Question 1

Permanent-way practice: For inspection and packing of ballast around cast-iron pot sleepers, how many packing holes are provided in each pot sleeper?

Accepted Answer

Introduction / Context: In traditional Indian permanent-way practice, cast-iron pot sleepers were widely used. For maintenance (tamping/packing of ballast) and quick inspection, specific openings are cast into the sleeper. Knowing the number and purpose of these holes is a basic track-maintenance competency. Given Data / Assumptions: Sleepers are pot-type cast-iron units. Maintenance requires periodic packing/tamping of ballast beneath rail seats. Openings in the sleeper are dedicated to packing and visual checking. Concept / Approach: Pot sleepers are designed with packing holes to let tools reach the ballast and to allow easy inspection of its condition. Too few holes would hinder maintenance; too many would weaken the casting and add cost. Standard CI pot sleepers therefore adopt two holes balanced around the rail seat region to facilitate packing. Step-by-Step Solution: Confirm the sleeper type: cast-iron pot sleeper.Relate maintenance need: packing tools must access ballast effectively.Design choice: provide two packing/inspection holes per sleeper for adequate access without compromising strength. Verification / Alternative check: Practice manuals and legacy drawings show two circular openings in a typical CI pot sleeper precisely for ballast packing and inspection access. Why Other Options Are Wrong: One hole: inadequate access for uniform packing. Three or four holes: unnecessary and may weaken the casting or complicate manufacture. None of these: contradicts standard practice. Common Pitfalls: Confusing pot sleepers with plate or box sleepers, which have different shapes and features. Final Answer: Two holes.

Question 2

Turnout geometry: In a diamond crossing (two tracks intersecting), how many noses of crossing are present?

Accepted Answer

Introduction / Context: A diamond crossing is the arrangement where two tracks cross each other without connecting turnouts. Understanding its components—especially the number of noses (actual crossing points)—is foundational for track-layout design and maintenance. Given Data / Assumptions: Standard diamond with two straight tracks crossing. Each actual crossing has a nose (the point where running edge changes). Concept / Approach: A diamond consists of two acute-angle crossings arranged opposite each other, which together form four noses: one at each quadrant of the intersection where a running edge converges to a point. Step-by-Step Solution: Visualize the X-shaped intersection of two rails.Identify each actual crossing (V-shape) and its nose.Count all noses in the complete diamond: total is 4. Verification / Alternative check: Standard drawings of diamonds show four noses accompanied by check rails guiding flanges through the crossing gaps. Why Other Options Are Wrong: 2 or 3: undercounts the required crossing points. 6: overcounts; typical diamond geometry has four noses. Common Pitfalls: Confusing the number of noses with the number of check rails or wing rails. Final Answer: 4.

Question 3

Sleeper design basics: What is the typical effective bearing area (contact area with ballast/formation) considered for sleepers in design calculations?

Accepted Answer

Introduction / Context: The effective bearing area of sleepers is used in stress calculations on formation and in deciding ballast depth/quality. A representative value aids in load-spreading estimates and serviceability checks for the track structure. Given Data / Assumptions: Conventional sleeper sizes (timber, CI, PSC) with standard seating on ballast. Design adopts an effective area that reflects real contact (less than gross plan area). Concept / Approach: Because ballast interlock and sleeper underside are not perfectly planar, the entire underside does not bear uniformly. A practical, conservative effective bearing area is adopted in design. Traditionally, 0.42 m^2 is widely used for calculations, aligning with empirical performance. Step-by-Step Solution: Select a standard effective area consistent with codes and experience.Use this area in bearing pressure and settlement checks.Adopt 0.42 m^2 as the representative value. Verification / Alternative check: Handbooks commonly quote 0.42 m^2 as a benchmark, with local adjustments based on sleeper type and ballast condition. Why Other Options Are Wrong: Nearby values (0.40, 0.44, 0.46, 0.50) do not reflect the standard reference value commonly assumed for design calculations. Common Pitfalls: Confusing gross plan area with effective bearing area. Final Answer: 0.42 m^2.

