A total station is an advanced measuring instrument that combines an electronic theodolite with an electronic distance meter (EDM) to measure angles and distances. It is widely used in surveying, construction, and civil engineering projects. In this comprehensive guide, we’ll explore everything you need to know about total stations, from their history to their modern-day applications. We’ll discuss the components of a total station, how it works, and its various uses in different industries.
Introduction
In the past, surveying and measuring land was a tedious and time-consuming task. But with the advent of technology, the process has become more efficient and accurate. Total station is a sophisticated surveying instrument used to measure distance, angles, and coordinates of points on the earth’s surface. It integrates a theodolite, an electronic distance measurement (EDM) system, and a microprocessor with a display panel. A total station is one such technology that has revolutionized the surveying and construction industry.
What is a total station survey?
A total station survey is a precise and advanced surveying technique used in the fields of civil engineering, construction, land surveying, and geomatics. It combines the functions of an electronic theodolite (a device for measuring horizontal and vertical angles) with those of an electronic distance meter (EDM) to collect highly accurate measurements of angles and distances on the earth’s surface.
History of the Total Station (TS)
The total station was first introduced in the 1970s. It quickly gained popularity due to its ability to measure angles and distances accurately. The early versions of total stations used manual recording methods, which were time-consuming and prone to errors. But with the advent of electronic data recording, total stations became more accurate and efficient.
Types of Total Station
Total stations come in different types, each designed for specific surveying tasks. Some of the most common types of total stations include:
- Electronic Total Stations: Electronic total stations are the most common type of total station. They use electronic distance meters (EDMs) to measure distances, and digital levels to measure elevations. They can also be connected to a computer to store and analyze survey data, making them efficient and accurate.
- Robotic Total Stations: Robotic total stations are similar to electronic total stations, but they are operated remotely using a remote control or a computer. They are often used in areas where access is limited or dangerous, such as construction sites or mining areas.
- Reflectorless Total Stations: Reflectorless total stations are used for surveying in areas where reflectors cannot be used, such as in dense forests or in urban areas with high-rise buildings. They use a laser beam to measure distances and can operate over long distances.
What are the parts of total station?
A TS consists of several components, including an electronic theodolite, EDM, microprocessor, electronic display, and a data collector. The electronic theodolite is used to measure horizontal and vertical angles, while the EDM is used to measure distances between the TS and the target. Total Stations are composed of four primary components: Electronic Distance Measurement (EDM), theodolite, microprocessor, and display panel.
- Electronic Theodolite: The electronic theodolite is the part of the total station that measures horizontal and vertical angles. It is mounted on a tripod and can be rotated in any direction.
- Electronic Distance Meter: The electronic distance meter is the part of the total station that measures distances between points. It uses a laser beam to determine the distance between the total station and the point being measured.
- Microprocessor: The microprocessor is the part of the total station that processes and stores the data collected by the electronic theodolite and the electronic distance meter.
- Display Unit: The display unit is where the data collected by the total station is displayed. It shows the angles, distances, and elevations measured by the electronic theodolite and the electronic distance meter.
- Battery: The battery is the power source for the total station.
How Total Station Works?
A total station works by emitting a laser beam towards the target, which reflects back to the total station. The EDM then calculates the distance between the total station and the target, while the theodolite measures the angles. The microprocessor then calculates the coordinates of the target based on the angle and distance measurements.
- Line of Sight: The Total Station works by establishing a line of sight between the instrument and the target. The line of sight is the imaginary straight line that connects the instrument to the target. The instrument’s ability to establish a clear line of sight is crucial to obtaining accurate measurements.
- Angle Measurements: The theodolite measures the horizontal and vertical angles between the instrument and the target. The instrument’s accuracy in measuring angles is essential to achieving precise survey measurements.
- Distance Measurement: The EDM system measures the distance between the instrument and the target. The EDM system’s accuracy depends on the instrument’s quality and the reflectivity of the target surface.
What are the applications of total station?
Total Stations are used in a variety of fields, including:
- Land Surveying: Total Stations are widely used in land surveying to measure angles, distances, and coordinates of points on the earth’s surface. Land surveyors use Total Stations to create maps, establish boundaries, and prepare construction plans.
