Sight distance
Sight distance asks a practical question: after the driver notices a hazard, is there enough distance to understand, react, brake, or avoid it?
Image source: The road on the mountain (Unsplash).jpg, Unsplash License, used here as a mountain road and vertical alignment reference.
| Type | Purpose | Sensitive locations |
|---|---|---|
| Stopping sight distance | Can the driver stop in time? | Crests, sharp curves, tunnel portals |
| Meeting sight distance | Can two-way traffic pass safely? | One-lane bridges, temporary roads |
| Passing sight distance | Is overtaking feasible? | Long tangents, gentle grades |