What Is a Traverse?
A traverse is a series of connected lines whose lengths and directions must be measured. The process of surveying to find these measurements is known as traversing.
Measuring Lengths and Directions of Traverse Lines
Chains are often used to measure length, while a theodolite or compass is used to measure the direction of traverse lines.
Types of Traverse and Methods of Traversing
There are various types of traverse and methods of traversing. These include open traverse, closed traverse, and radial traverse. Each type of traverse has its own methods and techniques that must be followed to obtain accurate measurements.
Types of Traverse
A Traverse may be of two types. Namely,
- Open Traverse
- Closed Traverse
1. Open Traverse
What is an Open Traverse?
An open traverse is a survey technique used to measure distances between two points. It involves measuring a series of connected lines that start at one point and end at another. This type of traverse is also known as an unclosed traverse and is typically used for surveying roads, coastlines, and other linear features.
How to use an Open Traverse?
Using an open traverse involves measuring angles and distances between points and connecting those points with a series of straight lines. The angles and distances are recorded in a surveyor’s field book and later used to create a map of the area surveyed. A surveyor will typically use a theodolite, a surveyor’s level, and a rangefinder to accurately measure the angles and distances.
Advantages of an Open Traverse
Open traverses are a useful survey tool since they allow surveyors to measure distances between two points without having to traverse back over the same lines. This type of survey is also fairly easy to set up and requires minimal equipment. Additionally, an open traverse can be used to connect two points that may be far apart, making it a great tool for surveying large areas.
2. Closed Traverse
What is a Closed Traverse?
A closed traverse is a type of survey that forms a closed circuit. It starts and ends at the same point, making it suitable for surveying boundaries of areas such as ponds, sports grounds, and forests.
Benefits of a Closed Traverse
A closed traverse has the benefit of eliminating the need to plot and calculate the end point from the beginning point. It also reduces the risk of errors in measurements, as the measurements taken to close the traverse are compared with each other. This ensures accuracy in the survey results.
Methods of Traversing
Types of Surveying Traversing
Surveying traversing is a method of measuring the position of a series of points on the surface of the earth. This method is used to obtain the relative positions of a number of points, which form a closed circuit of lines. Here, we discuss the four different methods of surveying traversing.
Chain Traversing
Chain traversing is the simplest and oldest method of surveying. It is a method of linear measurement using a chain or tape. This method is used to measure the distances between two points.
Compass Traversing
Compass traversing is a method of surveying based on the use of a compass for angular measurements. This method is used to measure the angles between two points.
Theodolite Traversing
Theodolite traversing is a method of surveying which involves the use of a theodolite instrument to measure vertical and horizontal angles and distances. This method is used to measure the angles, directions and distances between two points.
Plane Table Traversing
Plane table traversing is a method of surveying which uses a plane table to measure angles and distances. This method is used to measure the angles, directions and distances between two points.
1. Chain Traversing
What is Chain Traversing?
Chain traversing is a surveying technique which involves taking linear measurements only, using a chain or tape. It is mainly used in areas such as ponds or other difficult-to-access areas, where triangulation cannot be used. This technique involves establishing the angle between the adjacent traverse lines using the chain angles concept.
How Does Chain Traversing Work?
Chain traversing works by using the chain angles concept to measure the angle between two adjacent sides. This angle can be determined either by establishing a chord of known length between the sides or by setting up tie stations to establish the third side. Once the angle between the sides is measured, the measurements of the other sides can be calculated.
Benefits of Chain Traversing
Chain traversing is a useful surveying method which has several benefits. It is relatively easy to use and does not require complex mathematical calculations. It is also more efficient than triangulation and can be used in areas which are difficult to access. Furthermore, it is accurate and reliable and can be used to measure angles with precision.
2. Compass Traversing
What is Compass Traversing?
Compass Traversing is a surveying technique used to measure both linear and angular measurements of traverse lines. In this technique, a chain is used to measure linear distances, while a prismatic compass is used to measure angular measurements. The two bearings taken for each traverse line are known as the fore bearing and the back bearing. Corrections for local attraction are applied to the measurements taken.
How to Adjust Closing Errors?
In the case of compass traversing, if any closing error is obtained while plotting the traverse, then the Bowditch rule is applied to adjust the error. The Bowditch rule is a mathematical technique used to determine the magnitude and direction of the closing error, so that the error can be corrected.
3. Theodolite Traversing
Theodolite Traversing: Linear and Angular Measurements
Theodolite traversing is a surveying technique that combines linear and angular measurement methods for accurate results. For linear measurements, the chain or stadia method is used. Angular measurements are taken using a theodolite, which measures the magnetic bearing of the first traverse line. By taking this initial measurement, the magnetic bearings of all other sides can be calculated. This method is highly accurate in comparison to other surveying techniques.a
4. Plane Table Traversing
Introduction to Plane Table Traversing
Plane table traversing is a surveying method which involves the measuring and plotting of a traverse on the paper simultaneously. This method is used to determine the relative position of two points or traverse stations in a clockwise or anti-clockwise direction.
Setup of Plane Table Equipment
The plane table equipment is set up at each traverse station one by one. The sides of each traverse station are then drawn to a suitable scale on paper.
Adjustment of Closing Errors
If there is any closing error, graphical methods are used to make the necessary adjustments.
