Leveling in Surveying
Leveling is the process of measuring vertical distances in surveying. It requires specific instruments for accuracy. Different instruments used for leveling in surveying are dumpy level, Y level, cushing’s level, tilting level, cooke’s reversible level and automatic level.
Types of Levels Used in Surveying
Dumpy Level: A dumpy level is a surveying instrument used to measure the difference in elevation between two points. It consists of a telescope mounted on a tripod, and can be used to measure angles in both vertical and horizontal planes.
Y Level: The Y level is a surveying instrument used to measure vertical angles. It consists of a telescope mounted on a tripod and is used to measure heights, differences in elevation, and angles of inclination.
Cushing’s Level: Cushing’s level is a surveying instrument used to measure differences in elevation between two points. It is a modified form of the dumpy level, and consists of a telescope mounted on a tripod with a spirit level attached to it.
Tilting Level: A tilting level is a surveying instrument used to measure angles of inclination. It consists of a telescope mounted on a tripod, and is used to measure angles in both vertical and horizontal planes.
Cooke’s Reversible Level: Cooke’s reversible level is a surveying instrument used to measure the difference in elevation between two points. It consists of a telescope mounted on a tripod, and is used to measure angles in both vertical and horizontal planes.
Automatic Level Instruments: Automatic level instruments are surveying instruments used to measure vertical distances. It consists of a telescope mounted on a tripod, and is used to measure angles in both vertical and horizontal planes. It is also equipped with a bubble level and digital display for easier readability.
Types of Levels Used in Leveling
Following are the types of different levels used for leveling in surveying:
1. Dumpy Level
Overview of Dumpy Level
Dumpy level is the most widely used instrument in leveling. It consists of a telescope which is fixed to its support and restricted against movement in its horizontal plane. At the top of the telescope, a bubble tube is provided for the purpose of leveling. The telescope is an internal focusing telescope with four main components, namely the objective lens, negative lens, diaphragm, and eyepiece.
Components of Dumpy Level
Objective Lens: The objective lens is the first component of the telescope. It is responsible for collecting and focusing light from the object being viewed.
Negative Lens: The negative lens, also known as the field lens, is the second component of the telescope. It is responsible for controlling the amount of light entering the telescope.
Diaphragm: The diaphragm is the third component of the telescope. It is responsible for controlling the angle of view, as well as the depth of field.
Eyepiece: The eyepiece is the fourth component of the telescope. It is responsible for magnifying the image produced by the other components of the telescope.
Advantages of Dumpy Level
The main advantage of dumpy level is that it is simple and easy to use. It is also relatively inexpensive and does not require any special training or expertise to use. Additionally, it is highly accurate and can be used for precise measurements. Lastly, it is also highly durable, making it an ideal choice for consistent use in a variety of environments.
Objective lens
Objective lenses are made with a combination of crown and flint glass to eliminate optical flaws such as spherical and chromatic aberration. To reduce light reflection, a thin coating with a lower refractive index than the glass is applied to the lens.
Negative Lens
A negative lens is placed co-axially with the objective lens to ensure that both lenses share the same optical axis.
Diaphragm
A diaphragm is fitted inside the main tube which contains two crosshairs (vertical and horizontal) that are adjusted with capstan headed screws. The crosshairs are made of dark metal filaments that are inserted into the diaphragm ring in the correct position. For stadia leveling, two additional horizontal crosshairs are provided above and below the horizontal wire.
Eyepiece Lens: An Essential Tool for Sighting
Eyepiece lenses are an essential tool for sighting an object, offering magnification with cross hairs. This eyepiece lens produces an inverted image. However, certain eyepieces, known as erecting eyepieces, are able to erect the image into a normal view.
2. Y Level
What is a Y-Level?
A Y-level, also known as a Wye-level, is an instrument used for precision measurements and leveling. It is composed of y-shaped frames that support the telescope, which can be removed from the frame by releasing clamp screws. The frames are mounted on a vertical spindle, allowing for quick and easy rotation of the telescope.
Advantages of Y-Levels
Y-levels offer several advantages over Dumpy levels. Adjustments can be made quickly and accurately, allowing for faster and more accurate measurements than with other instruments. Additionally, the open parts of the level are protected from friction and wear, increasing their lifespan.
