A curve which consists of a two circular arcs of same or different radii having their centers to the different sides of the common tangent is called a________.
reverse curve
Understanding Curve Types in Surveying and Road Design
The question asks to identify a specific type of curve used in various engineering applications, particularly surveying and road design. The curve is described as consisting of two circular arcs with certain characteristics regarding their radii and the position of their centers relative to a common tangent.
Let's analyze the definition provided: "A curve which consists of a two circular arcs of same or different radii having their centers to the different sides of the common tangent".
Now, let's consider the given options:
- simple curve
- compound curve
- transition curve
- reverse curve
We will examine the characteristics of each curve type to determine which one matches the description.
Simple Curve
A simple curve is the most basic type, consisting of a single circular arc connecting two tangents. It has a constant radius throughout its length. This does not fit the description of two circular arcs.
Compound Curve
A compound curve consists of two or more circular arcs joined end to end, curving in the same direction. The consecutive arcs have different radii, and they share a common tangent at their junction point (Point of Compound Curvature or PCC). The centers of the arcs are located on the same side of the common tangent. This does not match the description of centers being on different sides of the common tangent.
Transition Curve
A transition curve (also known as a spiral curve) is used to provide a gradual change in curvature between a tangent section and a circular curve, or between two circular curves of different radii. Its radius changes gradually along its length, typically from infinite (at the tangent) to the radius of the circular curve. This does not fit the description of two distinct circular arcs with centers on different sides of a common tangent.
Reverse Curve
A reverse curve consists of two circular arcs curving in opposite directions. The two arcs are joined at a common tangent point (Point of Reverse Curvature or PRC). The centers of the two circular arcs lie on opposite sides of this common tangent. The radii of the two arcs can be the same or different. This description perfectly matches the definition provided in the question: two circular arcs, same or different radii, centers on different sides of the common tangent.
Based on the definitions, the curve described is a reverse curve.
| Curve Type | Description | Centers Relative to Common Tangent |
|---|---|---|
| Simple Curve | Single circular arc | N/A (single arc) |
| Compound Curve | Two or more circular arcs in the same direction | Same side |
| Transition Curve | Gradually changing radius (spiral shape) | N/A (gradual transition) |
| Reverse Curve | Two circular arcs in opposite directions | Different sides (opposite sides) |
Conclusion on Curve Definition
The question defines a specific type of curve used to change direction, characterized by two circular arcs bending in opposite directions with centers on different sides of a shared tangent. This description uniquely identifies a reverse curve.
Revision Table: Understanding Curves
| Term | Key Characteristic |
|---|---|
| Simple Curve | Single arc, constant radius |
| Compound Curve | Multiple arcs, same direction, different radii |
| Transition Curve | Gradual radius change, connects tangent to curve or curve to curve |
| Reverse Curve | Two arcs, opposite directions, common tangent, centers on opposite sides |
Additional Information on Reverse Curves
Reverse curves are sometimes used in situations with limited space, such as railway sidings or very low-speed roads. However, they require careful design and execution, especially on highways or railways with higher speeds, because the instantaneous change in curvature at the Point of Reverse Curvature (PRC) can cause discomfort to passengers and introduce dynamic forces on the vehicle. To mitigate this, transition curves are often inserted between the circular arcs and the common tangent point in high-speed applications, converting the true "reverse curve" into a setup involving tangents, transition curves, and circular curves.
Key points about reverse curves:
- They are suitable for low-speed applications.
- They involve a sudden reversal of curvature at the common tangent point.
- The radii of the two arcs can be equal or unequal.
- The centers of the two arcs are on opposite sides of the common tangent.
Important Questions from Curves
The difference in length between the arc and the subtended chord on the earth's surface is taken as 500mm in:
The length of a simple circular curve of radius R meters and deflection angle D degrees will be
The angle of intersection of a curve is the angle between the
The shift of a circular curve is given by __________
Where,
L = Length of transition curve and R = Radius of the circular curve
The point where the alignment changes from a straight line or tangent to a circular curve is called as-
