THEORY EXAMINATION (SEM–VI) 2016-17 TRANSPORTATION ENGINEERING-II

TRANSPORTATION ENGINEERING – II (ECE603)

Section-wise Solved Answers & Notes

SECTION – A (10 × 2 = 20 Marks)

Very short, precise answers

(a) Sub-grade

Sub-grade is the natural soil prepared and compacted to support the pavement structure. It acts as the foundation of the track/road.

(b) Steel vs Cast Iron

(c) A.N.C. and T.N.C.

• ANC (Absolute Negative Cant): Cant provided opposite to required cant.
• TNC (Total Negative Cant): Sum of provided cant and cant deficiency in opposite direction.

(d) Bearing plate

Bearing plate is a steel plate placed between rail and sleeper to distribute load uniformly and reduce wear on sleepers.

(e) Track drainage

Track drainage is the removal of surface and sub-surface water from railway tracks to maintain stability and prevent track failure.

(f) Marshalling yard

A marshalling yard is used for sorting and rearranging wagons to form new trains based on destination.

(g) Absolute block system

A system where only one train is allowed in a block section at a time, ensuring maximum safety.

(h) Interlocking

Interlocking is an arrangement that prevents conflicting movements of trains by mechanically or electrically linking signals and points.

(i) Track resistance

Track resistance is the force opposing the motion of a train, including rolling resistance, air resistance, gradient resistance, and curve resistance.

(j) Cant deficiency

Cant deficiency is the difference between equilibrium cant and actual cant provided when a train runs faster than equilibrium speed.

SECTION – B (Attempt Any FIVE) (5 × 10 = 50 Marks)

(a) Issues in rail fastenings

Rail fastenings secure rails to sleepers.

Issues include:                                      • Loosening due to vibration
• Corrosion                                             • Fatigue failure
• Maintenance difficulty                         • Thermal expansion effects

Proper fastenings improve safety, durability, and riding comfort.

(b) Concrete and pre-stressed concrete sleepers

Concrete sleepers:                               • Long life
• High stability                                       • Suitable for high-speed tracks

Pre-stressed concrete sleepers:
• Higher strength                                   • Crack resistance
• Better load distribution

Used widely in modern railway tracks.

(c) Super-elevation & negative super-elevation

Super-elevation: Raising outer rail on a curve to counter centrifugal force.

e=Gv2127Re = \frac{G v^2}{127 R}e=127RGv2​

Negative super-elevation: When inner rail is raised (rare, used in special conditions).

Example:
For high-speed rail curves to reduce derailment risk.

(d) Types of railway yards

• Passenger yard – passenger trains        • Goods yard – loading/unloading
• Marshalling yard – sorting wagons       • Locomotive yard – engine maintenance

Example: Tughlakabad Marshalling Yard, Delhi.

(e) Aircraft characteristics affecting airport design

• Aircraft speed                                          • Wing span
• Wheel load                                               • Turning radius
• Landing & take-off distance

Example: Larger aircraft require longer runways and wider taxiways.

(f) Mechanical interlocking for two-line station

Mechanical interlocking uses levers, rods, and bars to ensure correct sequence of signal and point operation.

Example:
Signal cannot be cleared unless points are correctly set.

(g) Points and crossings

Used to divert trains from one track to another.

Components:
• Switch rails                                                  • Stock rails
• Frog (crossing)

Example: Turnouts at junction stations.

(h) Ballast

Ballast is broken stone placed under sleepers.

Functions:
• Load distribution                                       • Drainage
• Track stability

Specifications:                                           • Size: 20–65 mm
• Hard, angular, durable

Screening: Removal of fines to restore drainage.

SECTION – C (Attempt Any TWO) (2 × 15 = 30 Marks)

Q3. Runway Length Correction (Numerical)

Given:
• Landing length (sea level) = 3000 m           • Take-off length (sea level) = 2500 m
• Elevation = 150 m                                       • Aerodrome reference temp = 25°C
• Standard temp at elevation = 14.025°C      • Effective gradient = 0.5%

(i) Elevation correction

Increase 7% per 300 m:  =150/300×7=3.5%= 150/300 \times 7 = 3.5\%=150/300×7=3.5%

(ii) Temperature correction

ΔT=25−14.025=10.975∘C\Delta T = 25 - 14.025 = 10.975^\circ CΔT=25−14.025=10.975∘C

Increase 1% per °C:

=10.975%= 10.975\%=10.975%

(iii) Gradient correction                      Increase 20% per 1% gradient:

=0.5×20=10%= 0.5 \times 20 = 10\%=0.5×20=10%

(iv) Corrected runway length (take-off governs)

L=2500×(1+0.035+0.10975+0.10)L = 2500 \times (1+0.035+0.10975+0.10)L=2500×(1+0.035+0.10975+0.10) L≈3110 m (approx.)L \approx \boxed{3110 \text{ m (approx.)}}L≈3110 m (approx.)​ 

Q4. Harbour – Design Factors

Harbour: A sheltered water area for ships to anchor safely.

Design factors:

• Location & depth                       • Wave action & tides
• Soil condition                             • Wind direction
• Cargo type                                 • Future expansion

Example: Mumbai Harbour.

Q5. Classification & Types of Signals

Criteria for classification               • Function
• Location                                     • Method of operation
• Colour/light

Types of signals

• Semaphore signals                    • Colour light signals
• Distant signals                           • Home signals

Semaphore signal (working)

Uses mechanical arms:
• Horizontal – Stop                       • Inclined – Caution
• Vertical – Clear

(Neat block diagram to be drawn in exam)