Use of Tacheometry for Traversing and Contouring

Introduction

Tacheometry is an important technique used in surveying for various applications, including traversing and contouring. It involves the use of a tacheometer, which is an advanced surveying instrument that combines the features of a theodolite and a stadia rod. Tacheometry allows surveyors to measure both horizontal and vertical distances with high accuracy and efficiency.

In this article, we will explore the use of tacheometry for traversing and contouring, discussing the fundamentals, steps involved, real-world applications, and advantages and disadvantages of this technique.

Use of Tacheometry for Traversing

Traversing is a surveying technique used to establish control points and measure the angles and distances between them. Tacheometry plays a crucial role in traversing by providing accurate measurements and reducing the time required for fieldwork.

The following are the steps involved in using tacheometry for traversing:

1. Setting up the instrument: The tacheometer is set up on a tripod at a known control point.
2. Taking observations: The surveyor aims the instrument at the next control point and measures the horizontal and vertical angles using the telescope and the stadia hairs.
3. Calculation of angles and distances: The observed angles and stadia readings are used to calculate the horizontal and vertical distances between the control points.
4. Plotting the traverse: The measured distances and angles are plotted on a traverse sheet to create a graphical representation of the survey.

Here is an example problem to illustrate the use of tacheometry for traversing:

Example Problem: A surveyor is conducting a traverse using tacheometry. The horizontal angle between two control points is measured as 50°, and the vertical angle is measured as 2°. The stadia reading on the rod is 1.5 m. Calculate the horizontal and vertical distances between the control points.

Solution: To calculate the horizontal distance, we can use the formula:

$$D = S \times k \times cos(\theta)$$

Where:

• D is the horizontal distance
• S is the stadia reading
• k is the stadia constant
• $$\theta$$ is the horizontal angle

Similarly, the vertical distance can be calculated using the formula:

$$V = S \times k \times sin(\theta)$$

By substituting the given values into the formulas, we can calculate the horizontal and vertical distances.

Use of Tacheometry for Contouring

Contouring is a surveying technique used to determine the elevation of points on the ground and create contour lines, which represent the shape and slope of the terrain. Tacheometry is widely used in contouring due to its ability to provide accurate elevation measurements.

The following are the steps involved in using tacheometry for contouring:

1. Setting up the instrument: The tacheometer is set up on a tripod at a known control point.
2. Taking observations: The surveyor aims the instrument at various points on the ground and measures the vertical angles using the telescope and the stadia hairs.
3. Calculation of elevations and contours: The observed vertical angles and stadia readings are used to calculate the elevations of the points and determine the contour lines.
4. Plotting the contours: The calculated elevations and contour lines are plotted on a contour map to visualize the terrain.

Here is an example problem to illustrate the use of tacheometry for contouring:

Example Problem: A surveyor is conducting contouring using tacheometry. The vertical angle between a control point and a point on the ground is measured as 3°, and the stadia reading on the rod is 1.2 m. Calculate the elevation of the point.

Solution: To calculate the elevation, we can use the formula:

$$E = H + (S \times k \times sin(\theta))$$

Where:

• E is the elevation
• H is the height of the instrument
• S is the stadia reading
• k is the stadia constant
• $$\theta$$ is the vertical angle

By substituting the given values into the formula, we can calculate the elevation of the point.

Real-world Applications and Examples

Tacheometry has various real-world applications in surveying, including:

• Use of tacheometry for road construction: Tacheometry is used to establish control points, measure angles and distances, and create cross-sections for road construction projects.
• Use of tacheometry for building construction: Tacheometry is used to determine the positions and elevations of building corners, ensuring accurate construction.
• Use of tacheometry for land surveying: Tacheometry is used to survey large areas of land and create topographic maps.
• Use of tacheometry for topographic mapping: Tacheometry is used to measure the elevations of points on the ground and create detailed topographic maps.

Advantages and Disadvantages of Tacheometry

Tacheometry offers several advantages over traditional surveying methods, including:

1. Faster and more efficient than traditional methods: Tacheometry allows surveyors to measure angles and distances quickly, reducing the time required for fieldwork.
2. Suitable for rough and inaccessible terrains: Tacheometry can be used in terrains where traditional methods are difficult to implement, such as dense forests or steep slopes.
3. Provides accurate and precise measurements: Tacheometry provides high accuracy and precision in measuring angles, distances, and elevations.

However, tacheometry also has some disadvantages, including:

1. Requires skilled personnel to operate the instrument: Tacheometry requires trained surveyors who are familiar with the instrument and its calculations.
2. Limited range of measurement compared to other methods: Tacheometry has a limited range of measurement compared to other surveying methods, such as GPS.
3. Susceptible to errors due to atmospheric conditions: Tacheometry measurements can be affected by atmospheric conditions, such as haze or heat shimmer.

Conclusion

Tacheometry is a valuable technique in surveying, particularly for traversing and contouring. It allows surveyors to accurately measure angles, distances, and elevations, making it essential for various applications in construction, land surveying, and mapping. By understanding the fundamentals, steps involved, and real-world applications of tacheometry, surveyors can effectively utilize this technique to achieve accurate and efficient results.

Summary

Tacheometry is an important technique used in surveying for traversing and contouring. It involves the use of a tacheometer, which combines the features of a theodolite and a stadia rod. Tacheometry allows surveyors to measure both horizontal and vertical distances accurately and efficiently. In traversing, tacheometry helps establish control points and measure angles and distances between them. The steps involved in using tacheometry for traversing include setting up the instrument, taking observations, calculating angles and distances, and plotting the traverse. In contouring, tacheometry is used to determine the elevation of points on the ground and create contour lines. The steps involved in using tacheometry for contouring include setting up the instrument, taking observations, calculating elevations and contours, and plotting the contours. Tacheometry has various real-world applications, such as road construction, building construction, land surveying, and topographic mapping. It offers advantages like speed, efficiency, suitability for rough terrains, and accuracy. However, it also has limitations, such as the need for skilled personnel and susceptibility to atmospheric errors.

Analogy

Imagine you are a detective trying to solve a crime. You need to establish the locations of various clues and measure the angles and distances between them. Tacheometry is like having a special detective tool that combines a magnifying glass and a measuring tape. With this tool, you can quickly and accurately measure the angles and distances between the clues, helping you solve the mystery more efficiently.