Q1
(a) (i) What is the purpose of first coat of plastering ? (ii) What loads are taken by the formwork apart from its self-weight ? (iii) Label the components (1, 2, 3 & 4) of pitched roof shown in the figure. 10 marks (b) Convert the given A-O-A (Activity on Arrow) to A-O-N (Activity on Node) Network and indicate the critical path. The duration of each activity is shown in the figure. 10 marks (c) The staff reading taken on a staff held at a distance of 80 m from the instrument when the bubble central was 1·455 m. When the bubble is moved 6 divisions out of centre, the staff reading observed is 1·487 m. If the length of one division is 2 mm, find the radius of curvature and the sensitivity of the tube. 10 marks (d) What is vertical curve and its significance ? Draw summit as well as valley curve for the following conditions : (i) Upward gradient (+g₁%) followed by another upward gradient (+g₂%) (ii) Downward gradient (−g₁%) followed by another downward gradient (−g₂%) 10 marks (e) A locomotive on M. G. Track has three pairs of driving wheels each carrying 20 tonnes. What maximum load can it pull on level track with curvature of 2° at 50 km/hr ? Take coefficient of friction = 0·166. 10 marks
हिंदी में प्रश्न पढ़ें
(a) (i) प्लास्टर के पहले लेप का उद्देश्य क्या है ? (ii) फर्मवर्क (फॉर्म वर्क) द्वारा अपने स्वयं के भार के अलावा और कौन से भार वहन किए जाते हैं ? (iii) ढालू छत के, दिए गए चित्र में दर्शाए गए अंगों (1, 2, 3, 4) को नामांकित कीजिए । 10 अंक (b) दिए गए ए-ओ-ए (शर पर क्रिया) जाल को ए-ओ-एन (संधि पर क्रिया) जाल में परिवर्तित कीजिए एवं क्रांतिक पथ इंगित कीजिए । प्रत्येक क्रिया की समयावधि चित्र में दर्शाई गई है । 10 अंक (c) उपकरण से 80 m की दूरी पर स्थित गज (स्टाफ) पर गज पाठ्यांक, बुलबुले के केंद्र में होने पर 1·455 m था । जब बुलबुले को केंद्र से 6 भाग बाहर खिसकाया गया, तब गज पाठ्यांक 1·487 m में देखा गया । यदि एक भाग की लंबाई 2 mm है, तो समतलन नलिका की वक्रता की त्रिज्या एवं सुग्राहिता ज्ञात कीजिए । 10 अंक (d) उद्वर्धर वक्र क्या है एवं इसका महत्व क्या है ? निम्नलिखित स्थितियों के लिए शिखर (समिट) वक्र और घाटी वक्र का चित्र बनाइए : (i) उद्वमुखी ढाल (+g₁%) के बाद एक और उद्वमुखी ढाल (+g₂%) (ii) अधोमुखी ढाल (−g₁%) के बाद एक और अधोमुखी ढाल (−g₂%) 10 अंक (e) एम. जी. रेलपथ पर एक रेल इंजिन के तीन जोड़ी चालक पहिये हैं जो प्रत्येक 20 टन वहन कर रहे हैं । एक समतल रेलपथ पर, 2° वक्रता के साथ एवं 50 km/hr पर यह कितना अधिकतम भार खींच पाएगा ? घर्षण गुणांक 0·166 लीजिए । 10 अंक
Directive word: Solve
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How this answer will be evaluated
Approach
This multi-part question requires solving five distinct technical problems across building construction, project management, surveying, highway engineering, and railway engineering. Allocate approximately 2 minutes per mark (20 minutes per part), presenting each sub-part (a) through (e) as separate, clearly labelled sections. Begin with direct answers for theoretical parts, show complete numerical working for calculation-based parts, and ensure diagrams are neatly drawn with proper labelling.
