# Crest vertical curve length

A crest vertical curve is a feature on a road or highway that allows for a smooth transition between grades, or inclines, on the road. The length of the crest vertical curve is important for ensuring the safety of drivers and vehicles, as well as providing a comfortable driving experience.

To calculate the length of a crest vertical curve, there are several factors that need to be taken into account. These include the design speed of the road, the stopping sight distance, and the elevation of the road at the crest of the curve.

One of the most commonly used methods for calculating the length of a crest vertical curve is the parabolic method. This method uses the formula L = (V²)/(127R) to determine the length of the curve, where L is the length of the curve, V is the design speed of the road, and R is the radius of the curve.

Another method that can be used to calculate the length of a crest vertical curve is the sag vertical curve method. This method uses the formula L = (V²)/(32g) to determine the length of the curve, where L is the length of the curve, V is the design speed of the road, and g is the acceleration due to gravity.

In addition to these methods, there are also several online calculators and software programs available that can be used to calculate the length of a crest vertical curve. These calculators and software programs typically require input of the design speed of the road, the stopping sight distance, and the elevation of the road at the crest of the curve.

Overall, the length of a crest vertical curve is an important consideration in the design of roads and highways. Proper calculation of the length of the curve can help to ensure the safety and comfort of drivers, as well as the longevity of the road.