What factor is MOST critical to remember regarding vertical control points?

Vertical control points are crucial in surveying as they provide reference elevations for various points on the earth's surface. Their primary purpose is to ensure that elevation measurements are accurate and consistent, which is vital for construction projects, land development, and any activities where elevation plays a significant role.

Establishing a network of vertical control points allows surveyors to relate the elevations of various points to a common reference standard, often tied to sea level or another known datum. This is especially important when precise measurements are needed, such as grading, drainage design, or any project where elevation changes could impact functionality and safety.

In contexts where only horizontal distances are of concern, vertical control points may not seem immediately relevant. However, it is important to recognize that even horizontal surveys can benefit from known elevations, especially when considering the terrain's influence on measurements and design. Therefore, the critical factor is the essential role of vertical control points in ensuring precise elevation measurements, as they form the foundation for all further elevation-related work in surveying and engineering.