Surveying Instruments: Types, Properties & Uses
There are a variety of surveying instruments that can be used to measure angles and elevations. It is important to carefully select the best instrument for the job. Sources of information for the instrument can be found in the product manuals or catalogs provided by the manufacturer.
Choosing the Best Instrument
When selecting the best instrument for measuring angles and elevations, a few factors should be taken into consideration. These include accuracy, durability, portability, and cost. It is also important to understand the features and capabilities of the instrument and how it will be used. This will help to ensure that the instrument is suitable for the specific purpose.
Equipment Used for Measuring Angles and Elevations in Surveying
The common equipment used for measuring angles and elevations in surveying are:
- Hand level
- Abney level
- Dumpy level
- Automatic level
- Laser level
- Transit
- Theodolite
Hand Levels for Measurement of Elevation and Slope in Surveying
What is a Hand Level?
A hand level is a simple surveying instrument used to ensure that the chains are in level when measuring horizontal distance with the help of plumb bobs. It is also used for slope estimation and change in elevation. The common magnification of hand level is from zero to 5x.
How Does a Hand Level Work?
Hand levels work by using a spirit level and a single cross-hair. The spirit level is used to ensure that the chains are in level when the horizontal distance is measured with the help of plumb bobs. The single cross-hair allows for slope estimation and change in elevation. More sophisticated hand levels may also have stadia hairs to measure the horizontal distance.
How to Use a Hand Level to Estimate Elevation and Slope
The hand level is an ideal tool for measuring elevation and slope. To use it effectively, first stand at the bottom of the slope and hold the hand level in a horizontal position. Then observe where the line of sight strikes the ground, and mark this point. By measuring the distance to this point and the height of the user’s eye from the ground, you can accurately determine the slope of the terrain.
% slope = (Rise/Run) x 100
- Measurement of Eye Height (Rise):
The eye height of the user is the rise, which can be measured in order to determine the distance between the observation point and where the line of sight strikes the ground. - Measuring Distance (Run):
The run or the distance from the observation point to where the line of sight strikes the ground can be measured by pacing. - Low Precision of Measuring Distance:
The result of measuring distance by pacing is found to have low precision, as the measured distance is the sloped distance and not the horizontal distance.
Abney Level for Measurement of Angles and Slope in Surveying
What are Abney Levels?
Abney levels are a type of hand level that offer more sophistication and precision. They feature a direct-reading scale for vertical angles and slope, as well as stadia hairs and improved optics and magnification. Abney levels are more precise than regular hand levels, as the stadia hairs have a precision of 1/10 of a foot. Additionally, they have provisions for adjustment for both focusing and magnification. When used with a rod and target, Abney levels provide excellent accuracy for preliminary surveying.
How Abney Levels Differ from Hand Levels
The main difference between Abney levels and hand levels is the precision they offer. Abney levels have a direct-reading scale for vertical angles and slope, as well as stadia hairs that measure a distance of 1/10 of a foot with precision. This makes them more accurate than regular hand levels. In addition, Abney levels have provisions for adjusting both focusing and magnification, allowing for greater accuracy when using a rod and target.
1. Improving Accuracy of Measurement with a Stick and Levels Using a stick of known height together with a hand level and an Abney level can help to improve the accuracy of measurement. By holding the stick in place, it helps to keep the level steady and can allow for more precise readings. This can be especially useful when measuring heights and depths, as the stick can provide a reference point to ensure a consistent level of accuracy.
Dumpy Level for Measurement of Angles and Elevation in Surveying
What is a Dumpy Level?
A dumpy level is a simple, accuracy-enhanced instrument used for surveying and leveling operations. Supported by a tripod, the dumpy level consists of a telescope and a spirit level mounted parallel to the line of sight of the telescope. The telescope features at least one horizontal cross hair mounted in line with the line of sight, in addition to a vertical cross hair and two stadia cross hairs.
Benefits of Using a Tripod
Using a tripod with a dumpy level helps to improve the accuracy of measurements. Additionally, the tripod serves as a reference for horizontal angles, making it easier to measure accurately.
Features of a Dumpy Level
The dumpy level features a telescope and a spirit level. The telescope has at least one horizontal cross hair mounted in line with the line of sight, as well as a vertical cross hair and two stadia cross hairs. With these components, the dumpy level is useful for surveying and leveling operations.
Leveling Plate
The leveling plate is a rotating mechanism that can turn 360 degrees. This platform is used to mount the telescope and the spirit level, which is necessary for surveying. The leveling plate is attached to a tripod and is leveled to begin the surveying process.
Mounting the Telescope and Spirit Level
The telescope and spirit level are mounted onto the leveling plate for surveying. This plate is designed to rotate 360 degrees and can be leveled on the tripod to begin the surveying process.
Surveying with the Leveling Plate
The leveling plate is used to start the surveying process. The telescope and spirit level are mounted on the plate and the whole mechanism is leveled on the tripod. This allows for accurate surveying results to be obtained.
Automatic Level for Measurement of Angles and Elevation
What is an Automatic Level?
An automatic level is a surveying tool that is used to establish and maintain a horizontal line of sight. It is typically used in construction and engineering to ensure that the ground is level or that a structure is built on a flat surface. This instrument is equipped with an internal compensator that compensates for small movements within the instrument and keeps the line of sight in level.
