18.2. Valley curve

Try these first

1. 1.

   What is a valley curve?

   Hint

   Think about how roads change elevation.

2. 2.

   Name one type of gradient that can form a valley curve.

   Hint

   Consider which ways the road can slope.

3. 3.

   What is a valley curve?

   • A curve with an upward slope
   • A curve with a downward slope
   • A straight line

   Hint

   Think about the term 'sag' associated with valley curves.

4. 4.

   True or False: Valley curves are not necessary for road design.

   • True
   • False

   Hint

   Consider the purpose of transitions in road design.

5. 5.

   Given a valley curve formed by a descending gradient of n=1 in 25 and an ascending gradient of n=1 in 30, calculate both stopping sight distance and the length of the valley curve. Assume a safe design speed of 80 km/h.

   Hint

   Apply comfort and safety criteria formulas to find both conditions.

6. 6.

   Discuss the ramifications of not accounting for headlight sight distance when designing valley curves, and provide examples of potential issues.

   Hint

   Think about situations where low visibility can cause danger.