Question 4

Rule-of-thumb relationship: On Indian Railways, the ratio of axle load (tonnes) to rail weight (kg/m) commonly used for selection checks is approximately:

Accepted Answer

Introduction / Context: Preliminary rail selection often uses a quick check relating axle load (in tonnes) to rail section mass (in kg per metre). This rule-of-thumb does not replace full structural analysis but provides a fast screening for suitability. Given Data / Assumptions: Axle load expressed in tonnes. Rail section weight expressed in kg/m. Heuristic ratio used in Indian practice for initial checks. Concept / Approach: The empirical relation approximates the practical capacity of a rail section. A value near 5/12 (≈ 0.417) has long been referenced to ensure the rail mass is commensurate with expected axle loads, pending detailed verification (section modulus, speeds, sleeper density, maintenance standards). Step-by-Step Solution: 1) Express a screening ratio for quick selection.2) Adopt the commonly cited 5/12 value.3) Use it to verify that a chosen rail weight is reasonable for the planned axle loads. Verification / Alternative check: Compare with known practice: heavier rails (52–60 kg/m) support higher axle loads (≈ 20–25 t), which align with the 5/12 screening magnitude when converted consistently. Why Other Options Are Wrong: 3/12 or 4/12 are too low and may understate required rail mass. 6/00 is not a meaningful ratio in this context. None of these is incorrect because 5/12 is the recognized rule-of-thumb figure. Common Pitfalls: Treating the ratio as a code requirement; it is only an initial guide and must be followed by detailed design checks. Final Answer: 5/12.

Question 5

Crossover geometry: For two parallel tracks at center-to-center distance D, gauge G, and crossing angle α, what is the expression for the distance between the theoretical noses of the two crossings measured parallel to the tracks?

Accepted Answer

Introduction / Context: Designing a crossover between parallel tracks requires careful geometry of turnouts and crossings. The spacing between theoretical noses of the two crossings, measured parallel to the track centerline, depends on track spacing D, gauge G, and the crossing angle α. Given Data / Assumptions: D = center-to-center spacing of the two main tracks. G = track gauge. α = angle of crossing for the turnouts. Equal crossing angles and symmetric arrangement. Concept / Approach: The geometry resolves transverse separations into longitudinal distances using trigonometry. Because the nose-to-nose line is aligned parallel to the tracks, the relevant transverse components project by a factor of cot α. Adjustments for gauge are included due to the nose being at the gauge line, not track center. Step-by-Step Solution: 1) Represent the transverse offset between noses as the basic track spacing modified by gauge terms at a crossing.2) Determine the effective transverse separation: (D - G + G sec α).3) Project this separation along the parallel (track) direction using cot α to obtain the longitudinal nose spacing.4) Final expression: (D - G + G sec α) cot α. Verification / Alternative check: Check limiting cases: As α becomes small (flatter crossing), cot α grows and the nose spacing increases, which is physically consistent for flatter crossings requiring longer leads. Why Other Options Are Wrong: Signs in the gauge terms are incorrect in options (b) and (c), giving wrong effective separation. Using tan α in (c) projects in the wrong sense; the dimension should scale with cot α for small angles. (d) overestimates by adding both G and G sec α. Common Pitfalls: Ignoring that noses are located at gauge lines, not at track centers, leading to omission of gauge corrections. Final Answer: (D - G + G sec α) cot α.

Question 6

Track condition quantification: If a is the number of peaks > 10 mm of unevenness per km, b is peaks > 6 mm of gauge variation per km, and c is peaks > 2 mm twist per metre, what is the Composite Current Recording Index (Ic) recommended by Northern …

Accepted Answer

Introduction / Context: Track-recording cars measure defects in longitudinal level (unevenness), gauge variation, and twist. A composite index condenses these readings into a single value for maintenance prioritization. The Northern Railway formula is a commonly cited benchmark in Indian practice. Given Data / Assumptions: a = average peaks of unevenness > 10 mm per km. b = average peaks of gauge variation > 6 mm per km. c = average peaks of twist > 2 mm per metre. Concept / Approach: The composite index penalizes the Ic value for higher counts of defects. Unevenness and gauge peaks have full weight; twist is down-weighted (divided by 4) recognizing its different scaling/occurrence frequency. Step-by-Step Solution: Adopt the recommended form Ic = 30 - a - b - c/4.Interpretation: higher a, b, or c reduces Ic, signaling worse track condition.Plan maintenance when Ic drops below specified thresholds. Verification / Alternative check: Try sample values: if a = 10, b = 6, c = 8, then Ic = 30 - 10 - 6 - 2 = 12, indicating significant defects and need for attention. Why Other Options Are Wrong: 10, 20, or 40 as the constant base do not match the Northern Railway guidance for the stated thresholds. 50 is not standard for this formulation. Common Pitfalls: Mixing thresholds from different administrations or older manuals. Forgetting to divide twist peaks by 4. Final Answer: Ic = 30 - a - b - c/4.