How Does an Automatic Level Work?
An automatic level utilizes an internal compensator that helps to keep the line of sight in the horizontal position. Once the instrument is nearly level, the compensator completes the leveling process. This allows the instrument to maintain the horizontal line of sight throughout the surveying process.
What are the Benefits of an Automatic Level?
Using an automatic level offers several benefits when completing surveying tasks. By utilizing an internal compensator, the instrument is able to maintain accuracy and precision in the surveying process. This allows for more accurate results and a higher level of accuracy than manual leveling. Additionally, the use of an automatic level allows the surveyor to work more quickly and efficiently.
What is an Internal Compensator?
An internal compensator is a feature present in automatic levels that helps maintain the instrument’s accuracy and level of precision. It ensures that any slight bumps or vibrations caused by wind are compensated and the instrument is not knocked out of level.
How is an Automatic Level Different from a Dumpy Level?
Automatic levels make use of a bull’s eye spirit level for leveling, instead of the more traditional tube level used in dumpy levels. Additionally, automatic levels require only three leveling screws to be used for leveling instead of the four used in dumpy levels, making the setup process faster. Automatic levels are less accurate and precise than transits and total stations, but more accurate than dumpy levels.
What Types of Automatic Levels are Available?
A variety of models of automatic levels are available to suit various needs. Some models are more accurate and precise than others, so it is important to select the one that best suits your particular requirements.
Laser Level for Measurement of Angles and Elevation
Types of Laser Levels
A laser level is a measuring tool that utilizes a beam of laser light to establish a reference line. There are several types of laser levels available, including single beam invisible, single beam visible, circular beam visible, and circular beam invisible.
Single Beam Invisible
Single beam invisible laser levels feature a single dot or a short line. This type of laser level is used to ensure that the reference line is perfectly straight and accurate.
Single Beam Visible
Single beam visible laser levels are similar to single beam invisible laser levels, but they produce a visible beam of light instead of a single dot or short line. This type of laser level is useful for tasks that require a visible reference line.
Circular Beam Visible
Circular beam visible laser levels are capable of producing a 360-degree beam of light. This type of laser level is ideal for large-scale projects and tasks that require a visible reference line over a large area.
Circular Beam Invisible
Circular beam invisible laser levels are similar to circular beam visible laser levels, but they produce an invisible beam of light instead of a visible beam. This type of laser level is useful for tasks that require an invisible reference line.
Advantage of Using a Laser Level
The primary advantage of using a laser level is that a single person can operate the system. The laser level is mounted on a tripod and then leveled, and then no further supervision is required. This allows surveyors to record rod readings while moving around the area, staying within the range of the laser beam. Additionally, multiple detectors can be used with a single laser level, making it possible for more than one person to record data simultaneously.
Transit Level for Measurement of Angles and Elevation
What is a Transit Level?
A transit level is an instrument used to measure the relative position of lines and objects in a given area. It consists of a telescope with a built-in spirit level that is mounted on the spirit level. The transit level is highly accurate, and is mainly used for surveying and building. It is used to establish a reference line for further measurements.
Benefits of Using a Transit Level
Transit levels offer several benefits for measuring lines and objects. It provides a highly accurate measurement, which is essential for surveying and building. It also makes it easier to establish a reference line for further measurements. Additionally, it is relatively easy to use and portable, making it suitable for a wide range of applications.
Applications of a Transit Level
Transit levels are mainly used for surveying and building. They can be used to measure the elevation and distances of points, as well as the angle of lines. They can also be used to measure the height of a building or other structure. Additionally, they can be used to set up a reference line for further measurements.
Theodolite for Measurement of Angles in Surveying
What is a Theodolite?
A theodolite is an instrument used for measuring angles in the horizontal and vertical planes. It is most commonly employed in surveying, but is also used in metrology and rocket launch technology. The theodolite contains a movable telescope mounted on two axes, the horizontal trunnion axis and the vertical axis. This enables it to accurately measure angles with the help of a forced centering plate or tribrach.
Components of a Theodolite
A theodolite is made up of a number of components. The telescope is the main component, mounted on two perpendicular axes. It is held in place with a forced centering plate, often referred to as a tribrach, which is attached to the tripod head. The tribrach consists of four thumbscrews in the case of older theodolites and three or four rapid leveling screws in modern models.
Uses of a Theodolite
Theodolites are used in a variety of different applications. The most common use is in surveying, where it is used to accurately measure angles in the horizontal and vertical planes. Theodolites are also used in metrology and rocket launch technology. In both cases, the theodolite is used to accurately measure angles and distances. The telescope enables it to accurately point at a target, and the forced centering plate ensures accuracy and stability.
Step 1: Positioning the Theodolite
The first step in using a theodolite is to position the instrument correctly. This requires the theodolite to be placed vertically above the point to be measured. This can be achieved with the help of a plumb bob, optical plummet, or laser plummet.
Step 2: Leveling the Theodolite
Once the theodolite is correctly positioned, it needs to be leveled. This is done by adjusting the leveling foot screws and tubular spirit bubbles. This ensures that the theodolite is perfectly level and ready for use.