Important Question And Answer: Civil - Geometric Design Of Highways

1. Define sight distance?

Sight distance in the actual length of road over which a driver sitting at a specified height in a vehicle can see objects either moving (or) stationary on the road surface.

2. What are classifications of sight distance depending upon the situation?

1. Stopping sight distance

2. Sate overtaking sight distance

3. Sight distance at intersection

3. Define S.S.D?

Stopping sight distance is the minimum distance required with in which a vehicle moving at designed speed can be stopped without colliding with a stationary object on the road surface.

4. What is the height of driver eye above the road surface?

IRC recommended height of driver eye is 1.22m.

5. Define reaction time:-

It is the time in seconds which a driver can take from the instant the objects visible to him to the instant the brakes are effectively applied.

6. Define perception period?

Perception period is the time taken by an average driver to realize a danger a head before actually trying to apply the breaker.

7. Define overtaking sight distance (OSD)

The distance visible to the driver of a vehicle intending to overtake another slow moving vehicle, without causing any inconvenience (or) possibility of accident to the traffic in the opposite direction in called overtaking sight distance (or) safe passing sight distance.

8. Define design speed?

Design speed can be defined as the speed which is permissible for safe and comfortable driving on a given surface of the highway.

9. What are the two effects of centrifugal force?

1. Tendency to overturn the vehicle.

2. Tendency to skid the vehicle laterally.

10.        Define super elevation?

The outer edge of the road in raised above the inner edge called super elevation (or) cant (or) banking.

11. What is the relation between super elevation, continuant of friction and centrifugal force

e+f=v²/9.8R e = super elevation whose value is taken an 40 (or) 1/15 f = Lateral frictional coefficient whose value in R = Radian of curve in

metros. g = 9.8

V = speed of vehicle in m/sec.

13. Define horizontal curve?

It is a curve in plan to provide change in the direction of the central time by the road surface.

14.           What are the factors attesting the design of curve?

1.Design speed of the vehicle

2.Allowable friction

3.Maximum allowable super elevation.

4.Permissible centrifugal ration.

15.           Define vertical curve?

It is a curve in the longitudinal section of a highway to provide a easy change of the gradient.

16.           What are curve used in a highway.

1.Circular curve

2.Transition curve

3.Parabolic curve

17.           What is the value of radian of the simple curve?

R= 1720m app

18.           Define compound curve?

A compound curve currish of a serial of hoot (or) more simple curve that run in the same direction and joint at common tangent point.

19. Define Reverse curve?

A reverse curve consist of two simple curve opposite direction that point at the common tangent point. This common point in called the point of reverse curve

20.           What are the types of transition curve?

1.True spiral (or clothed.

2.cubic spiral.

3.cubic parabolic.

4. Lemniscate's.

21.           What are characteristics of Transition curve?

1. It should meet the straight path tangentially

2. It should meet the circular curve tangentially

22.           What is the equation of a spiral transition curve?

Ls = m Ö  Q

Where m = Ö2 RL = a constant

Q = tangent of deflection angle in radians

23.           How many methods to determine the length of transition curve?

(1) By the rate of charge of radial acceleration

(2) By empirical formula

24 . Define gradient?

It is the rate of rise (or) fall of road level along if length

25.           What are the factors governs the gradient?

(1)characteristics - of the traffic.

(2)Physical factors of the site such a drainage, safety,

Bridge, approach Road and railway Line intersection etc.

26. What are different types of gradient?

(1). Maximum gradient (2). Puling gradient

(3). Limiting gradient (4). Exceptional gradient

27. What are the driaclvantager of Exceptional gradient?

(1). More fuel consumption (2). More friction losses

(3). Efficiency of engine reducer   (4). Early fatigue to animals.

28. What are the hyper of vertical curve?

1. Summit curve  2. Valley curve

29. what is the minimum Radian of vertical curve?

The minimum ration of the curve is given by

L R = ---

Q

30. What is the length of valley curve?

L= 0.38 (NV 3) ½

L = Total Length of valley curve N = Deviation angle

v = Design speed in triumph