Engineering Survey Question Answer
1. Why are curves in highway / railway alignment necessary?
During the survey of alignment of a road, railway, canals etc., the direction of the line may change due to some unavoidable conditions. When two straps of a highway or railroad are at some angle from each other, a curve is introduced between them to avoid sudden changes in direction and to make the vehicle run safely, smoothly and comfortably.
2. List of various types of curves. Types of curves:
1. Horizontal Curve - Provided within the horizontal plane.
A. Simple curve
B. Compound curve
C. Reverse curve.
D. Transition curve.
2. Vertical curve - provided where there are two straight lines of different gradient in the vertical plane.
A. Summit curve.
B. The state of greens.
3. What are the three classes of circular curves?
a. Simple curve - consists of a single arc connecting two strips.
b. Compound curve - There are two arcs of different radios bending in the same direction. Center on the same side of the curve. c. Reverse Curve - There are two arcs or different bends of different radius in the opposite direction. Centers occurring on the opposite side of the curve.
4. Determine the degree of curve according to highway practice.
The degree of an arc can be defined based on an arc or cord. By the definition of an arc, the degree of a curve is the central angle connected by an arc of length 30 or 20 m. This arc definition is used in highways.
By cord definition, the degree of a curve is the central angle joined by an arc of length 30 or 20 m. This cord definition is used in railways.
5. Explain the relationship between the radius of a curve and the degree of the curve.
If the chord has a length of 30 m,
R = 1719 / d
If the chord has a length of 20 m,
R = 1146 / d
Where, r = radius of a curve
D = degree of curve
6. What are the weather of an easy circular curve?
1. Back Touch
2. Tangent forward
3. Curve Point (P.C) - T1
4. Tangent Point (P.T) - T2
5. Point of intersection (P.I).
6. Differential angle (I)
7. Deflection angle or central angle (f).
8. Tangent Length
9. Outer Distance or Top Distance
10. Curve Length
11. Long melody. (T1 T2)
12. Middle Coordination
7. Define: Exiting curves (taking curves).
The exit from the curves means the location of different points along the curve and is the same to obtain the actual curves.
8. What methods are used to establish curves?
Methods used to establish curves:
1. Linear Methods.
(I). Offset by long wire.
(Ii). Radial offset from tangent.
(Iii). Vertical offset from tangent
(Iv). Continuous bison of arcs.
(V). Offset from the cord produced.
2. Angular methods.
(I). Rankin? Method of deflection angle. (A theodolite method)
(Ii). Two- Theodolite method.
(Iii). Tachometric method.
9. What is the sight distance in highways? What factors affect if?
The moving distance can be defined as the minimum distance between two vehicles Along a curve, when the driver of one vehicle can see another vehicle ahead on the road.
Factors affecting vision distance are:
(I). Height of driver's line of sight
(Ii). Grade or longitudinal slope of the curve
(Iii). vehicle speed
(Iv). coefficient of friction
(V). Pause capability.
10. What is meant by stopping the distance of vision?
This is the minimum distance required for the safe movement of traffic within which the driver of the vehicle is moving at design speed. After reaching the presence of a threat ahead, you can stop it before reaching any danger.
It depends
(I). Grade or longitudinal slope of the curve
(Ii). vehicle speed.
(Iii). coefficient of friction
(Iv). Pause capability.
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