What is a benchmark in surveying?

A benchmark in surveying is fundamentally understood as a fixed point with a known elevation. This definition is pivotal because benchmarks serve as reference points that surveyors use to establish the elevation of various terrains and constructions. They are typically marked physically in the field, often through markers like brass disks or concrete monuments, and must be easily identifiable and reliably stable over time.

The significance of using a fixed point with a known elevation lies in its crucial role in determining height differences and ensuring accuracy in construction and land surveying. By starting measurements from a benchmark, surveyors can maintain a consistent reference which aids in leveling and grading, providing a foundation for all subsequent elevation measurements in the project.

Benchmarks are fundamental in various surveying tasks, including determining the topography of a site, setting levels for roads, and managing drainage systems, making the knowledge of their application essential for anyone involved in highway construction inspection or surveying.