What is the main purpose of using a transit level in grading operations?

The main purpose of using a transit level in grading operations is to establish elevations. This instrument provides precise measurements of the height of land and helps ensure that the grading work is completed according to design specifications. By accurately determining elevations, the transit level allows operators to achieve proper drainage, slope, and contouring of the land.

Establishing elevations is crucial in grading because it sets the foundation for any subsequent construction activities. An accurate elevation ensures that structures are built on stable and level ground, thereby preventing issues related to drainage and structural integrity later on.

The other options are not directly related to the primary function of a transit level in grading. Compaction of soil, measurement of soil density, and determination of soil moisture involve different tools and techniques that focus on different aspects of site preparation. These tasks may support the overall grading process but do not fall within the realm of elevation measurement that transit levels are designed for.