Reverse curve (surveying)

 

Reverse curve

a. General

A reverse curve consists of two consecutive tangent curves with radius points on opposite sides of the center line. Figure 15 shows basic nomenclature and parts.

Figure D-15 Nomenclature

 

The PRC is the Point of Reverse Curvature, and is the EC of the first curve and BC of the second.

The distance from PI1 to PI2 is T1 + T2. Because of this relationship, as soon as one curve's geometry is fixed, so is the other's. This makes a reverse curve generally easier to compute than a compound curve.

Once the geometry of both curves are fixed, they can be computed as individual simple curves.

b. Stationing

Stationing can be a little confusing since there can be a station equation at both the PRC and EC of the second curve. Usually, if a stationing is maintained along the tangents, then a station equation only appears at the end of the reverse curve.

To compute stationing:

		Equation D-6
		Equation D-7
		Equation D-8
		Equation D-9