Chain Survey

1. It involves taking linear measurement of angular measurements.
2. It is suitable for small area e.g. schools, market etc.
3. It is suitable in flat and open areas e.g. are with no forest or no high mountains

Chain for Surveying

Material: The chain is typically made of steel, ensuring durability and strength for precise measurements.

Length: The chain is usually between 20 meters and 30 meters long, depending on the type of survey and the requirements of the measurement.

Structure: The chain is divided into links, which are small sections. Each link typically measures about 20 cm in length, and the chain can have multiple tallies (or sections marked to facilitate measurement).

Purpose:

1. The primary use of the chain is to measure long distances accurately on the ground, particularly in plane surveying where distances on flat land need to be measured.
2. Chain Surveying is used in boundary marking, land measurements, and other surveying tasks where long, straight distances are to be recorded.

Usage:

1. The chain is laid out on the ground between two points.
2. The surveyor counts the number of links or tallies to calculate the total distance between those points.

Advantages:

1. It provides accurate measurements over relatively flat terrain.
2. It is a simple, reliable tool for land surveys, particularly useful in rural or undeveloped areas.

Tape Measure for Surveying

1. Material: A tape measure is typically made of plastic or steel, offering flexibility and durability. Plastic is commonly used for lighter tasks, while steel provides strength and is ideal for more heavy-duty surveying work.
2. Length: The most common lengths for tape measures used in surveying are 10 meters, 20 meters, and 30 meters. These are suitable for measuring short distances compared to chains, which are used for longer distances.
3. Markings: The tape is usually marked in meters, feet, or centimeters, allowing for precise measurements depending on the surveyor's preference or the requirement of the task.

Purpose:

• The tape measure is primarily used for measuring short distances, such as measuring specific sections of land, boundaries, or small features that require high precision. For example, a 10-meter tape would be commonly used in measuring shorter stretches of land or in smaller construction projects.

Usage:

1. The tape measure is unrolled along the ground between two points.
2. The distance is determined by reading the marked values directly off the tape at the point where it is laid out.

Advantages:

1. Precision: Tape measures are easy to use and can be highly accurate, especially for smaller distances.
2. Portability: They are lightweight and easy to carry, making them convenient for measuring distances in confined spaces or areas with obstacles.
3. Flexibility: They can easily adapt to measuring around curves or other irregular features.

Applications:

1. Short distances like room dimensions, sections of land, or smaller construction sites.
2. Can be used for measuring both horizontal and vertical distances if the tape is held straight and taut.

Surveyor's Band

A Surveyor's Band is a specialized tool used for measuring longer distances with greater accuracy in land surveying.

1. Material: It is made of a steel strip, which offers strength, durability, and the ability to resist stretching, ensuring accuracy over long distances.
2. Design: The steel strip is rolled into a metal frame with a winding handle. This design makes it compact, portable, and easy to store when not in use. The handle allows for quick winding and unwinding of the band.
3. Length: Surveyor's bands are typically available in lengths of 30 meters, 50 meters, or 100 meters. These are suitable for measuring longer distances compared to other measuring tools like chains or tape measures.

Purpose:

1. Surveyor's bands are mainly used for measuring longer distances in field surveys, boundary marking, and site layout for larger construction projects or land demarcation.
2. It is ideal for situations where a tape measure or chain might be too short, offering an efficient way to measure expansive areas without needing to move between points frequently.

How It Works:

1. The steel strip is unrolled and stretched between two points.
2. The length is determined by reading the measuring scale marked on the band.
3. The winding handle is used to roll the band back into the metal frame after measurement is complete.

Advantages:

1. Precision: Due to its material and design, the surveyor's band offers high accuracy over long distances.
2. Durability: The steel strip is strong and less prone to wear and tear, even when used outdoors in rough conditions.
3. Efficiency: With a winding handle, it can be quickly packed and set up, saving time on large surveys.
4. Portable: It's relatively compact, allowing surveyors to carry it easily to different locations.

Applications:

1. Boundary Surveys: When marking the edges of large plots of land.
2. Construction Layout: For determining measurements for large construction sites.
3. Land Development: For surveying rural areas or agricultural lands where large distances need to be covered.

Pegs

Pegs are an essential tool in land surveying, primarily used for marking positions, boundaries, or permanent reference points during a survey.

Material:

• Pegs are typically made of wood, which is durable enough for outdoor use but can be easily driven into the ground.

Size:

1. Length: Usually 40 cm to 50 cm long.
2. Width: Typically 4 mm square, ensuring that they are sturdy enough to stay in place without being too bulky.

