How to Achieve Perfect Leveling with the Rise and Fall Method

Rise and Fall Method in Leveling     

        Leveling is a fundamental technique used in surveying to determine the height of points by using other known points as references. In this tutorial, we will learn about the Rise and Fall Method, a popular technique used in leveling, and its application in determining reduced levels of the ground.

What is the Rise and Fall Method?

        The Rise and Fall Method is a technique used in leveling to determine the difference in height between two points, independent of the datum. It involves taking measurements of the height of a point from a reference point and then calculating the difference in height between the two points. The method is commonly used in surveying to create longitudinal sections, cross-sections, and contouring.

Commonly Used Terms in Leveling: 

        To understand the Rise and Fall Method, it's essential to know some commonly used terms related to leveling and basic surveying. Here are a few definitions:

•Datum: A reference point or surface used to measure heights or depths.

•Reduced Level: The height of a point relative to the datum.

•Height of Instrument (HI): The height of the level above the datum.

•Backsight (BS): The reading taken on a leveling staff held on a point of the known reduced level.

•Foresight (FS): The reading taken on a leveling staff held on a point of the unknown reduced level.

Rise and Fall Method 

Application of Leveling: 

Leveling finds its application in various assignments, including:

👉 Determining point heights relative to a datum

👉 Measuring height differences between two points independent of datum

👉 Creating longitudinal sections and cross-sections

👉 Contouring

👉 Land Surveying

👉 Topography

👉 Boundary Alignment 

Rise and Fall Method Calculation: 

        The Rise and Fall Method can be calculated in two ways: the Rise and Fall Method and the Height of Collimation Method. In this tutorial, we will focus on the Rise and Fall Method. The following steps are involved in the calculation:

1. Take a backsight (BS) reading on a staff held on a point of the known reduced level.
2. Calculate the height of the instrument (HI) by adding the backsight (BS) reading to the elevation of the instrument.
3. Take an intersite (IS) reading on a staff held on a point of the unknown reduced level.
4. Take a final reading on a staff held on the same point as the foresight (FS) reading to determine any errors.
5. Calculate the reduced level of the point by subtracting the foresight (FS) reading from the height of the instrument (HI).
6. Repeat the process for other points.

Arithmetic Check: 

        After the calculations are done, an arithmetic check can be performed to ensure the accuracy of the measurements. The check involves adding up the backsight (BS) readings and foresight (FS) readings separately and ensuring that they are equal. If the sum of the backsight (BS) readings is equal to the sum of the foresight (FS) readings, then the calculation is correct.

Conclusion: 

        The Rise and Fall Method is a crucial technique in surveying and leveling. It provides an efficient and accurate way to determine the reduced levels of the ground. Understanding the method and its calculations is essential for any surveyor or engineer.

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