Disadvantages of Y-Levels
Despite their advantages, Y-levels also have some drawbacks. The open parts of the level are still susceptible to wear, which can lead to decreased accuracy over time. Additionally, the frames can be difficult to adjust, making them more difficult to use than other leveling instruments.
3. Cushing’s Level
CUSHING’S LEVEL TELESCOPE:
Restricted Movement:
The Cushing’s Level telescope is limited in its ability to rotate around its longitudinal axis and is not removable.
Interchangeable and Reversible Components:
The object end and eyepiece end of the Cushing’s Level telescope can be interchanged and reversed.
4. Tilting Level
What is a Tilting Level?
A tilting level is an instrument used for surveying and leveling. It consists of a telescope that is capable of horizontal and vertical rotation, allowing for easy centering of the bubble. This type of level is especially useful when a limited number of observations are to be taken using the same setup.
Benefits of Using a Tilting Level
The main advantage of using a tilting level is that it allows for precise and accurate leveling. With the help of a tilting screw, the bubble can be easily centered to ensure that the readings are accurate. The rotation of the telescope also allows for easy and convenient adjustment of the level’s angle.
Accuracy of Tilting Level
The tilting level is highly accurate and can be used for a variety of surveying and leveling tasks. It is a reliable instrument that ensures accurate readings every time, making it a preferred choice for surveyors and other professionals. With its easy-to-use features, it can be used quickly and efficiently for various applications.
5. Cooke’s Reversible Level
What is Cooke’s Reversible Level?
Cooke’s Reversible Level is a combination of a dumpy level and y-level. It has the unique feature of allowing the telescope to be reversed without rotating the instrument.
How does Collimation Error Elimination take place?
Collimation error elimination takes place in Cooke’s Reversible Level due to the bubble left and bubble right readings of the telescope. This allows the instrument to be used for precise measurements.
6. Automatic Level
Introduction to Automatic Level
An automatic level is a surveying instrument which is similar to a dumpy level. It consists of a telescope which is fixed to its supports, with a circular spirit level attached to the side of the telescope for approximate leveling and a compensator inside the telescope for more accurate leveling.
Features of an Automatic Level
The most important features of an automatic level are its telescope, circular spirit level, and compensator. The telescope is fixed to its supports, allowing for precise leveling and the circular spirit level is attached to the side of the telescope for approximate leveling. The compensator is a device fitted inside the telescope which allows for more accurate leveling.
Benefits of an Automatic Level
The main benefit of an automatic level is its accuracy. The telescope is fixed to its supports and the compensator is fitted inside the telescope ensuring that the device is level and providing precise readings. The circular spirit level is also attached to the side of the telescope, allowing for approximate leveling. This combination of features makes the automatic level a very accurate and reliable instrument for surveying.
Conclusion
The automatic level is a very accurate and reliable instrument for surveying. It consists of a telescope which is fixed to its supports, with a circular spirit level attached to the side of the telescope for approximate leveling and a compensator inside the telescope for more accurate leveling. This combination of features makes the automatic level the ideal surveying tool for precise readings.
What is Compensator?
A compensator, also known as a stabilizer, is an instrument that helps to level automatically. It consists of two fixed prisms that create an optical path between the eyepiece and the objective. The action of gravity causes the optical system to swing into the exact position of the line of sight automatically.
Checking the Compensator
Before the process of leveling can take place, the compensator should be checked. This is to make sure that the optical system is functioning correctly and is ready for the process of leveling. Checking the compensator is an important step in the process of automatic leveling.
How to Check the Compensator in an Automatic Level
Checking the compensator in an automatic level is a relatively straightforward process. To begin, move the foot screws slightly, and observe the reading of the leveling staff. If the reading remains constant, then the compensator is functioning properly. If the reading is not constant, then gently tap the telescope to free the compensator.
Troubleshooting an Automatic Level’s Compensator
If the compensator in an automatic level is not functioning correctly, the first step is to adjust the foot screws. If the reading of the leveling staff remains constant, then the compensator is in working order. If the reading is not constant, then gently tap the telescope to free the compensator.