions: Standard BG turnouts (e.g., 1 in 8.5, 1 in 12) with standardized switch assemblies. Looking for typical recommended heel divergence dimension. Concept / Approach: Heel divergence is defined at the heel where the tongue rail ends and is connected to the switch rail via heel block/fastenings. The dimension is chosen to balance smooth entry, avoid excessive flangeway variation, and fit standard bearers and fittings. A common standard value is approximately 125 mm for Indian BG practice. Step-by-Step Solution: Identify the standard heel divergence used across BG switches.Confirm compatibility with standard bearers and switch plates.Select 125 mm as the recommended nominal value. Verification / Alternative check: Standard drawings for BG switches indicate heel divergence in this range, ensuring consistent fit and wheel guidance across turnout types. Why Other Options Are Wrong: 100 mm, 119 mm: Below typical standard; may compromise fit and flangeway.135 mm, 155 mm: Larger than standard and could affect wheel guidance and component compatibility. Common Pitfalls: Confusing heel divergence with switch opening at the toe. Using non-standard values that hinder interchangeability of components. Final Answer: 125 mm

Question 7

Permanent way – switch selection: For achieving the best operational performance and reduced maintenance at turnouts, which type of switch is generally preferred on modern railway track?

Accepted Answer

Introduction / Context: Turnouts are critical assemblies in railway permanent way. The design of the switch (tongue rail against stock rail) strongly influences ride quality, impact forces, wear, and maintenance needs. Among historical forms—straight-cut, undercut, and overriding—modern practice standardizes the geometry to minimize wheel impacts and provide smooth entry to the diverging route. Given Data / Assumptions: Mainline turnouts on standard modern track. Objective is best performance: smooth guidance, reduced impact/wear, better service life. Correct chairing, fastening, and rail profile assumed. Concept / Approach: An undercut switch is planed on the underside of the tongue head/web, allowing the top running surface of the tongue to remain flush with the stock rail running face when closed. This creates a near-continuous running surface, reduces the wheel flange contact shock, and improves both safety and service life. Straight-cut and especially overriding forms lead to higher impact and wear at the switch toe. Step-by-Step Solution: 1) Performance goal: minimize wheel-rail impact at the switch interface.2) Compare switch types: straight-cut vs undercut vs overriding.3) Undercut retains flush top running, reducing impact and promoting smooth guidance.4) Conclude undercut switch is preferred for best overall performance. Verification / Alternative check: Track standards and maintenance reports consistently show reduced battering at the tongue toe, lower wear rates, and improved geometry retention with undercut switches compared with older straight-cut or overriding designs. Why Other Options Are Wrong: Straight-cut switch: simpler but causes more impact at the toe. Overriding switch: increased risk of topping and surface mismatch. Both (a) and (b) / None: only the undercut form aligns with the stated performance objective. Common Pitfalls: Confusing switch type (undercut) with switch plan geometry (straight vs curved switch—another concept). Ignoring correct planing and maintenance, which are essential even for undercut switches. Final Answer: Undercut switch.

Question 8

Railway yard layout: A “triangle” (wye) for turning locomotives is composed of which set of turnout elements?

Accepted Answer

Introduction / Context: In railway yards, turning a locomotive through 180 degrees can be accomplished by a turntable or a triangular layout called a “wye”. Understanding its composition helps in planning yard space, budgeting, and maintenance strategies. Given Data / Assumptions: Standard broad-gauge or standard-gauge yard practice. Triangle intended for reversing locomotive orientation. No turntable available; trackwork used instead. Concept / Approach: A wye consists of three legs arranged roughly as an equilateral triangle’s sides, each leg connected by a turnout. By shunting the locomotive around the triangle, it emerges facing the opposite direction without lifting or rotating it vertically (as a turntable would do). Step-by-Step Solution: 1) Identify the number of junctions needed to form three connected legs.2) Each junction requires one turnout to diverge toward the next leg.3) Therefore, three legs imply three turnouts.4) This minimal arrangement allows full reversal by successive movements. Verification / Alternative check: Practical yard designs confirm three turnouts are sufficient; additional slips or crossovers are not essential for the basic function of turning. Why Other Options Are Wrong: Turnout/split/slip combinations listed do not represent the minimal, standard wye configuration. Common Pitfalls: Confusing “slips” (double or single slips) and “splits” with turnouts; slips are compact special trackwork items mainly for dense junctions, not for simple wyes. Final Answer: Three turnouts.

