What is the primary function of a vertical curve?

The primary function of a vertical curve is to connect two vertical tangents. Vertical curves are used in roadway design to create a smooth transition between different grades or slopes, enhancing driver comfort and vehicle performance. By connecting two vertical tangents—where one slope changes to another via a curve—these transitions help to maintain safety and visibility. This smooth transition is crucial for vehicle dynamics, particularly in preventing abrupt changes in elevation that could lead to unsafe conditions.

Additionally, vertical curves are critical for ensuring proper sight distances, which allow drivers to see ahead on an incline or decline effectively. The design of these curves takes into account factors such as speed limits and vehicle types to determine the appropriate radius and length, ultimately improving the overall road experience for motorists.