Purpose:

1. Marking Permanent Stations: Pegs are used to mark permanent reference points on the land, especially during a survey. These points are essential for later verification and for ensuring measurements are consistent across the surveyed area.
2. Boundary Marking: Pegs are often used to indicate property lines or the boundaries of land parcels.
3. Surveying Points: They serve as markers for the start or end of a survey line or feature, providing a fixed, reliable point for future measurements.

How It Works:

1. Placement: The peg is hammered into the ground at a specific point where a measurement or boundary is to be recorded.
2. Visibility: It often features a small flag, paint, or other marker at the top to make it visible to the surveyor and to other workers.
3. Permanent Reference: Pegs are designed to be long-lasting, marking permanent stations that can be referred to for future surveys or construction activities.

Advantages:

1. Stability: Wooden pegs are stable and easy to install in the ground, ensuring that they stay in place for long periods.
2. Visibility: Pegs, especially when marked with paint or flags, are easy to see, even from a distance, making them useful for navigation during the survey.
3. Cost-Effective: They are relatively inexpensive and can be made from locally available materials.

Applications:

1. Boundary Surveys: Used extensively for marking property lines in land surveys, helping to define the extent of land ownership.
2. Construction Projects: Pegs mark out the locations for buildings, roads, and other infrastructure during construction planning.
3. Topographical Surveys: Used for defining fixed points in surveys to plot elevation changes and contours.

Ranging Rods / Ranging Poles

Ranging Rods (or Ranging Poles) are important tools in surveying, commonly used to mark and establish survey lines. Their bright markings make them highly visible, and they are essential for both horizontal and vertical alignment in land surveys.

Material:

• Wood: The rods are typically made from durable wood, which is lightweight yet sturdy enough to endure outdoor conditions during surveys.

Size:

• Length: The typical length of a ranging rod is between 6 to 10 feet (approximately 1.8 to 3 meters).

Markings:

• Ranging rods are marked with bright colors such as red and white or black and white, allowing them to be easily visible from a distance. This makes them especially useful for establishing a visible reference line during a survey.

Purpose:

1. Marking Permanent Stations: Ranging rods are used to mark specific points on a survey line. These points serve as permanent or temporary references to maintain alignment and ensure consistency in measurements.
2. Aligning Survey Lines: They are placed along a survey line to maintain the direction and continuity of the measurements. They serve as visual references for surveyors, ensuring that survey lines are straight or accurately aligned.
3. Marking Intermediate Stations: In large surveys, ranging rods are often used to mark intermediate stations or points between the starting and ending points of the survey.

How It Works:

1. Placement: A ranging rod is placed at a point on the ground, and other rods are placed at regular intervals along the line being surveyed. These rods help the surveyor maintain a straight line of sight across the land being measured.
2. Visibility: The distinctive colors make the rods visible from a distance, allowing the surveyor to adjust the position of other markers based on these visible references.
3. Alignment: For precise measurements, surveyors use the rods to ensure that the alignment is correct before proceeding with the rest of the survey.

Advantages:

1. Visibility: The bright markings make the rods highly visible in different weather conditions and terrains.
2. Accuracy: They help in maintaining the correct alignment of survey lines, ensuring that measurements are taken accurately and consistently.
3. Portability: The lightweight nature of wooden ranging rods makes them easy to carry and position during a survey.

Applications:

1. Boundary Surveys: Used to demarcate boundary lines in land surveying, ensuring that each section of the land is properly surveyed.
2. Construction Planning: During construction site planning, ranging rods are used to mark out the foundation lines and align the building.
3. Geodetic and Topographical Surveys: They are essential for maintaining the precision of geodetic surveys, as well as in topographical surveys where accurate horizontal alignment is needed.

Cross Staff

The Cross Staff is a traditional surveying tool used to establish right angles or 90-degree angles during a survey. It helps in creating offsets from a survey line, ensuring that lines are laid out at precise angles.

Material:

• Wood: The cross staff is usually made from durable wood, providing a sturdy yet lightweight frame for ease of use in the field.

Size:

• The typical length of the cross staff is around 6 feet (approximately 1.8 meters), making it suitable for positioning at a comfortable height for the surveyor to use.

Purpose:

• The primary function of the Cross Staff is to help surveyors determine and mark right angles (90-degree angles) relative to a survey line. It is particularly useful when creating offsets or measuring perpendicular distances from a baseline or survey line.