Question 9

Permanent way detail: What rail top inclination (cant) is provided on the seating of steel sleepers to match the rail's standard inward cant?

Accepted Answer

Introduction / Context: Rails are commonly installed with a small inward inclination (cant) so that the rail head aligns optimally with wheel conicity, reducing flange and tread wear. Sleeper seats are therefore prepared to provide this cant consistently along the track. Given Data / Assumptions: Standard track with coned wheel treads. Steel sleepers with machined or formed rail seats. Standard rail cant practice adopted. Concept / Approach: The conventional rail cant is 1 in 20 inward, meaning the rail top is tilted toward the track centerline. Steel sleeper seats mirror this cant to ensure the rail head presents the correct angle to approaching wheels, improving stability, reducing wear, and enhancing riding comfort. Step-by-Step Solution: 1) Identify standard rail cant = 1 in 20 inward.2) Provide matching cant on steel sleeper seats.3) This maintains uniform geometry and wheel-rail contact conditions. Verification / Alternative check: Design drawings and track standards specify a 1 in 20 inward inclination for most mainline track; timber, concrete, and steel sleepers are all configured accordingly. Why Other Options Are Wrong: No cant or outward cant misaligns the rail-wheel interface and increases wear. 1 in 40 cant is not the standard value for modern mainline practice. Common Pitfalls: Assuming concrete sleepers alone provide cant; all sleeper types must match the specification. Final Answer: Inward cant of 1 in 20.

Question 10

Track maintenance access: What is the minimum packing (tamping) space typically provided between two sleepers to allow effective maintenance?

Accepted Answer

Introduction / Context: Efficient tamping of ballast under sleepers requires adequate lateral space between adjacent sleepers for inserting tamping tools (manual or machine tines). Too little spacing hampers compaction quality; too much reduces sleeper density and track stiffness. Given Data / Assumptions: Mainline track with standard sleeper dimensions. Manual or mechanized tamping operations. Ballast depth and crib dimensions are within standard practice. Concept / Approach: The packing space (crib width) must allow tools to penetrate and compact ballast effectively. A commonly adopted minimum is about 30 to 35 cm. This balances maintainability with sleeper spacing needed for structural support and load distribution. Step-by-Step Solution: 1) Identify maintenance requirement: tool/tine insertion and manipulation.2) Provide crib width ~30–35 cm to meet this need.3) Ensure uniformity along the track to maintain consistent support conditions. Verification / Alternative check: Track handbooks and mechanized maintenance guidelines adopt crib widths near 30–35 cm for effective tamping and drainage while maintaining sleeper density for stiffness. Why Other Options Are Wrong: 20–30 cm: often too tight for efficient tamping, especially mechanized tines. 35–40 cm or more: reduces sleeper density for a given rail seat loading unless spacing is redesigned. Common Pitfalls: Cramming ballast without leaving sufficient crib width—leads to poor compaction and voids. Non-uniform crib widths causing differential settlement. Final Answer: 30 to 35 cm.

Question 11

Ballast material selection: The ballast packed under and around sleepers to transfer loads to the formation commonly consists of which materials?

Accepted Answer

Introduction / Context: Ballast provides load distribution, drainage, and track resilience. Selection depends on availability, cost, and performance. While broken stone is preferred for main lines, gravel and moorum can be used in lower category lines or as sub-ballast and shoulders. Given Data / Assumptions: Conventional ballasted track structure. Requirement for drainage, interlock, and resilience. Regional material availability considered. Concept / Approach: Broken stones (angular) interlock well and provide superior stability and drainage. Gravels can function where stone is scarce. Moorum (weathered lateritic material) is sometimes used as sub-ballast or in yards with low speeds. Hence, multiple materials may be adopted depending on service conditions. Step-by-Step Solution: 1) Identify performance needs: strength, drainage, maintainability.2) Evaluate material properties: angularity, durability, permeability.3) Conclude that broken stone, gravel, and moorum are all used in practice, with broken stone preferred for high-speed/mainline. Verification / Alternative check: Maintenance manuals specify preferred gradations for stone ballast and acceptable substitutes for lower classes of track. Why Other Options Are Wrong: Cement mortar is not a ballast; it would create rigid support and block drainage. Common Pitfalls: Using rounded river pebbles without adequate angularity leads to poor interlock. Ignoring proper gradation and fouling control causes drainage issues. Final Answer: All of the above.

Question 12

Switch rail form for modern track: Which type of switch rail is generally adopted on contemporary mainline track to improve alignment and riding quality through turnouts?

