Instruments Used in Chain Surveying
Chain surveying is a widely used method in land surveying that involves the measurement of distances and angles using a chain and various other instruments. In this blog post, we will discuss the key instruments used in chain surveying and their importance in ensuring accurate measurements.
The chain is the primary instrument used in chain surveying. It consists of a series of interconnected links that are typically made of steel. The chain is used to measure distances between various points on the land. It is available in different lengths, such as 20 meters, 30 meters, and 50 meters, depending on the requirements of the survey.
Tapes are commonly used as an alternative to chains in modern chain surveying. They are made of steel or fiberglass and are available in various lengths. Tapes are more flexible and lightweight compared to chains, making them easier to handle and carry. They provide accurate measurements and are particularly useful in areas with uneven terrain.
Arrows are used to mark the survey points on the ground. They are typically made of wood or metal and have a sharp end that can be easily inserted into the ground. Arrows are essential for accurately locating the points that need to be measured. They are also useful in marking the starting and ending points of the chain or tape.
4. Ranging Rods
Ranging rods are used to establish straight lines during the survey. They are typically made of wood or metal and are painted in bright colors for better visibility. Ranging rods are placed at different points along the survey line, and the surveyor uses them as reference points for measuring distances and angles. They help in maintaining the accuracy of the survey by ensuring that the survey line is straight.
5. Offset Rods
Offset rods are used to measure perpendicular distances from the survey line. They are typically made of wood or metal and have markings at regular intervals. Offset rods are placed at right angles to the survey line, and the surveyor uses them to measure the distance from the survey line to various objects or features on the land, such as buildings, trees, or boundaries.
A peg is a wooden or metal stake used to mark survey points on the ground. It is driven into the soil to establish reference points for measurements. Pegs are crucial in maintaining the accuracy and consistency of the survey.
7. Plumb Bob
A plumb bob is a weighted object attached to a string. It is used to determine vertical alignment during the survey. By observing the position of the plumb bob, surveyors can ensure that measurements are taken along the vertical axis.
8. Plasterer’s Laths
Plasterer’s laths are thin strips of wood or metal used to mark the survey line. They are placed at regular intervals along the chain to maintain a straight line during the survey. These laths act as visual aids for surveyors, ensuring the accuracy of measurements.
White is a marking material used to make temporary markings on the ground. It can be in the form of white paint or chalk. Surveyors use white to mark points, lines, and boundaries during the survey. These markings are easily visible and help in accurate measurement and mapping.
A clinometer is a device used to measure angles of inclination or slope. In chain surveying, a clinometer is used to measure the slope of the terrain. This information is vital for calculating elevations and determining the topography of the surveyed area.
Advantages of Chain Surveying
Chain surveying is a widely used method in land surveying due to its numerous advantages. In this blog post, we will explore the key benefits of chain surveying and why it is a preferred choice for many surveyors.
1. Simplicity and Cost-Effectiveness
One of the main advantages of chain surveying is its simplicity. The equipment required for chain surveying is minimal, consisting primarily of a chain, ranging rods, and pegs. This simplicity makes it a cost-effective method, as it does not require expensive instruments or advanced technology.
Despite its simplicity, chain surveying can provide accurate results when performed correctly. The use of a chain allows for precise measurements of distances, ensuring the reliability of the survey data. This accuracy is crucial for various applications, such as mapping, boundary determination, and construction planning.
Chain surveying is a versatile method that can be used in different terrains and environments. It is particularly suitable for small-scale surveys, such as land subdivisions and property boundaries. The flexibility of chain surveying allows surveyors to adapt to various field conditions and obtain accurate measurements.
4. Ease of Learning and Execution
Compared to other surveying methods, chain surveying is relatively easy to learn and execute. It does not require extensive training or technical expertise, making it accessible to both experienced surveyors and beginners. The straightforward procedures involved in chain surveying contribute to its popularity and widespread use.
5. Historical Significance
Chain surveying has a long history and is deeply rooted in the field of surveying. It is considered one of the oldest surveying techniques and has been used for centuries to measure and map land. Its historical significance adds to its credibility and trustworthiness as a reliable surveying method.
