# Horizontal Alignment of Highways - IES Previous Year Questions

21.â€ƒAn ideal horizontal transition curve is a _____ .

**[IES 2012]**

- Parabola
- hyperbola
- Clothoid spiral
- Circle

**Answer:**Option C

**Explanation:**

IRC suggests the use of spiral as the horizontal transition curve for highways because,

- The spiral curve satisfies the requirements of an ideal transition.
- The setting out of the spiral curve is simpler and easier when compared with other transition curves.

22. â€ƒThe transition property of a lemniscate curve is disrupted when its deflection angle is around _____ .

**[IES 2012]**

- 45Â°
- 60Â°
- 90Â°
- 30Â°

**Answer:**

**Explanation:**

23. â€ƒIf R is the radius of the curve and L is the length of the long chord, the shift of the curve is _____ (all in meter units).

**[IES 2012]**

- L
^{2}/ R - L
^{2}/ 2R - L
^{2}/ 24R - L
^{2}/ 6R

**Answer:**Option C

**Explanation:**

The shift of the curve, S =

^{2}/ 24R

Where,

L - Length of the long chord.

R - Radius of the curve.

24. â€ƒFor a bituminous carriageway surface having 2% camber and design speed of 100 kmph, radius beyond which super elevation is not essential is nearly _____ .

**[IES 2013]**

- 1500 m
- 1800 m
- 2200 m
- 1100 m

**Answer:**Option C

**Explanation:**

Design speed, v = 100 kmph = 27.78 m/s

The camber provided will act as super elevation.

Super elevation, e =

^{2}/ gR

⇒ 0.02 =

^{2}/ 9.81 x R

⇒ R = 2212.5 m

Here, the closest option is 2200 m.

25. â€ƒThe rate of super elevation for a horizontal curve of radius 500 m in a national highway for a design speed of 100 kmph is _____ .

**[IES 2013]**

- 0.063
- 0.07
- 0.70
- 0.04

**Answer:**Option C

**Explanation:**

Design speed, v = 100 kmph = 27.78 m/s

Super elevation, e =

^{2}/ gR

⇒ e =

^{2}/ 9.81 x 500

But, maximum super elevation for plain terrain, e

_{max}= 0.07

Since e > e

_{max}, e = 0.07.

Now, e + f =

^{2}/ gR

⇒ 0.07 + f =

^{2}/ 9.81 x 500

⇒ f = 0.087 < 0.15

Hence, super elevation to be provided = 0.07

26. â€ƒThe maximum super elevation to be provided on a road curve is 1 in 15. If the rate of change of super elevation is specified as 1 in 120 and the road width is 10 m, then the minimum length of the transition curve on each end will be _____ .

**[IES 2015]**

- 100 m
- 80 m
- 180 m
- 120 m

**Answer:**Option B

**Explanation:**

Super elevation, e = 1/15

Rate of change of super elevation, N = 120

Width of the road, W = 10 m

Thus, minimum length of transition length assuming that the pavement is rotated with respect to inner edge,

L = eNW =

⇒ L = 80 m

27. â€ƒThe radius of a horizontal circular curve is 480 m and design speed therein 70 kmph. What will be the equilibrium super elevation for the pressures on the inner and outer wheels to be equal ?

**[IES 2015]**

- 6%
- 7%
- 8%
- 5%

**Answer:**Option C

**Explanation:**

Design speed, v = 70 kmph = 19.44 m/s

Equilibrium super elevation, e

_{equil}=

^{2}/ gR

^{2}/ 9.81 x 480

⇒ e

_{equil}= 0.08 (or) 8%

28. â€ƒThe following purposes served by a transition curve in a highway alignment include:

- Gradual introduction of the centrifugal force on moving vehicles from zero on the straight alignment to a constant final value on the circular curve.Â
- Enabling the gradual introduction of super elevation on the roadway.Â

Select the correct answer using the codes given below:

**[IES 2017]**

- 2 only
- Both 1 and 2
- Neither 1 nor 2
- 1 only

**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.

29. â€ƒThe rate of equilibrium super elevation on a road is _____ .

- Directly proportional to the square of vehicle velocity.
- Inversely proportional to the radius of the horizontal curve.
- Directly proportional to the square of the radius of the horizontal curve.

Which of the above statements are correct ?

**[IES 2018]**

- 1 and 3 only
- 2 and 3 only
- 1, 2 and 3
- 1 and 2 only

**Answer:**Option D

**Explanation:**

The equilibrium super elevation, e

_{equil}=

^{2}/ gR

Where,

v - Design speed of vehicle.

g - Acceleration due to gravity.

R - Radius of the horizontal curve.

30. â€ƒWhat is the extra widening required (as nearest magnitude) for a pavement of 7 m width on a horizontal curve of radius 200 m, if the longest wheel of vehicle expected on the road is 6.5 m and the design speed is 65 kmph ?

**[IES 2019]**

- 0.5 m
- 0.7 m
- 0.9 m
- 0.3 m

**Answer:**Option B

**Explanation:**

Mechanical widening, W

_{em}=

^{2}/ 2R

^{2}/ 2 x 200

⇒ W

_{em}= 0.21 m

Pyschological widening, W

_{ep}=

⇒ W

_{ep}= 0.48 m

Thus, total extra widening required, We = W

_{em}+ W

_{ep}= 0.21 + 0.48

⇒ W

_{e}= 0.69 m ≈ 0.70 m