Question 7

Ballast specification near pointwork: What is the maximum nominal ballast size permitted around points and crossings for reliable tamping and smooth wheel guidance?

Accepted Answer

Introduction / Context: Points and crossings require finer control of alignment and level. Large ballast particles can obstruct switch movement and prevent proper packing in confined spaces near stretcher bars and heel joints. Hence a smaller maximum size is specified. Given Data / Assumptions: Standard Indian practice near turnouts. Need for unobstructed switch operation and effective tamping. Concept / Approach: Reducing maximum ballast size improves interlock and packing in tight areas, enhancing stability and switch operation while minimizing the chance of ballast fouling moving parts. Step-by-Step Solution: Recognize special operational and geometric constraints at pointwork.Adopt finer grading with nominal maximum size 25 mm.Ensure cleanliness and adequate depth to maintain drainage and stiffness. Verification / Alternative check: Turnout maintenance guides specify smaller stone sizes around switch and crossing zones for smooth operation and reduced damage. Why Other Options Are Wrong: 50, 40, 30 mm: too large near moving parts and tight clearances. 20 mm: possible but not the standard upper limit; 25 mm is widely prescribed. Common Pitfalls: Using mainline ballast size (40–50 mm) in switch zones, causing obstruction and poor packing. Final Answer: 25 mm.

Question 8

Thermal behavior of rails: When rails move out of position due to insufficient expansion gaps on hot days, the phenomenon is called:

Accepted Answer

Introduction / Context: Rails expand with temperature. If expansion is restrained (inadequate gaps or high resistance), compressive forces build up and the track may buckle laterally, risking derailment. Recognizing this failure mode is essential for safe operations in hot climates. Given Data / Assumptions: Jointed or long-welded rail with insufficient allowance for thermal expansion. High rail temperatures causing compressive stresses. Concept / Approach: Thermal expansion without adequate relief creates axial compression. When the critical compressive load exceeds track lateral resistance, the rail alignment kinks—termed buckling or sun kink. Proper neutral temperature management and ballast resistance mitigate this risk. Step-by-Step Solution: Identify root cause: insufficient expansion gap or high locked-in temperature.Understand mechanism: compression leads to lateral instability (buckling).Name the phenomenon: buckling (sun kink). Verification / Alternative check: Inspection records often note lateral kinks during heat waves where expansion gaps were inadequate or anchors ineffective. Why Other Options Are Wrong: Creeping: slow longitudinal movement due to traffic forces, not sudden lateral instability. Hogging: vertical distortion usually at joints due to differential settlement/battering. None/Lipping: do not describe this thermal lateral deflection. Common Pitfalls: Confusing creep with thermal buckling; one is gradual longitudinal movement, the other is sudden lateral instability. Final Answer: Buckling (sun kink).

Question 9

Crossing components: Where are wing rails provided in a turnout/crossing assembly?

Accepted Answer

Introduction / Context: Wing rails are special rails that flank the nose of a crossing (the V) to guide wheel flanges safely across the gap at the crossing. Correct identification of their location is fundamental to turnout anatomy. Given Data / Assumptions: A standard turnout consists of switch (tongue and stock rails) and crossing (nose, wing rails, check rails). Concept / Approach: At the crossing, the wheel must bridge a gap. Wing rails provide the guiding surfaces and maintain the correct flangeway, working with check rails on the opposite rail to ensure smooth passage and prevent flange picking of the nose. Step-by-Step Solution: Identify the crossing portion (V-crossing).Wing rails are positioned adjacent to and diverging from the nose.Hence, the correct location is at the crossing. Verification / Alternative check: Standard turnout drawings show wing rails integral to the crossing assembly, clearly labeled and dimensioned. Why Other Options Are Wrong: Switch/tongue area: has tongue and stock rails, not wing rails. Check rails are separate components used opposite the crossing to control flange path, not in place of wing rails. Common Pitfalls: Mislabeling check rails as wing rails; both guide flanges but are in different positions and serve complementary roles. Final Answer: In crossing.

Question 10

Two-block concrete sleeper (twin-block) basics: Which of the following dimensions and weights correctly represent each individual block of a two-block concrete sleeper?

