(a) (i) Explain with neat sketches, how surface and sub-surface water can be removed from a railway track.

(ii) Two high level platforms are to be provided on the inside as well as the outside of a 2° curve on a BG track with a super-elevation of 10

Question

(a) (i) Explain with neat sketches, how surface and sub-surface water can be removed from a railway track.

(ii) Two high level platforms are to be provided on the inside as well as the outside of a 2° curve on a BG track with a super-elevation of 100 mm. What should be the required extra clearances for these platforms, both on the inside and the outside of the curve (length of bogie = 21·34 m, C/C bogie distance = 14·785 m, height of platform = 840 mm). 10+10

(b) The altitude of two proposed stations A and B 130 km apart are respectively 225 m and 1160 m. The altitude of two peaks C and D on the profile between them are respectively 308 m and 632 m, the distance being AC = 50 km and AD = 90 km. Determine whether A and B are intervisible, and if necessary find the minimum height of a scaffolding at B, assuming A as the ground station, to make them intervisible. 15

(c) How do you define an infrastructure project ? How do you compare BOO and BOOT models ? Draw a typical structure of a BOOT project. 15

UPSC Answer Check · Accepted Answer

Begin with a brief introduction acknowledging the multi-disciplinary nature of the question spanning railway engineering, geodetic surveying, and infrastructure financing. Allocate approximately 40% effort to part (a) combining drainage sketches with curve clearance calculations, 30% to part (b) for the intervisibility problem with proper profile diagram, and 30% to part (c) for conceptual comparison of PPP models with a neat BOOT structure diagram. Conclude with a synthesis on integrated infrastructure planning.
- Part (a)(i): Surface water removal via side drains, catch water drains, and proper ballast section; sub-surface water removal via cross drains (drainage layer), pipe drains, and inverted filters with neat sectional sketches
- Part (a)(ii): Calculation of extra clearances on curves using IRC formulae: overthrow (C1), end-throw (C2), lean due to superelevation (C3), and shift; application to inside and outside platforms with 840mm height consideration
- Part (b): Application of line of sight formula considering earth's curvature and refraction (k=0.07); calculation of minimum height of sight line above peaks C and D; determination of non-intervisibility and scaffolding height at B using Indian Survey standards
- Part (c): Definition of infrastructure project with characteristics (public good nature, high capital cost, long gestation, externalities); systematic comparison of BOO vs BOOT on ownership, transfer, financing risk, and government role; typical BOOT structure diagram showing SPV, concessionaire, lenders, and government relationships
- Part (c) continued: Indian examples such as Delhi Metro (PPP variants), NHAI BOT projects, or airport privatization to illustrate BOOT application

Dimension	Weight	Max marks	Excellent	Average	Poor
Concept correctness	20%	10	Demonstrates precise understanding of: (a) IRC provisions for track drainage and curve clearances including lean due to superelevation, (b) geodetic survey principles with correct application of curvature and refraction corrections, (c) infrastructure economics distinguishing BOO/BOOT with risk allocation matrices; cites relevant IRC codes or Indian PPP experience	Covers basic concepts but with minor errors: vague on drainage layer specifications, omits lean calculation in curve clearances, uses simplified line-of-sight without refraction, or presents generic PPP definitions without Indian context	Fundamental misconceptions: confuses surface/sub-surface drainage methods, applies wrong curve clearance formulae, ignores earth's curvature in intervisibility, or cannot distinguish BOO from BOOT ownership structures
Numerical accuracy	20%	10	All calculations precise: (a)(ii) correct overthrow (C1=44.5mm), end-throw (C2=64.2mm), lean (C3=52.5mm), and total extra clearances for inside/outside platforms; (b) accurate line-of-sight elevation calculations showing non-intervisibility with correct scaffolding height at B (typically 15-20m range)	Correct method but arithmetic slips: wrong decimal placement in curve parameters, approximate lean calculation, or minor errors in distance proportioning for peak elevations; final answers in reasonable range	Serious calculation errors: wrong formula application (e.g., degree curve radius), ignores units conversion, completely wrong intervisibility conclusion, or omits numerical working entirely
Diagram quality	20%	10	Three excellent diagrams: (a)(i) labeled cross-section showing surface drains (catch water, side drain) and sub-surface drainage (blanket layer, pipe drains); (a)(ii) plan and elevation of curved track with platform clearances marked; (c) clear BOOT structure showing SPV, concession agreement, off-take contracts, and financing flow with Indian project example	Diagrams present but incomplete: missing labels on drainage layers, no dimensioning on curve clearance sketch, or generic PPP diagram without BOOT-specific transfer element; legible but not examination-standard	Diagrams absent or unintelligible: rough sketches without labels, confused drainage sections, or completely wrong BOOT structure showing government ownership throughout; poor use of space
Step-by-step derivation	20%	10	Systematic derivation: (a)(ii) explicit statement of IRC formulae for C1, C2, C3 with substitution of given values (R=1720m for 2° curve); (b) clear elevation profile with station heights, sight line equation, and verification against peaks C and D; logical progression with units maintained throughout	Some steps shown but gaps exist: jumps from formula to answer without intermediate values, omits radius calculation from degree of curve, or presents final answers without showing peak clearance checks	No derivations shown: bald answers without formulae, random calculations without logical flow, or complete omission of numerical working for parts (a)(ii) and (b)
Practical interpretation	20%	10	Connects theory to practice: discusses Indian Railway maintenance practices for waterlogging-prone zones (e.g., Konkan Railway), explains why high-level platforms need extra clearance for passenger safety, relates intervisibility to actual survey tower heights in Himalayan terrain, and evaluates BOOT suitability for Indian highways/urban rail citing Delhi-Meerut RRTS or Mumbai Metro Line 3	Limited practical context: generic statements about drainage importance, standard safety mentions for platforms, or basic PPP advantages without specific Indian project evaluation	No practical application: purely theoretical treatment, fails to mention Indian Railway standards (IRC:24, IRC:38), ignores real-world survey constraints, or presents BOOT as universal solution without sector-specific analysis

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