Vertical grade
Vertical grade is the most direct indicator in the road profile. It affects climbing performance, downhill braking, drainage, earthwork, and how far the driver can see.
Image source: The road on the mountain (Unsplash).jpg, Unsplash License, used here as a mountain road and vertical alignment reference.
| Scenario | Concern | Editor suggestion |
|---|---|---|
| Long upgrade | Power demand and speed loss | Lower grade or lengthen alignment |
| Long downgrade | Stopping distance and braking heat | Reduce continuous grade length |
| Near a crest | Stopping sight distance | Lengthen vertical curve |
| Tunnel portal or bridge end | Drainage, visibility, structural tie-in | Avoid abrupt grade change |