What does the tangent offset in a vertical curve indicate?

The tangent offset in a vertical curve refers to the vertical distance between the grade line (the line representing the road or railway alignment) and the curve itself. It is a critical aspect of vertical alignment, particularly when designing roadways or railways, as it helps to define how steeply or gently a vertical curve transitions from one grade to another. By measuring this offset, engineers can ensure that the curve meets safety and design standards, providing a smooth transition for vehicles while maintaining proper drainage and sight distances.

The other options refer to different concepts within vertical curves or road design but do not accurately represent what the tangent offset entails. The highest point of the curve relates more to the curve’s apex rather than the offset itself. The length of the curve and the slope comparison to the terrain are distinct measures that do not directly correlate with the definition of tangent offset. Understanding the tangent offset is essential for achieving effective and safe roadway design.