- Construction: Total Stations are used in the construction industry to layout building foundations, locate building corners, and determine site elevations.
- Archaeology: Total Stations are used in archaeological excavations to create site maps, determine the location of artifacts, and record excavation data.
- Forensic Investigations: Total Stations are used in forensic investigations to document crime scenes accurately, record measurements, and create diagrams.
- Environmental Management: Total stations are used in environmental management to measure and monitor natural resources, such as water, soil, and vegetation. They can also be used to create accurate maps of environmental features, such as wetlands, forests, and coastlines.
What is the advantage of total station?
Total Stations offer several advantages over traditional surveying methods, including:
- High Accuracy: Total Stations are highly accurate and can measure angles and distances with precision.
- Time-Saving: Total Stations can perform measurements quickly and accurately, saving time and effort.
- Easy to Use: Total Stations are easy to operate, and they require minimal training to use effectively.
- Remote Control Capability: Total Stations can be operated remotely, allowing surveyors to measure points that are difficult to reach or in hazardous locations.
- Versatile: Total stations can be used for a variety of applications, including surveying, construction, and mapping.
What is the Disadvantages of Total Station
Total Stations have some limitations, including:
- Costly: Total Stations are expensive, and their high cost may be a barrier to entry for some surveyors.
- Requires Skill and Training: Total Stations require skill and training to operate effectively. Surveyors must have a solid understanding of surveying principles, the instrument’s components, and how to use the instrument.
- Limited Range of Operation: Total Stations have a limited range of operation, and their accuracy decreases over longer distances.
Maintenance and Care of the Total Station
TS require regular maintenance and care to ensure optimal performance. Some maintenance tips include:
- Regular Cleaning: Clean the instrument after each use to prevent dust and debris from accumulating on the lenses and affecting the measurements.
- Proper Storage: Store the instrument in a dry, cool place to prevent damage to the lenses and electronic components.
- Battery Care: Charge the batteries fully before using the instrument and replace the batteries regularly to ensure optimal performance.
How do you conduct a total station survey?
Conducting a total station survey involves a series of steps to accurately measure angles and distances on the earth’s surface using a total station instrument. Here is a general overview of how to conduct a total station survey:
Step 1: Preparation:
- Site Assessment: Begin by assessing the survey site. Determine the boundaries and extent of the area to be surveyed. Identify any existing benchmarks or control points that can serve as reference for your survey.
- Instrument Setup: Set up the total station on a stable tripod at a known reference point. Ensure that the tripod is level using a leveling bubble and secure the instrument tightly to prevent movement.
- Calibration: Calibrate the total station if necessary. This includes ensuring that the instrument is correctly aligned and its internal settings are adjusted for accurate measurements.
Step 2: Target Placement:
- Prism or Reflector Placement: Place a target, such as a prism or reflector, on the point you want to survey. Ensure that the target is firmly attached and visible from the total station.
Step 3: Instrument Operation:
- Instrument Setup: Power on the total station and initialize it. Set the appropriate measurement units (e.g., degrees or gon) and measurement modes (e.g., angle and distance).
- Pointing and Aiming: Use the total station’s eyepiece or digital display to sight and aim the instrument at the target. Ensure that the crosshairs of the instrument are aligned with the center of the target.
- Measure Horizontal Angle: Capture the horizontal angle between the total station and the target by pressing the appropriate button on the instrument. The total station will display the measured angle.
- Measure Vertical Angle: Similarly, measure the vertical angle by tilting the total station’s telescope up or down and capturing the angle.
- Measure Distance: Activate the electronic distance meter (EDM) on the total station to measure the distance to the target. The total station will emit a signal (e.g., laser or infrared) to the target, which reflects the signal back to the instrument. The total station calculates the distance based on the signal’s travel time.
Step 4: Data Collection:
- Recording Data: Record the measured horizontal and vertical angles, as well as the distance, in your data collector or field notebook. You can also include additional information such as point labels and descriptions.
- Repeat for Multiple Points: To create a survey of multiple points, repeat the aiming and measurement process for each point of interest. Ensure that you maintain visibility between the total station and the target.
