Which survey requires the use of a transit and a rod for measuring elevation differences?

The correct answer is the Stadia Survey, as it specifically involves the use of a transit (or theodolite) and a leveling rod (also known as a leveling staff) to determine elevation differences. A Stadia Survey is a method of surveying that employs a transit equipped with a special horizontal reticle that allows the surveyor to measure distances based on the angle subtended by the staff at two points, along with the elevation changes indicated by the leveling rod.

This technique provides both horizontal and vertical measurements, enabling the calculation of elevations relatively straightforwardly while traversing a terrain. The use of the rod in conjunction with the transit facilitates precise elevation readings, which is a defining characteristic of Stadia Surveys.

Other survey types mentioned do not primarily employ a transit and rod for measuring elevation differences. Photogrammetric surveys rely on aerial photographs and photographic analysis rather than direct measurement techniques. A Plane Table Survey uses a plane table for plotting points directly on a sheet while eliminating the need for a transit and rod combination. Total Station Surveys utilize electronic equipment that combines a theodolite with electronic distance measuring capabilities, which typically negates the need for a leveling rod in the same way a Stadia Survey would employ it for elevation measurements.