In roadway terminology, what does a tangent line signify?

A tangent line in roadway terminology refers specifically to a straight line that touches a curve at precisely one point without crossing it. This definition is crucial in the context of road design and geometric alignment. When designing roads, the concept of tangent lines is applied in the transition from straight sections to curves, ensuring smooth vehicle movement and safety.

A tangent helps to provide a clear understanding of the road's alignment at the point where a curve begins, indicating an instantaneous direction of travel. This is essential for drivers as it provides a visual indication of changes in direction, facilitating smoother navigation through curves.

Utilizing tangent lines in engineering ensures that the design of the roadway adheres to safe operating speeds and helps determine the necessary superelevation (banking of roads) for curves, enhancing overall road safety and driver comfort.