25.7 : Design Example: Maintaining Level of an Embankment

Constructing a roadway embankment over uneven terrain requires precise leveling to ensure stability and proper drainage. Surveyors use a leveling instrument and staff to calculate ground elevations and determine the required fill material at each point along the embankment alignment.

The process begins by positioning a leveling instrument near a benchmark with a known elevation. A backsight reading establishes the instrument height, which serves as a reference for subsequent measurements. A foresight reading is then taken on the leveling staff at the first point along the alignment to measure the difference in elevation. Sequential backsight and foresight readings are repeated to create a profile of ground elevations.

The required fill material at each location is calculated by subtracting the measured ground elevation from the target embankment height, set at 3 meters. If the leveling instrument is moved, the last calculated point is used as a temporary benchmark to re-establish the instrument height at the new position.

This systematic process ensures the embankment follows the intended height and gradual slope, preventing drainage and stability issues. Adhering to these methods guarantees accurate elevation control, enabling the embankment to meet design and safety standards.