Accepted Answer

Introduction / Context: Modern turnouts aim to provide higher permissible speeds and smoother guidance into the diverging route. The planform of the switch rail—straight versus curved—affects entry alignment and impact forces at the switch toe. Given Data / Assumptions: Mainline or high-class track turnouts. Objective: improved ride and lower maintenance. Compatible crossing and lead design. Concept / Approach: Curved switches provide a gradual change in curvature, aligning better with turnout geometry and reducing sudden steering demand on wheelsets. This yields smoother transitions, less battering, and improved service life compared to straight switches in the same lead length. Step-by-Step Solution: 1) Identify governing objective: smoother diverging entry.2) Compare planforms: straight vs curved switch.3) Curved switch offers progressive curvature → reduced impact and wear. Verification / Alternative check: Track design guides and field experience show higher diverging speeds and reduced maintenance with curved switches for equivalent sizes (e.g., 1 in 12, 1 in 16). Why Other Options Are Wrong: Straight switch: sharper entry, higher impacts. Loose-heel/bent/stub: outdated or special-purpose forms not typical for modern main lines. Common Pitfalls: Confusing undercut vs curved—undercut is a planing detail, curved is a geometric planform. Final Answer: Curved switch.

Question 13

Track geometry term: The “gauge” of a permanent way is defined as which distance relative to the rails?

Accepted Answer

Introduction / Context: Gauge is a fundamental dimension of track; it defines compatibility with rolling stock and directly affects stability and capacity. The precise definition ensures consistent wheel-rail guidance across the network. Given Data / Assumptions: Two parallel rails forming a track. Running faces are the inner faces contacted by wheel flanges. Measurement taken at a specified distance below the rail top per standards. Concept / Approach: Gauge is specified as the minimum distance between the running faces of the two rails. Measuring between running faces captures the actual guidance clearance for wheel flanges, unlike centre-to-centre or outer-face dimensions which vary with rail section and wear. Step-by-Step Solution: 1) Identify the functional faces guiding the wheels: the running (inner) faces.2) Define gauge as the minimum spacing between these faces.3) Ensure measurements follow standard height from rail top to avoid head profile effects. Verification / Alternative check: All major standards (broad/standard/metre gauge) define gauge using running faces, confirming the correct option. Why Other Options Are Wrong: Outer faces or centre lines do not dictate flange guidance. Formation width is unrelated to rail gauge. Common Pitfalls: Measuring at the rail head top corner instead of prescribed datum below top where profile is stable. Final Answer: Minimum distance between running faces of the two rails.

Question 14

Transition curves – length limit by cant deficiency: If S is the cant deficiency in centimetres and V is the maximum permissible speed in km/h, what is the recommended maximum length L of the transition curve (in metres)?

Accepted Answer

Introduction / Context: Transition curves provide a gradual change from straight track to circular curvature, controlling the rate of change of cant and cant deficiency for passenger comfort and safety. Standards limit the allowable rate of cant (and cant deficiency) change, which governs the minimum/maximum transition length. Given Data / Assumptions: Cant deficiency S is given in centimetres. Speed V is in kilometres per hour. We seek a practical expression for maximum transition length constrained by the rate of change of cant deficiency. Concept / Approach: Common railway practice gives the relation L = 0.008 * V * S when S is in millimetres. Since 1 cm = 10 mm, substituting S(cm)*10 for S(mm) yields L = 0.008 * V * 10 * S(cm) = 0.08 * V * S(cm). This provides L in metres when V is in km/h and S in cm. Step-by-Step Solution: 1) Start with standard: L = 0.008 * V * S(mm).2) Convert S(cm) to S(mm): S(mm) = 10 * S(cm).3) Substitute: L = 0.008 * V * (10 * S) = 0.08 * V * S.4) Units: V in km/h, S in cm → L in metres. Verification / Alternative check: The expression aligns with comfort-based cant gradient limits and is widely used as a quick design check before detailed alignment computations. Why Other Options Are Wrong: 0.008 * V * S: correct only if S is in millimetres, not centimetres. 0.8 * V * S and 0.028 * V * S: produce unrealistically long or short transitions. 0.8 * S / V: incorrect dependence on speed. Common Pitfalls: Mixing units (mm vs cm) leading to order-of-magnitude errors. Ignoring other constraints such as available length between point of curvature and point of switch. Final Answer: L = 0.08 * V * S.

Question 15

Special sleepers on curves: Cast iron “pot” sleepers are suitable only up to what maximum degree of curve?

