How many connected curves comprise a compound curve?

A compound curve is defined by the geometric construction where two or more simple circular curves are connected to each other, allowing for a smooth transition between differing radii. In general, a compound curve consists of at least two circular arcs, but it can contain more depending on the design requirements.

Typically, a compound curve will consist of at least three distinct arcs, particularly when discussing standard engineering practices. The first arc might connect to the second arc, and the second connects to a third, creating a smooth flow that is essential for road design or rail layouts.

The concept of a compound curve is crucial in alignment design, as it directly impacts the transition of vehicles between different curves, thereby affecting safety and comfort. Each additional arc could further enhance the smoothness of the transition, but at a minimum, three arcs are standard for a compound curve setup. This is why the correct response aligns with the definition and application of compound curves in engineering contexts.