Step 5: Data Processing:
- Data Reduction: After completing the field survey, transfer the collected data to specialized surveying software for processing. The software can perform calculations, generate maps, and create reports based on the survey data.
Step 6: Quality Control:
- Check for Errors: Review the survey data for any errors or inconsistencies. Verify that measurements are accurate and that all necessary points have been surveyed.
Step 7: Reporting:
- Generate Reports: Use the processed data to generate survey reports, drawings, or maps as needed for your project. These reports can include details about distances, angles, elevations, and other relevant information.
Conducting a total station survey requires precision, attention to detail, and proper instrument handling. It’s essential to follow established surveying procedures and ensure that the instrument is correctly calibrated and leveled to obtain accurate measurements. Additionally, maintaining clear line-of-sight between the total station and the target is crucial for successful surveying.
Why use total station survey?
Total station surveys are used for several reasons in various fields, including land surveying, construction, civil engineering, and geomatics, due to their many advantages and capabilities. Here are some key reasons why total station surveys are commonly used:
- High Precision: Total stations are known for their high precision in measuring angles and distances. They provide accurate and reliable data, making them essential for applications where precision is crucial, such as land boundary surveys, construction layout, and engineering design.
- Efficiency: Total stations significantly increase surveying efficiency. They can quickly capture angle and distance measurements for multiple points, reducing the time required for fieldwork compared to traditional surveying methods.
- Data Integration: Total stations integrate electronic theodolites with electronic distance meters (EDMs). This combination allows for the simultaneous measurement of angles and distances, streamlining the data collection process and reducing the risk of errors.
- Real-Time Measurements: Total stations provide real-time measurements, allowing surveyors to instantly verify data quality and accuracy in the field. This capability is especially valuable for construction layout and quality control tasks.
- Versatility: Total stations can be used for a wide range of surveying tasks, including topographic mapping, boundary surveys, construction staking, deformation monitoring, and more. Their versatility makes them suitable for various applications within the fields of geomatics and engineering.
- 3D Modeling: Total stations can be used to create detailed 3D models of surveyed areas or objects. These models are valuable for design, visualization, and analysis purposes in architecture and civil engineering projects.
- Remote Measurement: Total stations can measure distances to reflective targets, including prisms, at considerable distances. This capability is useful for large-scale surveys or measurements in challenging terrain.
- Improved Documentation: Total station surveys provide accurate and comprehensive documentation of surveyed areas. This documentation can be used for legal purposes, property management, and facility maintenance.
- Cost Savings: By increasing surveying efficiency and accuracy, total stations can lead to cost savings in terms of reduced labor and resources required for fieldwork. Additionally, they help minimize the potential for costly errors and rework.
- Safety: Total station surveys often involve minimal physical labor and exposure to hazardous conditions, improving safety for surveyors working in the field.
- Environmental Benefits: The efficiency of total station surveys can reduce the environmental impact associated with traditional surveying methods, such as the need for extensive fieldwork and transportation of heavy equipment.
- Data Integration with GIS: Total station data can be integrated with Geographic Information Systems (GIS), allowing for seamless integration of survey data with geographic databases and spatial analysis.
What are the errors in total station?
Total stations are sophisticated surveying instruments capable of high precision, but like any measurement device, they are subject to various errors and sources of inaccuracies. Understanding these errors is crucial for surveyors and engineers to ensure accurate results. Here are some common errors associated with total station measurements:
Instrumental Errors:
- Scale Factor Error: Total stations use electronic distance meters (EDMs) to measure distances. Scale factor error can occur due to variations in the refractive index of the atmosphere, which affects the speed of light. Instruments often apply a correction factor to account for this error.
- EDM Calibration: Inaccuracies in the EDM calibration can lead to distance measurement errors. Regular calibration and maintenance are essential to minimize this error.
Angular Errors:
- Index Error: Index error refers to errors in the horizontal and vertical circles of the total station’s theodolite. It can result from misalignment or calibration issues and must be corrected for precise angle measurements.
- Collimation Error: Collimation error occurs when the line of sight of the total station is not perfectly aligned with the horizontal or vertical axis. This error can affect both horizontal and vertical angle measurements.
