The curve that is generally used to avoid the obstructions like hard rocks, deep cuttings, soft gradients is called:
- Asimple curve
- Btransitional curve
- Ccompound curveCorrect
- Dparabolic curve
Solution
Concept
A compound curve is made of two or more simple arcs of different radii that bend in the same direction. It helps the alignment pass around obstacles.
Step-by-step solution
1. A simple curve has a single radius, so it cannot easily fit around obstacles. 2. A compound curve joins arcs of different radii in the same direction. 3. Changing the radius lets the route avoid hard rock, deep cutting or bad ground. 4. So the answer is the compound curve.
Explanation
A compound curve uses two or more arcs of different radii that turn in the same direction. Because the radius can change, the alignment can go around obstructions like hard rock or deep cuttings. This is why it is used in difficult ground.
Why the other options are wrong
A: A simple curve has only one radius and gives little flexibility around obstacles. B: A transition curve gives a gradual change of curvature for comfort and superelevation, not obstacle avoidance. D: A parabolic curve is mainly used as a vertical curve on gradients.
Shortcut
Avoid obstruction by changing radius = compound curve.
Common mistake
Choosing the transition curve, which is used for gradual change of curvature and not for avoiding obstacles.
Correct answer: C) compound curve