Accepted Answer

Introduction / Context: Pot sleepers (special cast iron units) were historically used in certain yards and low-speed track. Their suitability on curves is limited due to geometry and fastening constraints. Knowing the limit helps prevent excessive gauge widening and fastener stress. Given Data / Assumptions: Legacy or secondary track applications for pot sleepers. Degree of curve is used as curvature measure (degree = angle subtended by a 30.5 m chord in some systems; conceptually, higher degree means tighter curve). Acceptable lateral forces and flange clearances assumed. Concept / Approach: Due to their geometry, pot sleepers provide limited ability to accommodate sharp curvature without overstressing fittings or compromising gauge and cant. Hence, a conservative cap on their use is set at about 4° to ensure safe wheel guidance and manageable maintenance. Step-by-Step Solution: 1) Recognize limitations of pot sleeper assemblies on sharp curves.2) Apply the customary limit adopted in practice: ≤ 4°.3) Beyond this, adopt more suitable sleeper/fastening systems (e.g., concrete or timber with elastic fastenings). Verification / Alternative check: Legacy track standards restricted pot sleepers on sharper curves due to maintenance and safety issues, confirming 4° as a practical upper bound. Why Other Options Are Wrong: Values above 4° allow too tight curvature for the pot sleeper arrangement under typical service conditions. Common Pitfalls: Using pot sleepers on mainline curves with higher speeds or heavy axle loads—leads to rapid deterioration. Final Answer: 4°.

Question 16

Geometry of parallel sidings: If D is the distance between two parallel sidings and α is the angle of crossing, what is the distance measured along the gathering line between the noses of crossing?

Accepted Answer

Introduction / Context: In yard and siding layout, crossing geometry determines the longitudinal spacing required to transition between parallel tracks. The distance between noses of crossing along the gathering line directly affects land take and layout length. Given Data / Assumptions: Two parallel sidings separated by distance D. Angle of crossing with respect to the track axis is α. Gathering (lead) line is aligned at angle α to the parallel tracks. Concept / Approach: Resolving the perpendicular separation D along a line inclined at angle α, the required length along the gathering line equals the component of the perpendicular distance when projected along the inclined line. Trigonometry gives length = D / tan α = D cot α. Step-by-Step Solution: 1) Represent the two parallel tracks with perpendicular separation D.2) The gathering line makes angle α with the tracks.3) Distance along gathering line to span D: L = D / tan α = D cot α. Verification / Alternative check: Check limiting cases: for small α (shallow crossing), tan α is small and cot α large, hence L becomes large—consistent with practice where flatter crossings need longer leads. Why Other Options Are Wrong: D tan α or D sin α or D cos α give incorrect projections for this geometry. D / tan α is algebraically the same as D cot α; the accepted concise form is D cot α. Common Pitfalls: Confusing α as the turnout angle at the switch instead of the crossing angle; in layout calculations, be consistent with defined angles. Final Answer: D cot α.

Question 17

In Indian Railway track design for timber sleepers: if S is the strength index and H is the hardness index of the timber (both evaluated at 12% moisture content), what is the composite sleeper index (CSI) used for suitability comparison?

Accepted Answer

Introduction / Context: The composite sleeper index (CSI) is a simple, widely cited metric in railway engineering for comparing different timber species for sleepers. It combines two essential material characteristics—strength and hardness—measured at a standardized 12% moisture content to reflect field conditions for track components. Given Data / Assumptions: S = strength index of the timber at 12% moisture content. H = hardness index of the timber at 12% moisture content. Both indices are dimensionless comparative measures derived from standard tests. Concept / Approach: Sleepers demand adequate bending strength to resist rail-seat loads and sufficient hardness to withstand crushing and wear from fastenings and rail bearing. A composite index that multiplies these factors reflects that a poor value in either strength or hardness significantly degrades overall performance; hence a product (not a sum) better captures combined adequacy. Step-by-Step Solution: Define CSI based on combined strength and hardness performance.Adopt the multiplicative formulation to penalize low values in either parameter.Therefore, CSI = S × H. Verification / Alternative check: For two timbers: Timber A (S=100, H=70) vs Timber B (S=85, H=85). Although sums are equal (170), product favors the more balanced timber: 100×70 = 7000 vs 85×85 = 7225, aligning with engineering intuition that balance is desirable. Why Other Options Are Wrong: CSI = S + H ignores interaction; (S × H)/100 is merely a scaled form without standard practice; S/H or 2S + H distort relative influence and provide no accepted engineering basis. Common Pitfalls: Using indices at moisture levels other than 12% or mixing test standards; comparing species without accounting for preservative treatability and service conditions. Final Answer: CSI = S × H

Question 18

In permanent-way terminology, a scissors crossover comprises one diamond crossing together with how many turnouts?