How It Works:

1. Positioning: The cross staff is held upright, with the surveyor looking through the cross-shaped opening in the staff. This helps in aligning the instrument to mark precise right angles.
2. Alignment: The surveyor moves the cross staff along the survey line to ensure that the angle formed is a true 90-degree angle. The staff is used to create right-angled reference points or offset lines during land surveys.
3. Determining Offsets: By using the cross staff, a surveyor can set a perpendicular line from the main survey line, which is important for measuring and marking land boundaries, corners, or other specific survey features.

Advantages:

1. Accuracy: It ensures the accurate measurement of right angles, which is essential in survey work for creating correct offset lines and boundary measurements.
2. Simplicity: The cross staff is a simple, easy-to-use tool, making it ideal for basic field surveys where only basic angular measurements are required.
3. Portability: Being lightweight and compact, it is easy to carry and maneuver on the field during a survey.

Applications:

1. Boundary Surveys: Used to establish perpendicular lines from a baseline, which is essential for marking boundaries.
2. Property Surveying: Useful for creating offsets when laying out property lines or plots.
3. Road and Infrastructure Projects: Helps in creating perpendicular lines for positioning features like roads, drainage systems, and utilities.

Other Equipment Used in Chain Survey

Besides the chain and cross staff, several other tools are commonly used in chain surveying to ensure accuracy and efficiency. These include:

1. Optical Square: Used to measure right angles, similar to the cross staff, but with optical precision. It helps in laying out exact 90-degree angles.
2. Ruler: A ruler is used for short-distance measurement or fine adjustments when a more precise measurement is needed.
3. Plumb Bob: A plumb bob is used to ensure vertical alignment and to mark the exact location of survey points on the ground.
4. Field Sheet: The field sheet is used for recording measurements, angles, distances, and any relevant observations during the survey. It's an essential tool for documenting the survey work.
5. Pencil: A simple yet necessary tool for marking measurements on the field sheet and making temporary marks on the ground during the survey.

1. It is suitable for surveying flat surface on the Earth's surface, for example a school compound
2. It can be red easily and quickly
3. It is the simplest method of surveying through the old method
4. It is suitable for surveying clear areas
5. It can be easily repaired or rectified in the field
6. It tends not to attract attention.

1. They become longer or shorter due to continuous use
2. It is not suitable for surveying large areas
3. More difficult areas cannot be chain surveyed
4. Errors may be encountered due to the use of many chains and other reasons
5. It is time consuming
6. They are heavy and take too much time to open or fold
7. It is a slow method of surveying
8. It is the oldest method of surveying

In chain surveying, several types of errors can occur that affect the accuracy of measurements. These errors can be categorized into three main types: Cumulative (Systematic) Errors, Compensating (Accidental) Errors, and Gross Errors.

Cumulative (Systematic) Errors

1. Definition: Cumulative errors, also known as systematic errors, are errors that consistently affect the accuracy in the same direction. These errors accumulate as the survey progresses, causing an increasing discrepancy over time if not corrected.
2. Causes:
   • Incorrect tape length: If the tape used for chaining is not of the correct length, it will consistently measure too short or too long, leading to cumulative errors in measurements.
   • Incorrect tension: If the tape is stretched too tightly or not tight enough, the length measured will be incorrect.
   • Temperature changes: The length of the tape can expand or contract with temperature changes, causing systematic errors in measurements.
   • Not keeping the tape straight: If the tape is not laid straight between two points (i.e., if it sags or is bent), this can result in incorrect measurements.
3. Implications: Cumulative errors, if not identified and corrected, can have a significant impact on the overall accuracy of the survey, leading to errors in the final map or boundary markings.

Compensating (Accidental) Errors

1. Definition: Compensating errors, also known as accidental errors, are random errors that tend to cancel each other out. These errors may be positive or negative and do not significantly affect the overall accuracy of the survey, as they are typically small and unpredictable.
2. Causes:
   • Inconsistent tension on the tape: Variations in how tightly or loosely the tape is held can cause accidental errors.
   • Measurement mistakes: Minor errors in reading the tape or miscounting the number of links during chaining can cause slight discrepancies.
3. Implications: Compensating errors do not pose a significant risk to the accuracy of the survey, as their effects tend to cancel out over time. However, they should still be minimized for best results.

Gross Errors

1. Definition: Gross errors are large, often avoidable mistakes that are typically caused by human error or lack of experience. These errors can drastically affect the final results if not caught and corrected.
2. Causes:
   • Inexperience: If the surveyor is inexperienced or careless, they may make significant errors in recording measurements or misinterpret data.
   • Incorrect chaining: Errors in marking stations or using improper techniques can lead to large discrepancies.
   • Incorrect use of equipment: Not using the proper tools or not calibrating instruments properly can cause gross errors.
3. Implications: Gross errors can lead to severe inaccuracies, potentially invalidating the entire survey. These errors need to be carefully checked and corrected, and proper training and techniques should be used to avoid them.

