Which type of leveling does not require a backsight?

Indirect leveling is a method that does not require a backsight, which is essential in other leveling techniques. This form of leveling typically involves calculating elevations indirectly, often utilizing a combination of known data points and mathematical methods rather than relying on direct observation between benchmark points.

In indirect leveling, engineers may use techniques such as trigonometric leveling, where the heights are determined based on angles and distances rather than direct measurements from a leveling instrument. This approach is particularly useful in scenarios where traditional backsight methods may be impractical due to sight obstructions or other field conditions.

Consecutive leveling, direct leveling, and geodetic leveling all rely on the concept of backsights to establish a reference point for determining differences in elevation. Therefore, while those methods are valuable for establishing and verifying levels over short and extended distances, indirect leveling provides a flexible alternative in situations where backsights cannot be easily established.