Several essential equipment are used in levelling surveying. These include:
- Level Instrument: The level instrument is the primary tool used in levelling surveys. It typically consists of a telescope mounted on a tripod. The telescope is equipped with a horizontal spirit level and a vertical crosshair to ensure proper alignment. The instrument allows surveyors to measure the height differences between points accurately.
- Levelling Staff: The levelling staff is a graduated rod used to measure the vertical distances during levelling surveys. It is held upright at the points where elevation measurements are taken. The staff is marked with precise divisions or graduations, usually in metric or imperial units, which allow for accurate readings.
- Tripod: The tripod is used to support and stabilize the level instrument. It is adjustable in height and allows the surveyor to position the instrument at the desired height and level it properly. The tripod’s legs are typically made of sturdy materials such as aluminum or wood to ensure stability during measurements.
- Staff Bubble: The staff bubble, also known as a leveling vial or bull’s eye level, is a small spirit level attached to the levelling staff. It helps the surveyor ensure that the staff is held vertically upright during measurements, which is crucial for accurate readings.
- Plumb Bob: A plumb bob is a weighted metal or brass object attached to a string. It is used to establish a vertical reference line or to check the verticality of the levelling staff. The plumb bob hangs freely, and its vertical alignment helps in ensuring accurate vertical measurements.
- Field Book and Pencil: A field book is used to record all the necessary data and observations made during the levelling survey. It includes information such as backsight readings, foresight readings, intermediate point readings, and any relevant notes. A pencil or pen is used to make the entries in the field book.
- Measuring Tape: A measuring tape is used to measure the horizontal distances between survey points. Although not specifically for levelling, it is often needed to determine the positioning of the levelling instrument and to measure distances between survey stations.
These are some of the essential equipment used in levelling surveying. Each instrument plays a crucial role in obtaining accurate height measurements and ensuring the overall success of the survey.
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