Accepted Answer

Introduction / Context: A scissors crossover is a compact track arrangement used where space is limited but operational flexibility is required. It allows trains to cross from one track to the other in either direction within a short length, commonly found in station throats and busy junction approaches. Given Data / Assumptions: Definition focuses on the constituent special trackwork elements. Diamond crossing provides the physical track intersection. Turnouts provide the route divergence for crossovers. Concept / Approach: A scissors crossover is essentially two crossovers overlapped: one left-hand and one right-hand, interlaced through a diamond crossing. Each crossover requires two turnouts. Therefore, two crossovers together require four turnouts, plus the single diamond where the running rails intersect. Step-by-Step Solution: Recognize that a basic crossover = 2 turnouts.A scissors crossover = 2 crossovers superimposed = 2 × 2 turnouts = 4 turnouts.One diamond crossing connects the interlaced routes. Verification / Alternative check: Standard plan drawings show four sets of switch-tongue/stock-rail assemblies for the two opposing movements, in addition to the central diamond. Why Other Options Are Wrong: One, two, or three turnouts cannot form both crossovers; “no turnout” is incorrect since switches are essential for route setting. Common Pitfalls: Confusing a scissors crossover with a simple diamond (no routing choice) or with a single crossover (only one direction of transfer). Final Answer: Four turnouts

Question 19

In turnout construction, what are stock rails and where are they fitted within the switch assembly?

Accepted Answer

Introduction / Context: Turnouts enable a train to leave the main line to a diverging route. The switch assembly consists of stock rails and tongue (switch) rails that create the variable pathway. Understanding these components is fundamental to track design, maintenance, and safety inspections. Given Data / Assumptions: Focus is on the identification and function of stock rails. Standard broad-gauge practice with conventional flat-footed rails. Concept / Approach: The stock rail is the running rail against which the tapered tongue rail fits tightly when the route is set. The stock rail provides a continuous guiding surface; the tongue rail moves to contact the stock rail on either side to select the route (main or diverging). Step-by-Step Solution: Identify static member: stock rail.Identify movable member: tongue (switch) rail.Correct relation: stock rail is fitted against (in contact with) the tongue rail when set. Verification / Alternative check: Inspection manuals specify gauge and contact requirements between stock and tongue rails to avoid wheel-flange picking and ensure safe route selection. Why Other Options Are Wrong: (a) Crossing parts are separate assemblies; (b) check rails are used near crossings to control flange path, not in the switch contact; (d) stock rail extends beyond those limits; (e) expansion joints are different assemblies. Common Pitfalls: Confusing check-rail function with stock rail; assuming stock rails are interchangeable with common rails without specific planing for switch fit. Final Answer: Fitted against the tongue (switch) rails

Question 20

On Broad Gauge (B.G.) tracks of Indian Railways, the standard grade compensation for curvature is taken as

Accepted Answer

Introduction / Context: On curves, additional resistance acts on trains due to flange and alignment effects. To maintain equivalent tractive effort, railways reduce the ruling gradient on curves—a practice called grade compensation. Values differ by gauge and administration; Indian standards adopt conventional fixed percentages. Given Data / Assumptions: Gauge: Broad Gauge (B.G.). Typical Indian Railways practice for main-line design. Compensation is a fixed percentage per degree of curve applied to the ruling gradient. Concept / Approach: Grade compensation offsets curve resistance so that locomotives face similar total resistance on curves as on straight reaches. For B.G., a widely used standard figure is 0.04% per degree of curve, applied to the gradient, limited so as not to over-flatten grades excessively. Step-by-Step Solution: Identify gauge-specific practice: B.G. → 0.04% per degree.Apply to gradient design as required by curve degree.Select the option matching 0.04%. Verification / Alternative check: Design manuals and standard textbooks list 0.04% for B.G., with different values for other gauges (e.g., M.G. often 0.03%). Why Other Options Are Wrong: Other values do not reflect the standard B.G. practice; 0.05% or 0.06% would overcompensate, while 0.02–0.03% undercompensate for B.G. Common Pitfalls: Confusing grade compensation per degree with superelevation; applying compensation without checking maximum limits specified for particular routes. Final Answer: 0.04%

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