Highway Engineering PYQ – TN TRB Lecturer
21. Two cars are approaching each other from opposite directions at 100 km/h and 80 km/h respectively. The reaction time of each driver is 2.5 seconds and the coefficient of friction is 0.35. The stopping sight distance required in order to avoid head on collision of two cars will be _____ .
[TN TRB 2017: 1 Mark]
- 128 m
- 182 m
- 218 m
- 310 m
Explanation:
Design speed, v1 = 100 km/hr (or) 27.78 m/s and
V2 = 80 km/hr (or) 22.22 m/s
Stopping Sight Distance, SSD = SSD1 + SSD2
SSD1 = v1t +
2gf
⇒ SSD1 = (27.78 x 2.5) +
2 x 9.81 x 0.35
⇒ SSD1 = 181.83 m
Also, SSD2 = v2t +
2gf
⇒ SSD2 = (22.22 x 2.5) +
2 x 9.81 x 0.35
⇒ SSD2 = 127.45 m
Thus, SSD = 181.83 + 127.45 = 309.28 m
Here, the closest option is 310 m.
22. Which of the following bituminous binder is most suitable in cold – mix macadam and bituminous carpets at summer and winter temperatures, both in plains and in high altitudes?
[TN TRB 2017: 1 Mark]
- Emulsions
- Cutback RC – 3
- 60/70 Penetration grade
- 180/200 Penetration grade
Explanation:
At higher altitudes and in winter, the temperature will be lesser. Hence, in such conditions, the viscosity of bitumen is reduced not by heating but by adding volatile solvent. The bitumen in which the viscosity is reduced by adding volatile solvent is known as cutback bitumen.
23. In the trial cycle method, the green period G1 can be expressed as _____ .
[TN TRB 2017: 1 Mark]
- 2.5 n1 C1 900
- 3.5 n1 C1 600
- 900 n1 C1 2.5
- 600 n1 C1 2.5
Explanation:
As per trial cycle method, the green period is calculated using the formula
G1 =
900
24. Locality map cum site plan is a _____ .
[TN TRB 2017: 1 Mark]
- Combination of the key mapto a scale of 1 : 250,000 and the index map to a scale of 1 : 50,000
- Combination of the key mapto a scale of 1 : 50,000 and the index map to a scale of 1 : 20,000
- Combination of the key mapto a scale of 1 : 20,000 and the index map to a scale of 1 : 10,000
- Combination of the key mapto a scale of 1 : 150,000 and the index map to a scale of 1 : 25,000
Explanation:
Location map cum site plan is a combination of the keymap drawn to a scale of 1: 250,000 and the index map drawn to a scale of 1: 50,000. Location map cum site plan shows the location of the project in the and indicates the names of towns and cities.
25. The provided super elevation is said to be equilibrium superelevation, if _____ .
[TN TRB 2017: 1 Mark]
- Pressure on the inner wheel is more than that on the outer wheel
- Coefficient of friction is zero
- The rate of superelevation is very small
- The acceleration of the vehicle is negligible
Explanation:
The super elevation is said to be in equilibrium if the pressure on outer and inner wheels remain the same. In such a case, the coefficient of lateral friction is zero.
26. If V is the design speed in km/hr and ‘t’ is the total reaction time. The lag distance will be _____ .
[TN TRB 2017: 2 Marks]
- 0.378 V.t metres
- 0.178 V.t metres
- 0.278 V.t metres
- 0.478 V.t metres
Explanation:
The design speed in km/hr is converted to m/s by using a multiplication factor 0.278.
Hence, Lag distance (m) = 0.278 Vt
27. Match the items in List – A with items in List – B and choose the correct answer given below the lists:
List – A (Crack type)
- Alligator crack
- Shrinkage crack
- Sympathetic crack
- Hair line crack
List – B (Cause)
(i) Brittleness due to aging of binder
(ii) Brittleness and overheating of bitumen
(iii) Insufficient bitumen content
(iv) Joints and cracks on pavement layers underneath
[TN TRB 2017: 2 Marks]
Codes: (a) (b) (c) (d)
- (iv) (i) (ii) (iii)
- (ii) (i) (iv) (iii)
- (ii) (iv) (i) (iii)
- (ii) (iv) (iii) (i)
Explanation:
- Alligator crack occurs due to brittleness and overheating of bitumen.
- Shrinkage crack occurs due to brittleness which is a result of aging of binder.
- Sympathetic crack occurs due to the cracks formed on the underneath pavement layers.
- Hairline cracks occur due to insufficient bitumen content.
28. A traffic lane has one way traffic flow at a stream speed of 40 kmph. The average space gap between vehicles to follow 0.278 Vt. Assuming the average reaction time as 0.7 sec and average length of vehicle as 5m, the theoretical capacity calculated with above data in vehicles per hour per lane will be _____ .
[TN TRB 2017: 2 Marks]
- 2170
- 2350
- 2840
- 3130
Explanation:
Since, reaction time is lesser than 2 secs,
Space Headway, S = 0.278 Vt + L
⇒ S = (0.278 x 40 x 0.7) + 5 = 12.78 m
Theoretical capacity, C =
S
x V =
12.78
x 40
⇒ C = 3129. 89 ≈ 3130 veh per hour
29. In an old map, a line AB was drawn to a magnetic bearing of 8°30’. The magnetic declination at that being 2° East. To what magnetic bearing should the line be set so that the present magnetic declination is 8°30’ East.
[TN TRB 2017: 2 Marks]
- 2° (Anticlockwise direction)
- 2° (Clockwise direction)
- 358° (Clockwise direction)
- 0°
Explanation:
Eastward declination is positive and Westward declination is negative.
When magnetic declination is 2° East,
True bearing = Magnetic Bearing + Declination = 8°30’ + 2° = 10°30’
When magnetic declination is 8°30’ East,
True bearing = Magnetic Bearing + Declination
⇒ 10°30’ = MB + 8°30’
⇒ MB = 2°
Magnetic Bearing is the bearing measured clockwise from magnetic north.
Hence, the correct option is 2° (Clockwise direction)
30. Two parallel lines are to be connected. What type of curve would you suggest ?
[TN TRB 2017: 1 Mark]
- Reverse curve
- Compound curve
- Lemiscate curve
- Simple curve
Explanation:
Reverse curve is more suitable for connecting two parallel lines.