Which of the following is a reason for establishing benchmarks in surveying?

Establishing benchmarks in surveying is crucial primarily because they serve as fixed elevation references. This is essential for various surveying tasks, including the leveling of land, determining slope gradients, and establishing a consistent vertical datum for future measurements. Benchmarks allow surveyors to ensure that their measurements are accurate and reliable over time and across different locations.

Referencing fixed elevation points helps in avoiding discrepancies that can arise due to ground movement, errors in measurement, or changes in the terrain. A benchmark provides a stable point from which all other elevations can be measured, which is essential for large-scale projects like construction, infrastructure development, and land surveying.

While vehicle safety, project timelines, and road traffic calculations are significant aspects of civil engineering and project management, they do not directly relate to the primary function of benchmarks in surveying. Benchmarks are specifically about establishing consistent and accurate height readings which support the surveying process.