Atmospheric Conditions:
- Refraction: Refraction of light in the atmosphere can cause apparent shifts in target positions, especially over long distances. Surveyors often apply atmospheric corrections to mitigate this effect.
- Temperature and Pressure: Variations in temperature and atmospheric pressure can affect the speed of light and, consequently, distance measurements. Instruments may include corrections for these factors.
Target Issues:
- Prism Offset: If the prism used as a target is not properly calibrated or mounted with its center at the surveyed point, it can introduce errors in distance and angle measurements.
- Prism Displacement: If the prism is not set at the exact height above the ground that the instrument expects, vertical angle measurements can be inaccurate.
Multipath Interference:
- Multipath interference occurs when the measurement signal from the total station reflects off nearby surfaces or objects before reaching the target. This can result in incorrect distance measurements.
Instrument Setup:
- Errors in leveling the total station or ensuring its proper alignment with the surveying datum can introduce both horizontal and vertical angle errors.
Human Errors:
- Surveyors can introduce errors through manual data input, incorrect targeting, misinterpretation of instrument readings, and errors in instrument setup.
Environmental Conditions:
- Adverse weather conditions, such as rain, fog, or extreme temperatures, can affect the performance of the total station, leading to measurement errors.
Geometric Dilution of Precision (GDOP):
- GDOP refers to the geometric configuration of satellites in the Global Navigation Satellite System (GNSS) constellation. Poor satellite geometry can lead to less accurate position determinations when combining GNSS and total station measurements.
Systematic Errors:
- Systematic errors can arise from consistent biases in measurements and may require the application of correction factors based on calibration and testing.
To mitigate errors in total station measurements, surveyors employ various strategies, including regular instrument calibration and maintenance, applying correction factors, using high-quality prisms and targets, and carefully considering the environmental and geometric conditions at the survey site.
Conclusion
Total Stations are essential surveying instruments used in a variety of fields, including land surveying, construction, archaeology, and forensic investigations. They offer several advantages, including high accuracy, time-saving, and ease of use.
However, they also have some limitations, including their high cost, the need for skill and training, and their limited range of operation. Proper maintenance and care of the instrument are necessary to ensure optimal performance and longevity.
FAQs
What is the difference between a total station and a theodolite?
A total station is an advanced measuring instrument that combines an electronic theodolite with an electronic distance meter (EDM) to measure angles and distances. A theodolite is an optical instrument used for measuring horizontal and vertical angles.
Which wave is used in total station?
Total stations use electromagnetic waves in the form of infrared light for distance measurements and angle measurements.
These waves are typically in the range of 600-900 nm wavelength, which falls in the near-infrared part of the electromagnetic spectrum.
How accurate are total stations?
The accuracy of a total station depends on several factors, including the quality of the instrument, atmospheric conditions, and the experience of the operator. Most total stations have an accuracy of up to 1/16th of an inch.
Can total stations be used in remote areas?
Total stations require a clear line-of-sight to the target, which can be difficult in remote areas. In contrast, GPS can measure distances from satellite signals, making it more suitable for remote areas.
What kind of training is required to use a total station?
Using a total station requires specialized training, as it involves knowledge of surveying principles, electronic equipment, and data collection. Many vocational schools and colleges offer courses in surveying and total station operation.
What is the future of total station technology?
The future of total station technology looks promising, with continued advancements in electronic equipment and data collection. With the integration of cloud computing and real-time data processing, total stations will become more efficient and faster. Additionally, the use of total stations in emerging technologies such as autonomous vehicles and drones will increase.
What is the maximum range of a total station?
Total stations with advanced EDM systems can measure distances up to 10 kilometers or more, but accuracy may decrease with distance due to atmospheric distortion and target surface reflectivity.
What is ppm in total station?
PPM “parts per million” is a unit of measurement used in Total Stations to represent the maximum allowable deviation in angle measurements. It is an important specification to consider when selecting a Total Station as it affects the precision and accuracy of measurements taken.
Higher PPM values indicate greater accuracy but also come with a higher price tag.
For example, if a Total Station has a PPM of 2, it means that for every million parts of a measurement, there can be a maximum deviation of 2 parts.