Key points expected
- Part (a): Purpose of first coat plastering (keying surface, leveling, damp-proofing); formwork loads (fresh concrete weight, construction live loads, wind, vibration, impact); correct identification of pitched roof components (rafter, purlin, tie beam, king post/queen post)
- Part (b): Correct conversion from A-O-A to A-O-N network topology; accurate forward and backward pass calculations; identification of critical path with zero float activities
- Part (c): Application of sensitivity formula n = (S/R) × 206265 seconds; correct calculation of angle change from bubble displacement; derivation of radius of curvature R = S × D / α in arc-seconds
- Part (d): Definition of vertical curve as transition curve in elevation; significance for sight distance, comfort, drainage; correct geometric sketches for both summit curves (convex) and valley curves (concave) with tangent lengths
- Part (e): Application of Indian Railways tractive effort formula considering curve resistance (0.01° per degree), friction limitation, and speed-dependent factors; correct unit conversions for metre gauge conditions
Evaluation rubric
| Dimension | Weight | Max marks | Excellent | Average | Poor |
|---|---|---|---|---|---|
| Concept correctness | 20% | 10 | Precise technical definitions across all parts: plastering purposes include keying and suction control; formwork loads cover hydrostatic pressure and dynamic effects; vertical curve significance explicitly links to IRC sight distance standards; railway curve resistance correctly applies Indian Railways practice | Generally correct concepts with minor inaccuracies: vague plastering purposes, incomplete formwork load list, basic vertical curve definition without IRC context, curve resistance formula partially correct | Fundamental conceptual errors: confusing first coat with finishing coat, omitting concrete pressure in formwork, incorrect curve types for given gradients, applying broad gauge formulas to metre gauge |
| Numerical accuracy | 20% | 10 | All calculations error-free with proper significant figures: sensitivity = 20 arc-seconds, R ≈ 103.3 m for part (c); critical path duration correctly computed; tractive effort calculation includes proper curve resistance (2° → 2 kg/tonne) and speed check against adhesion limit | Correct method with arithmetic slips: one calculation error in sensitivity or radius; minor errors in network float calculations; curve resistance applied but final answer slightly off | Major numerical errors: wrong formula application, unit conversion failures (km/hr to m/s), incorrect sensitivity calculation using degrees instead of arc-seconds, ignoring curve resistance entirely in railway problem |
| Diagram quality | 20% | 10 | Clear, labelled diagrams: pitched roof shows structural hierarchy (rafter→purlin→truss); A-O-N network uses correct node-activity convention with clear arrows; vertical curves show tangent points, PVC/PVT, gradient angles; neat freehand acceptable but geometrically accurate | Recognizable diagrams with minor flaws: some roof component mislabelling, A-O-A accidentally drawn instead of A-O-N, vertical curves lacking tangent point markings, disproportionate sketches | Poor or absent diagrams: unrecognizable roof structure, network diagram omitted, vertical curves drawn without understanding convex/concave distinction, no labels or wrong labels throughout |
| Step-by-step derivation | 20% | 10 | Logical progression visible in all derivations: sensitivity derivation shows α = nS/R relationship; network conversion explicitly maps activities to nodes; vertical curve length formulas (L = NS²/4.4 for summit, L = NS²/3.2 for valley per IRC); railway problem shows adhesion check before final answer | Some steps shown but gaps remain: final formula stated without derivation, network converted without showing mapping, vertical curve lengths stated without formula reference, railway calculation jumps to answer | No derivations or logical flow: answers appear without working, formulas used without stating, no intermediate values shown, impossible to trace error sources |
| Practical interpretation | 20% | 10 | Contextual application to Indian practice: plastering mentions IS 1661 and 20mm thickness for first coat; formwork references IS 14687; vertical curves cite IRC:38 for design speeds; railway problem notes metre gauge limitations and compares with BG standards; sensitivity result assessed as acceptable for ordinary levelling | Limited practical context: generic statements about quality, brief mention of codes without specifics, no gauge-specific considerations, sensitivity stated without assessing instrument suitability | No practical awareness: purely theoretical treatment, no code references, ignores Indian conditions (dust affecting plaster adhesion, monsoon drainage for valley curves), no interpretation of whether answers are reasonable |
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