In chain surveying, obstacles can interfere with the measurement process. These obstacles can be categorized into visual obstacles and chain obstacles, and there are also cases where obstacles can affect both.

Types of Obstacles

1. Visual Obstacles:
   • Definition: These are obstacles that prevent the surveyor from seeing the point they are measuring to but do not obstruct the chain itself.
   • Example: A forest or a building that blocks the line of sight between two points.
2. Chain Obstacles:
   • Definition: These are obstacles that obstruct the chain itself but do not block the surveyor's line of sight.
   • Example: A river or a pond that prevents the chain from being laid directly between two points.
3. Neither Visual nor Chain Obstacles:
   • Definition: These obstacles interfere with both ranging and chaining, requiring special techniques to overcome them.
   • Example: A building or large structure that blocks both the line of sight and the chain's path.

How to Overcome Obstacles

Several methods can be used to overcome obstacles in chain surveying:

1. Rectangular Method:
   • How it works: If the chaining reaches a point where an obstacle is encountered (e.g., a river), a perpendicular line (rectangular method) is set up at the obstacle. This line helps to bypass the obstacle and continue chaining to the destination.
   • Steps:
     • Mark points A (starting point) and B (destination).
     • When the obstacle is encountered, set up perpendicular lines at A and B.
     • Measure along the perpendicular lines to avoid the obstacle.
     • Once past the obstacle, re-measure the line to point B using the corrected distances.
2. Triangle Method:
   • How it works: This method involves forming a triangle to bypass an obstacle. The chain surveyor creates two triangles to bridge the gap where chaining cannot continue directly.
   • Steps:
     • Mark points A and B.
     • Identify a point C that allows the chaining to bypass the obstacle.
     • Use the triangle method to calculate the distances to the obstacle and back to point B.
3. Similar Triangle Method:
   • How it works: This technique uses similar triangles to extend the survey beyond the obstacle. The concept of similar triangles allows for the use of proportional relationships to continue measuring accurately.
   • Steps:
     • When the chain reaches an obstacle, create a small triangle on one side of the obstacle.
     • Construct a larger triangle on the other side of the obstacle, ensuring proportionality between the two triangles.
     • By measuring the sides of the smaller triangle, the larger triangle's corresponding sides can be calculated, allowing the surveyor to continue chaining beyond the obstacle.

When an obstacle like a stream or a building obstructs the direct chaining between two points (A and B), the triangle method can be used to bypass the obstacle and continue the chaining process. Here's how the method works step-by-step:

Steps for Constructing Triangles to Overcome Obstacles

1. Mark Points A and B:
   • Begin by marking the starting point A and the destination point B. The goal is to measure the distance between these two points, but an obstacle (e.g., a stream) blocks the direct path.
2. Set Out a Perpendicular Line (AC):
   • From point A, construct a perpendicular line AC that will help navigate around the obstacle.
   • AC should be long enough to bypass the obstacle.
3. Mark the Midpoint (E):
   • Find the midpoint E along line AC. This is a reference point that will assist in aligning the necessary triangles.
4. Set Out a Second Perpendicular Line (CD):
   • From point C, construct another perpendicular line CD. This line should be in such a position that points D, E, and B are collinear (i.e., they lie along the same straight line).
   • CD is set in a way that it allows you to bypass the obstacle and bring the chaining back on track.
5. Congruency of Triangles:
   • The two triangles formed—ACD and ABE—are congruent (meaning they are identical in shape and size). The congruence of these triangles means that the length of CD is equal to the length of AB.
   • Therefore, the distance CD equals the distance AB, which is the required measurement to continue the chaining.
6. Complete the Survey:
   • With CD = AB, you can now continue the chaining process as if there was no obstacle.
   • The chaining can proceed from point B, having bypassed the obstacle, and you can now record the correct distance.

1. It helps in determine distance between various points on the ground
2. It helps to determine heights on the ground
3. It helps to determine angles on the ground
4. It helps in determine areas of plots of land
5. It helps to take ground measurements for construction of various structure E.g roads, buildings e.t.c
6. Leveling survey helps to determine level of sloped ground
7. It helps to determine for sight intermediate and back sight of various points on the ground especial sloped land.
8. Survey is help in taking measurements to some areas where underground structure to be constructed E.g. pipeline, underground canal etc.