Accepted Answer

Introduction / Context: Two-block (twin-block) concrete sleepers consist of two reinforced concrete blocks connected by a steel tie bar. Their block dimensions and unit weights must be realistic for handling, installation, and design calculations. Overstated or understated values can signal incorrect data. Given Data / Assumptions: Each listing claims to represent each block of a twin-block sleeper. Typical handling weights for a single block are well below 200 kg to allow practical installation. Concept / Approach: Field experience and catalog values indicate each block generally weighs on the order of several tens of kilograms to around a hundred kilograms, not 200–280 kg. Combined sleeper assembly weights vary with gauge and design but remain manageable for mechanized handling. Step-by-Step Solution: Check plausibility: options (a), (b), (c) give per-block weights exceeding 200 kg, unrealistic for individual block handling.Examine dimensions: the sizes listed correspond to large monoblock footprints rather than single twin-block elements.Therefore, none of the options accurately represents a standard per-block specification. Verification / Alternative check: Manufacturer datasheets for twin-block sleepers show each block weight typically around 70–120 kg depending on design, far less than 215–280 kg claimed. Why Other Options Are Wrong: (a), (b), (c): grossly overestimate per-block weight and/or list unlikely dimensions. (e): appears more plausible in weight, but the dimensions are not standard; since the question asks for correct standard data, it is safer to reject all inconsistent entries. Common Pitfalls: Confusing overall sleeper assembly weight with the weight of each individual block. Final Answer: None of these.

Question 11

In railway track maintenance, “Burnettising” (also spelled Burnettizing) is a chemical preservation process. It is primarily applied to which track component to protect it against biological decay, termites, and moisture-related deterioration?

Accepted Answer

Introduction / Context: Timber used in railway tracks is susceptible to decay, fungal attack, and insect damage. To extend the service life of timber components, especially sleepers (ties), railways use preservative treatments. Burnettising is one such early method that injected preservative solutions into wood to resist bio-deterioration and moisture effects. Given Data / Assumptions: The term Burnettising refers to a timber preservation process using salts (historically zinc chloride solutions). Typical track elements: sleepers (wood), rails (steel), ballast (stone, cinders, sand, etc.). Objective is durability against rot and pests, not mechanical strengthening. Concept / Approach: Preservation methods for timber include creosoting, Burnettising, and other salt-based processes. These methods target wood's vulnerability to biological attack. Rails are steel and protected by metallurgical quality and sometimes corrosion-protection systems, while ballast is inert mineral aggregate and does not need such treatments. Step-by-Step Solution: Identify which component is timber: sleepers.Recall Burnettising is a wood-preservation technique.Conclude that the treated component is wooden sleepers. Verification / Alternative check: Standard permanent-way textbooks list Burnettising alongside creosoting under timber preservation, specifically for sleepers, poles, and other wood components in contact with soil and moisture. Why Other Options Are Wrong: Rails are steel; preservation entails corrosion control, not Burnettising. Ballast is mineral aggregate and does not undergo chemical preservation. “None of these” is incorrect because sleepers are indeed preserved. Common Pitfalls: Confusing wood preservation with metal corrosion protection; assuming all track materials use the same treatment. Final Answer: Wooden sleepers

Question 12

Sleeper density rule of thumb: If n is the standard rail length in metres, the typical number of sleepers provided per rail length on Indian Railways usually lies in which range?

Accepted Answer

Introduction / Context: Sleeper density (SD) expresses the number of sleepers per rail length, providing a quick guide to support and track stiffness. For a given rail length n (in metres), Indian Railway practice uses simple rules like n + x sleepers, where x depends on traffic, axle loads, and track category. Given Data / Assumptions: n denotes rail length in metres. We are considering typical mainline practice for Broad Gauge with conventional ballasted track. Answer sought is a customary range used in exams and handbooks. Concept / Approach: Higher sleeper density improves load distribution, gauge restraint, and track geometry retention. However, it increases material and maintenance costs. A compromise range widely cited is between n + 3 and n + 6 sleepers per 1 rail length, adapting to traffic and speed demands. Step-by-Step Solution: Recognize SD is expressed as n + x.Recall typical recommended range.Select the option that matches the common practice: (n + 3) to (n + 6). Verification / Alternative check: Permanent-way manuals provide ranges and specific sleeper densities for different track classes; the exam-standard range commonly quoted is (n + 3) to (n + 6). Why Other Options Are Wrong: n to (n + 2) is too sparse; (n + 2) to (n + 4) can be inadequate for heavier traffic; (n + 4) to (n + 5) is a narrower subset of the accepted range and not the typical full range cited. Common Pitfalls: Confusing sleeper density with sleeper spacing; forgetting that higher category tracks may adopt the higher end of the range. Final Answer: (n + 3) to (n + 6)

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