Chain surveying is a type of land surveying that focuses on measuring straight distances in the field without using angles. It’s used for surveying small areas that are mostly flat and not too complicated. In chain surveying, the land is divided into many small triangles. We use chains or tape measures to measure the distances between points, and sometimes, we use trigonometry to figure out how far apart things are. This method is simple and doesn’t cost a lot of money. It gives us quick information about the triangles in the area we’re surveying. In chain surveying, we look at different types of details:

Hard details: These are things like buildings, roads, and walls; basically, anything solid and man-made on the land.

Soft details: This includes vegetation like trees, bushes, and grass, as well as natural features such as rivers and streams.

Overhead details: These are things above ground level, such as power lines and telephone lines that crisscross the area.

Underground details: This category covers things beneath the surface, like water pipes and sewer systems that are hidden from view.

Chain surveying helps us gather information about all these different types of details to understand the layout and features of the land we’re surveying. The requirements for fieldwork are

• Tape 
• Chain
• Arrows 
• Cross staff
• Ranging-Rod

Calculation of Earthwork in Surveying

Earthwork calculation is important in surveying because it helps manage costs during construction processes by balancing the amount of soil cut and filled on a site. For roads, accurate earthwork measurements ensure a level surface and proper banking where needed. In building construction, precise earthwork calculations determine foundation depth and achieve desired levels for floors and formations. This ensures that construction progresses smoothly and meets structural requirements.

What is Earthwork? Earthwork involves reshaping the earth’s surface by moving soil, rocks, or other materials to create the desired landscape or conditions for construction. It’s often called excavation work because it includes digging and moving earth and rocks to prepare a site. Earthwork isn’t just about soil; it also includes handling unformed rocks as part of engineering processes.

Needs for Earthwork Calculation 

Once the surveyor has completed plotting and finalising the plan of a geographic area, the next step is to determine its area. The shape of the plotted area can be irregular, not just simple shapes like rectangles. You also seek assistance from earthwork estimating services for your construction work. 

Calculating these areas and volumes is important for several reasons:

• It assists in building barriers for roads and railways.
• It’s important for designing dam reservoirs to know their capacity.
• It allows for evaluating water loss due to evaporation from a reservoir.
• These calculations ensure that construction projects are planned accurately and efficiently.
• It helps determine how much earth needs to be moved, whether it’s filing or cutting the ground.

Methods for Earthwork Estimating 

There are three different methods popularly used for doing earthwork Calculations for Cutting/Filling Projects. Let’s first understand some basic terms related to earthwork calculations. 

• Cutting: Cutting is when you dig out the earth to shape the land the way you want it.
• Filling: Filling is when you add soil or other material to a site to shape the land the way you want it.
• Earthworks: Earthworks involve moving large amounts of soil or rock to reshape the land according to a planned design. This process includes cutting into existing ground and filling in other areas to achieve the desired shape and levels of the land.

1. Average method

In this method, we find the levels at each grid point. We calculate the difference between the average levels of two sets multiplied by the area to get the result. It’s simple but works only when there’s either cutting or filling. If the surface involves both cutting and filling, the average method can give incorrect results because the cutting and filling cancel each other out when averaged.

2. Block Method (Division of Square Method)

In this method, we calculate the volume of cutting or filling for each block and add them up to find the total volume. It’s simpler than the Section Method and more accurate than the Average Method. However, like the Average Method, it can also have issues when there’s both cutting and filling in the same block, which can lead to some errors. However, overall, this method has a smaller margin of error compared to the average method for the entire area.

Note: In this example, even though there is some cutting happening, the values cancel each other out in the same block, so we don’t see any cutting value reflected.

3. Section Method

In this method, sections are drawn for each line of value. We calculate the area of cutting and filling for each section using methods like trapezoidal or net area calculation. Then, to find the volume, we multiply the average area by the distance between sections. This method is more accurate, but it can be challenging for larger areas because we have to locate where lines representing surfaces intersect.

Calculation of Area

Area is often measured using a tool called a Planimeter. Alternatively, you can calculate the area using mathematical formulas, which are explained below:

1. Mid Ordinate Rule

2. Average Ordinate Rule

3. Simpson’s One-Third Rule

4. Trapezoidal Method (Trapezoidal Formula For Earthwork Calculation)

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Calculation of Volume

When we discuss Earthwork Estimating Calculation, we’re essentially talking about measuring the volume of the earth moved. There are two methods to calculate this volume:

1. Trapezoidal Method

2. Prismoidal Method

Summary

Chain and level surveying were used to calculate earthwork, focusing on measuring distances in flat areas using triangles. Earthwork calculation is important for controlling construction expenses and achieving desired site levels. It explains methods like average, block, and section for calculating volume and covers earthwork techniques such as cutting and filling. Techniques such as trapezoidal and prismoidal methods are highlighted for accurate volume measurement. Understanding these methods ensures effective construction planning and execution.