CST Level 1 Land Surveyor Certification Practice

What is a Point of Intersection (PI) defined as?

1. A point where vertical curves meet

2. The midpoint of a horizontal curve

3. Point of Intersection of incoming and outgoing tangents of a horizontal Curve

4. A point of tangency in circular arcs

The correct answer is: Point of Intersection of incoming and outgoing tangents of a horizontal Curve

A Point of Intersection (PI) is defined as a critical geometric feature in horizontal curve design. Specifically, it is the location where the incoming tangent line intersects the outgoing tangent line of a horizontal curve. This point is essential in the design of roadways and railways as it signifies the transition where the curvature begins and ends. Understanding this concept is crucial for land surveyors as it informs the construction and alignment of courses. The other options describe related but distinct concepts within the domain of curve geometry. For instance, the meeting of vertical curves refers to where changes in grade occur but does not pertain to horizontal curvature specifically. The midpoint of a horizontal curve and a point of tangency in circular arcs refer to different aspects of curve design that do not define a PI. Therefore, recognizing the PI’s definition as the intersection of tangents helps clarify its integral role in surveying and roadway design.