Vertical alignment of a roadway primarily considers which two factors?

Vertical alignment in roadway design focuses on how the road changes in elevation as it progresses. This involves defining the elevation of the road at different points and ensuring that these elevations are appropriately matched with the physical features surrounding the road and the requirements for vehicle operations.

The correct answer highlights that the factors of elevation and horizontal distances are crucial. Elevation is critical because it determines how steep or gentle the road will be at different sections, directly affecting vehicle performance, safety, and drainage. Horizontal distances come into play as they relate to the geometry of the roadway; they determine how the elevation changes occur over space, leading to smoother transitions and safer designs.

This interplay between elevation changes and the distances over which they occur ensures a well-designed vertical alignment that enhances the road's safety and usability. Understanding these relationships is central to effective roadway design and engineering practices, as they affect sight distance, vehicle dynamics, and overall roadway comfort for users.