Horizontal Alignment of Highways - IES Previous Year Questions

11. Consider the following statements:

A transition curve is provided on a circular curve on a highway to provide. 

  1. Gradual introduction of centrifugal force.
  2. Minimum stopping sight distance.
  3. Gradual introduction of super elevation.
  4. Comfort and security to passengers.

Which of these statements are correct ?

[IES 2004]

  1. 2, 3 and 4
  2. 1, 3 and 4
  3. 1, 2 and 3
  4. 1, 2 and 4
Answer: Option B
Explanation:
The purpose of providing transition curves are as follows:
  • Gradual introduction of centrifugal force.
  • Gradual introduction of super elevation.
  • Provision of comfort and safety to the passengers.

12.  What will be the ruling radius of a horizontal curve on a National highway for a design vehicle speed of 100 kmph, assuming allowable super elevation to be 7% and lateral friction as 0.13 ?

[IES 2004]

  1. 395 m
  2. 375 m
  3. 405 m
  4. 385 m
Answer: Option A
Explanation:
Design speed, v = 100 kmph = 27.78 m/s
From the design of super elevation, e + f =
v2 / gR

⇒ 0.07 + 0.13 =
27.782 / 9.81 x R

⇒ R = 393.33 m
Thus, the ruling radius of the given horizontal curve = 393.33 m.
Here, the closest option is 395 m.

13.  Which of the following are requirements for the design of a transition curve for a highway system ?

  1. Rate of change of grade
  2. Rate of change of radial acceleration
  3. Rate of change of super elevation
  4. Rate of change of curvature

Select the correct answer using the codes given below:

[IES 2005]

  1. 2, 1 and 4
  2. 1, 3 and 4
  3. 2, 3 and 4
  4. 1, 2 and 3
Answer: Option C
Explanation:
The length of transition curve, L =
v3 / cR
(or) eNW (or)
2.7v2 / R
, whichever is maximum.
Hence, the design of the transition curve depends on
  • The rate of change of centrifugal acceleration (c),
  • The rate of change of super elevation (N) and
  • The radius of curvature (1/R)

14.  What is the minimum length of a transition curve for a design speed of 80 kmph in a horizontal curve of 240 m radius ?

[IES 2006]

  1. 72 m
  2. 32 m
  3. 42 m
  4. 52 m
Answer: Option A
Explanation:
Design speed, v = 80 kmph = 22.22 m/s
Rate of change of centrifugal acceleration, c =
80 / 75 + v

⇒ c =
80 / 75 + 80
= 0.52
  • Length of transition curve (Based on centrigugal acceleration),
L1 =
v3 / cR
=
22.22 3 / 0.52 x 240

⇒ L1 = 87.91 m
  • Also, the length of transition curve (Based on IRC standards, for plain and rolling terrain),
L2 =
2.7v2 / R
=
2.7 x 80 2 / 240

⇒ L2 = 72 m
Thus, minimum length of transition curve to be provided = Max (87.91, 72) = 87.91 m
But 87.91 m is not provided. Hence the correct option is 72 m.

15.  The design speed of a highway is 80 kmph and the radius of the circular curve is 150 m in plain topography. Which one of the following is the minimum length of transition curve ?

[IES 2006]

  1. 115 m
  2. 43 m
  3. 85 m
  4. 64 m
Answer: Option A
Explanation:
Design speed, v = 80 kmph = 22.22 m/s
Rate of change of centrifugal acceleration, c =
80 / 75 + v

⇒ c =
80 / 75 + 80
= 0.52
  • Length of transition curve (Based on centrigugal acceleration),
L1 =
v3 / cR
=
22.22 3 / 0.52 x 150

⇒ L1 = 140.65 m
  • Also, the length of transition curve (Based on IRC standards, for plain and rolling terrain),
L2 =
2.7v2 / R
=
2.7 x 80 2 / 150

⇒ L2 = 115.2 m
Thus, minimum length of transition curve to be provided = Max (140.65, 115.2) = 140.65 m
But 140.65 m is not provided. Hence the correct option is 115 m.

16.  If a road surface is adequately super elevated on a horizontal curve, which one of the following is the proper distribution of pressure on the vehicle wheels ?

[IES 2007]

  1. Pressure on the inner wheels is more than the outer wheels.
  2. Pressure on the inner wheels is less than the outer wheels.
  3. Pressure on both outer and inner wheels is equal.
  4. Pressure on the front wheel is thrice the pressure on rear wheels.
Answer: Option C
Explanation:
On a flat horizontal curve, the pressure on the outer wheels will be more than the pressure on the inner wheels of the vehicle. The provision of super elevation ensures equal pressure distribution on the outer and inner wheels of the vehicle.

17.  Assertion (A): Road camber helps in surface drainage.

Reason (R): In a curved road alignment, super elevation serves the purpose of camber.

[IES 2008]

  1. Both A and R are true and R is the correct explanation of A.
  2. Both A and R are true but R is not a correct explanation of A.
  3. A is true but R is false.
  4. A is false but R is true.
Answer: Option B
Explanation:
  • Camber provides surface drainage.
  • The super elevation is obtained by rotating the pavement with respect to the center or with respect to the inner edge. The super elevation serves as camber in a curved road alignment. Although super elevation provides surface drainage, its main purpose is to counteract the centrifugal force.

18.  If super elevation is not provided on a horizontal curve of a highway, then on which portion of the road, are pot holes likely to develop ?

[IES 2010]

  1. Outer edge of road
  2. Centre of road
  3. Inner edge of road
  4. Shoulder of road
Answer: Option A
Explanation:
In the absence of super elevation on a horizontal curve, the pressure on the outer wheels will be more than the pressure on the inner wheels. Hence, the potholes are developed on the outer edge of the road.

19.  Full amount of super elevation on a horizontal curve is provided at the _____ .

[IES 2010]

  1. Centre of the circular curve
  2. End of the transition curve
  3. Beginning of the transition curve
  4. Centre of the transition curve
Answer: Option B
Explanation:
A transition curve is provided when a horizontal curve meets a straight line and vice versa. The super elevation increases from zero at the beginning of a transition curve (i.e., at the end of straight line) and reaches the required value at the end of transition curve (i.e., at the beginning of horizontal curve)

20.  With all other relevant conditions remaining the same, the speed of a vehicle negotiating a curve is proportional to _____ .

[IES 2011]

  1. Weight of the vehicle
  2. 1 / Weight of the vehicle
  3. 1 / √ Weight of the vehicle
  4. √ Weight of the vehicle
Answer: Option C
Explanation:
Centrifugal ratio =
P / W
=
v2 / gR

⇒ V2 =
P x gR / W

⇒ V ∝
1 / √  W 
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