25.2
Leveling Equipment
As leveling involves measuring vertical distances relative to a horizontal line of sight, it requires a graduated rod, called a level rod, for vertica…
The primary tools used for leveling are a level and a level rod.
A level consists of a telescope for focusing on the object to be sighted and a spirit level and leveling screws for leveling the instrument.
Automatic levels and electronic digital levels are generally used for accurate leveling.
The automatic level fixed on the tripod, after being roughly leveled manually, uses a suspended compensator for automatic and precise leveling of the instrument.
An electronic digital level also performs automatic leveling and is designed to take readings electronically by sighting the bar codes provided on the level rod.
A level rod is a graduated rod made of wood, fiberglass, or metal that comes in one or more pieces.
The graduations start from zero at the bottom and are represented in feet or meters, depending on the region.
The readings on the level rod are sighted and read through the level's telescope.
Sometimes, a sliding vernier scale placed on the rod or an optical micrometer mounted on the telescope helps take readings smaller than the rod's least count.
View the full transcript and gain access to JoVE Core videos
Q1: What are the main components of a level used in surveying?
A level consists of a telescope for focusing on objects, a spirit level bubble for centering, and leveling screws for manual adjustment. Automatic levels use a suspended compensator for precise automatic leveling after rough manual setup. Electronic digital levels perform automatic leveling and take readings electronically by sighting bar codes on the level rod.
Q2: What materials and graduations are used for level rods?
Level rods are graduated rods made of wood, fiberglass, or metal, available in one or more pieces that fold or slide together. Graduations start from zero at the bottom and are represented in feet or meters depending on the region. The rod's sole has a metal plate for durability, and readings are sighted through the level's telescope.
Q3: How do automatic levels differ from electronic digital levels?
Automatic levels use a suspended compensator to automatically orient the line of sight once roughly leveled with leveling screws and a circular spirit level. Electronic digital levels function similarly with a pendulum compensator for optical leveling but also process bar-code rod images electronically to measure distances and compute point elevation with one-button operation.
Q4: What methods improve reading accuracy on a level rod?
A sliding vernier scale placed on the rod or an optical micrometer mounted on the telescope helps take readings smaller than the rod's least count. These precision tools allow surveyors to obtain measurements more accurate than the rod's basic graduations, improving the overall accuracy of leveling measurements.
Q5: Why is a horizontal line of sight essential for leveling?
Leveling measures vertical distances relative to a horizontal line of sight, requiring the level's telescope to establish a truly horizontal reference. The spirit level bubble and leveling mechanism ensure the line of sight remains horizontal when centered, which is critical for accurate vertical distance measurements in surveying applications.
Q6: What alternative instruments can be used as levels in surveying?
Beyond automatic and electronic digital levels, laser levels, tilting levels, total stations, and transit theodolites can be used as levels for surveying work. Each instrument offers different capabilities and precision levels depending on project requirements and field conditions encountered during surveys.
Q7: How does a high-powered telescope function in a leveling instrument?
The level's high-powered telescope focuses on the level rod to enable precise sighting and reading of graduations from a distance. The telescope magnifies the rod's markings, allowing surveyors to accurately read vertical measurements and detect small variations in elevation across surveying projects.