### 4. Summary

Trigonometric leveling is a fast efficient way to measure many elevations from a single set up. Being based on a TSI, the process is more flexible than differential leveling.

Whereas in differential leveling the primary instrument is relatively simple, trigonometric leveling depends on a TSI which integrates more measurement types and hence more errors to control. In trigonometric leveling, the surveyor has the option to trade accuracy for productivity depending on the project at hand. Trigonometric leveling does not replace differential leveling but augments it. Differential leveling can be used to build a vertical control network for a project; trigonometric leveling can use that control to collect additional elevation data for design or quantities determination.

Combining trigonometric leveling with horizontal coordinate geometry allows the surveyor to work, design, and implement, in three-dimensions.