The Surveying Equipment industry has many different types of tools, each with its own benefits. One important consideration is Surveying Errors, which can impact the accuracy of the data collected.
One of the most important types of surveying equipment is a laser scanner. This scanner produces 3D data and works alongside traditional surveying equipment, such as a total station. Surveyors use it to collect large amounts of data quickly and efficiently. The scanner generates data called a point cloud, which surveyors interpret using CAD software, building information modeling, or geographic information system software.
Surveyors use the chain to measure distance on the ground, and it provides more accuracy than a tape.
A chain consists of connecting links of galvanized mild steel, each 20 cm in diameter. The ends of the chain are provided with swivel joints, allowing the surveyor to move the chain to the precise position. Depending on the purpose of the measurement, the chain can be as long as 20 meters or even more.
Total Station
Another type of surveying equipment is a total station. This device has a pointing head, which is a circular box. In the middle of the octagon are two slits, one for the end of the line, and one for the beginning. The angular misclose is a common method used to prove that the work was done properly and accurately. In some cases, a total station is the most convenient option when working with a wide variety of materials.
It can transmit and receives positioning data, acts as the control hub for GPS accuracy on a site and can be used to measure distances or angle measurements, and can even be used to mark buildings and other structures. While there are a lot of different types of surveying equipment, there are a few that are essential for every project. The size of the site will determine the number of base stations that are needed.
Disto Laser Measurer
A Disto laser measurer is a tool that uses a laser to measure distances. The device is ideal for measuring in difficult to reach locations. The angular difference between the first and final bearing is the close. The first and last bearing will differ, and this angular difference will show that the survey is not correct. The angular misclose will tell the surveyor whether the work has met standards. These two measurements are a good example of a good survey.
Among the most important surveying instruments is theodolites, it measure angles in the horizontal and vertical planes. Its accuracy is high, making it ideal for topographic surveys. It has many advantages, but is still expensive compared to other surveying tools. So, if you are interested in land surveys, theodolite is an essential tool for you. Once you have it, you can use it anywhere and anytime.
Types of Surveying Errors
Measurements are never exact and regardless of the survey instrument or method used, there will always be a degree of variance. These variances are known as errors and will need to be reduced or eliminated to maintain specific survey standards. It is important for the surveyor to understand the different types of errors in order to minimize them.
1. Mistakes:
Mistakes are errors which arise from inattention, inexperience, carelessness and poor judgment or confusion in the mind of the observer. They do not follow any mathematical rule (law of probability) and may be large or small, positive or negative. They cannot be measured. However, they can be detected by repeating the whole operation. If a mistake is undetected, it produces a serious effect upon the final result. Hence, every value to be recorded in the field must be checked by some independent field observation.
2. Accidental Errors:
This type of error can occur due to unavoidable circumstances like variations in atmospheric conditions which are entirely beyond the control of the observer. Errors in surveying due to imperfection in measuring instruments and even imperfection of eyesight fall in this category. They may be positive and may change sign. They cannot be accounted for.
3. Systematic or Cumulative Errors:
A systematic or cumulative error is an error that, under the same conditions, will always be of the same size and sign. A systematic error always follows a definite mathematical or physical law, and we can determine and apply the necessary correction. These errors remain constant and appear as positive or negative, depending on whether they increase or decrease the result. Therefore, their effect accumulates. For example, if a tape is P cm short and we stretch it N times, the total error in measuring the length becomes P × N cm.
The systematic errors may arise due to (i) variations of temperature, humidity, pressure, current velocity, curvature, refraction, etc. and (ii) faulty setting or improper leveling of any instrument and personal vision of an individual.
4. Compensating Errors:
This type of surveying error tends to occur in both directions, i.e. the error may sometimes tend to be positive and sometimes negative thereby compensating each other. They tend sometimes in on direction and sometimes in the other, i.e. they are equally likely to make the apparent result large or small.
How to avoid errors during a surveying task
Surveying errors may be negligible, or at times they might be significant. Besides, the goal of any survey is to produce accurate and precise observations. Often measurements with greater accuracy and precision requirements employ multiple observations to minimize procedural errors.
In order to avoid errors, surveyors need to calibrate their equipment before they start the survey. The best way to do this is to use consistent methods and a good reference network. This will ensure that the measurements that are made on site are accurate. For example, using a Disto laser measurer to survey an area will save time, and Ground penetrating radar will save a lot of chain-measurement.
Key Areas to Avoid Errors
According to Chris Muya, Managing Director at Measurement Systems Limited, the following are the key areas a surveyor should put into much consideration to avoid errors:
1) The Surveyor should check the accuracy of the control points.
If the control points the surveyor is using for site calibration are faulty, then the work itself will have errors. The control points should be verified by the Government Survey Office.
2) The machine being used should be calibrated and checked for errors before the work.
Calibration mostly happens for total stations and level machines. The errors that are most common with such machines are distance errors, bearing errors, laser errors, leveling bubble errors among others.
3) The surveyor should have a good understanding of the machines in use.
For example, while using RTK, there are different solutions the surveyor should look out for; float solution and fixed solution. A fixed solution occurs when the receiver calculates the correct result, while a float solution occurs when the algorithm has not yet solved, making it less accurate.
4) In the case of booking, the surveyor should verify the information they are writing down to reduce booking errors.
5) The surveyor uses modern survey equipment configured to deliver the highest accuracy and consults their dealer if the machine requires a firmware upgrade.
Product Specification and Training
Additionally, “Defining proper product specification and training to establish complying to the requirement,” is another important aspect as indicated by Alwyn Coetsee, Director at Turner Morris (Pty) Ltd.
Aside from surveying instrument, surveyors also use other kinds of equipment and accessories which includes ancillary equipment accessories like tripods, instrument stands, and staves, personal protective gear, vegetation clearing devices, and hammers for placing survey markers.
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