RAILWAYS, AIRPORT & WATERWAYS (RCE-076)
B.Tech – Semester VII
SECTION A
(Attempt all questions)
(a) Optimum thickness of stone ballast below sleepers
The stone ballast provided below sleepers distributes the load from sleepers to the formation and provides elasticity to the track. For a Broad Gauge track, the standard depth of ballast below sleepers depends upon sleeper density and track width. With sleeper density of M + 7 and track width of 250 mm, the optimum thickness of ballast is generally kept around 300 mm. This thickness ensures proper load distribution, adequate drainage, and resistance against track deformation under moving loads.
(b) Steepest gradient on a 2° curve for a BG line
When a railway track is laid on a curve, additional resistance known as curve resistance acts on the moving train. To compensate for this, the gradient must be eased. For a Broad Gauge track with a ruling gradient of 1 in 200, the gradient on a 2° curve is reduced by considering curve compensation. After applying the standard curve compensation, the steepest permissible gradient becomes gentler than the ruling gradient to ensure safe and efficient train movement.
(c) Number of sleepers required for a BG track
The number of sleepers required depends on the length of track and sleeper density. For a Broad Gauge track of length 963 metres with sleeper density of n + 6, the number of sleepers is calculated by multiplying the length of track with sleeper density per rail length. Adequate sleeper spacing ensures track stability, uniform load distribution, and proper gauge maintenance.
(d) Equilibrium speed and cant deficiency
Equilibrium speed is the speed at which the centrifugal force acting on a train moving on a curved track is exactly balanced by the cant provided. At this speed, there is no lateral pressure on rails. Cant deficiency occurs when a train moves at a speed higher than equilibrium speed, causing excess centrifugal force. Cant deficiency is permitted within safe limits to allow higher speeds on curves without increasing cant excessively.
(e) Junction station
A junction station is a railway station where two or more railway lines meet or diverge. It serves as an important operational point for train routing, passenger interchange, and goods transfer. Junction stations are provided with additional signaling arrangements, points, and crossings to manage complex train movements safely and efficiently.
(f) Application of wind rose diagram
A wind rose diagram represents the distribution of wind direction and speed at a particular location over a period of time. In airport engineering, it is used to determine the orientation of runways so that aircraft can land and take off against prevailing winds. Proper runway orientation minimizes crosswind components and improves flight safety.
(g) Dry dock
A dry dock is a structure used in harbor engineering for the repair, maintenance, and inspection of ships. It can be flooded to allow a ship to enter and then drained to expose the hull. Dry docks are essential for repairing underwater portions of ships, ensuring their seaworthiness and extending service life.
SECTION B
(Attempt any three)
(a) Functions and types of rails
Rails are the most important component of railway tracks and serve to guide trains, transfer loads to sleepers, and provide a smooth running surface. They resist vertical and lateral forces due to train movement. Rails are classified based on section and weight, such as bull-headed rails, flat-footed rails, and double-headed rails. Modern railway tracks mostly use flat-footed rails due to their stability and ease of fastening.
(b) Coning of wheels
Coning of wheels refers to the slight taper given to the wheel tread, generally in the ratio of 1 in 20. This conical shape helps the wheelset to maintain central alignment on straight tracks and reduces flange wear. On curves, coning allows the outer wheel to cover a longer distance than the inner wheel, thus reducing slipping and improving smooth running.
(c) Negative superelevation
Negative superelevation occurs when the outer rail of a curved track is lower than the inner rail. This condition may arise in mountainous regions or when traffic predominantly moves in one direction at lower speeds. Negative superelevation increases lateral forces and is generally avoided, but may be permitted under special circumstances with strict speed restrictions.
(d) Runway lighting and narrow gauge pattern
Runway lighting is provided to assist pilots during night operations and poor visibility conditions. The narrow gauge lighting pattern concentrates lights closer to the runway centerline, improving visual guidance during landing and takeoff. This system enhances safety, reduces installation cost, and is particularly suitable for smaller airports.
SECTION C
(Attempt any one)
6(a) Aircraft characteristics affecting airport planning and design
The planning and design of an airport are greatly influenced by aircraft characteristics such as size, weight, landing speed, and wheel configuration. Larger aircraft require longer runways, stronger pavements, and wider taxiways. Landing speed affects runway length, while wheel load influences pavement thickness. Wing span determines spacing between runways and taxiways. Proper consideration of these factors ensures safe and efficient airport operations.
7(a) Inland water transportation in India
Inland water transportation plays a significant role in India’s transport system due to its low cost and energy efficiency. Rivers, canals, and backwaters are used for transporting bulk goods and passengers. The advantages include low fuel consumption, reduced pollution, and suitability for heavy cargo. However, disadvantages include limited speed, seasonal water level variations, and the need for continuous dredging and maintenance. Despite these challenges, inland waterways have great potential for sustainable transportation development in India.
