# Summit Curve

**Problem**

A +0.8% grade meets a -0.4% grade at km 12 + 850 with elevation 35 m. The maximum allowable change in grade per station is 0.2%. Determine the length of the curve.

A. 300 m | C. 80 m |

B. 240 m | D. 120 m |

## Problem 04 - Symmetrical Parabolic Curve

**Problem**

A highway engineer must stake a symmetrical vertical curve where an entering grade of +0.80% meets an existing grade of -0.40% at station 10 + 100 which has an elevation of 140.36 m. If the maximum allowable change in grade per 20 m station is -0.20%, what is the length of the vertical curve?

A. 150 m

B. 130 m

C. 120 m

D. 140 m

## Parabolic Curve

**Vertical Parabolic Curve**

Vertical curves are used to provide gradual change between two adjacent vertical grade lines. The curve used to connect the two adjacent grades is parabola. Parabola offers smooth transition because its second derivative is constant. For a downward parabola with vertex at the origin, the standard equation is

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