Disadvantages of Chain Surveying
Chain surveying is a popular method used in land surveying due to its simplicity and cost-effectiveness. However, like any surveying technique, it has its limitations and disadvantages. In this blog post, we will discuss some of the main disadvantages of chain surveying.
1. Limited Accuracy
One of the major disadvantages of chain surveying is its limited accuracy. The accuracy of chain surveying is highly dependent on the skill and experience of the surveyor. Even with the most skilled surveyor, errors can occur during the measurement and recording of distances and angles. These errors can accumulate and result in significant deviations from the true measurements.
Chain surveying can be a time-consuming process, especially when working on large or complex surveying projects. Each distance and angle measurement needs to be carefully taken and recorded, which can be a time-consuming task. Additionally, the process of setting up and moving the chain and other surveying equipment can also take up a significant amount of time.
3. Prone to Errors
Chain surveying is prone to various types of errors. For example, errors can occur due to the stretching or sagging of the chain, temperature variations that affect the length of the chain, and human errors in reading and recording measurements. These errors can significantly impact the accuracy of the surveying results and lead to incorrect land measurements.
4. Not Suitable for Rough Terrain
Chain surveying is not suitable for rough or uneven terrain. The chaining process requires a clear and unobstructed path between the survey points. In areas with dense vegetation, steep slopes, or other obstacles, it can be challenging to accurately measure the distances and angles using a chain. In such cases, other surveying methods, such as theodolite surveying or aerial surveying, may be more suitable.
5. Limited Scope
Chain surveying has a limited scope and is best suited for small-scale surveying projects. It is not suitable for large-scale projects that require high levels of accuracy and precision. For large-scale projects, more advanced surveying techniques, such as GPS surveying or laser scanning, are often used.
These are some of the essential instruments used in chain surveying. Each instrument plays a crucial role in ensuring accurate measurements and creating detailed maps. By using these instruments correctly, surveyors can produce reliable data that is essential for various engineering and construction projects.
FAQs on Instruments Used in Chain Surveying
Chain surveying is a widely used method for measuring distances and creating accurate maps. It involves the use of various instruments to ensure precise measurements. In this article, we will answer some frequently asked questions about the instruments used in chain surveying.
1. What is a chain in chain surveying?
A chain is a measuring tape made up of metallic links. It is used to measure distances in chain surveying. The most commonly used chain is the Gunter’s chain, which is 66 feet long and divided into 100 links.
2. What is a ranging rod?
A ranging rod is a long pole with a pointed end. It is used to mark points and align the chain during surveying. Ranging rods are typically made of wood or metal and are painted in alternating colors for better visibility.
3. What is a cross staff?
A cross staff is a simple instrument used for setting out right angles. It consists of two perpendicular arms that are fixed at the center. The cross staff is used to measure right angles and set up perpendicular lines during chain surveying.
4. What is a theodolite?
A theodolite is a more advanced instrument used in chain surveying. It is used to measure horizontal and vertical angles. The theodolite consists of a telescope mounted on a tripod, with a graduated circle and vernier scale for accurate angle measurements.
5. What is a prismatic compass?
A prismatic compass is used to measure magnetic bearings or azimuths. It consists of a magnetic needle, a prism, and a graduated circle. The compass is used to determine the direction of a line or to measure the angle between two lines.
6. What is an optical square?
An optical square is an instrument used to set out right angles. It consists of a square prism with a horizontal and vertical crosshair. The optical square is used to establish perpendicular lines and right angles during chain surveying.
7. What is a leveling staff?
A leveling staff is a long rod marked with graduated divisions. It is used in leveling operations to measure vertical distances. The staff is held vertically and the measurements are taken using a leveling instrument such as a dumpy level or a theodolite.
8. What is a plumb bob?
A plumb bob is a weight attached to a string. It is used to determine vertical lines and to ensure that surveying instruments are properly aligned. The plumb bob is hung from the instrument and the string is used as a reference for vertical measurements.
These are some of the commonly used instruments in chain surveying. Each instrument plays a specific role in ensuring accurate measurements and precise mapping. It is important for surveyors to be familiar with these instruments and their functions to conduct successful chain surveys.