1.5.1. Types of survey based on instruments

Earlier, measurements of distances and directions were mainly used to prepare maps of the area, and surveys were classified based upon the instruments used.

In the past, surveys primarily relied on basic instruments to measure distances and directions for creating maps. Different types of instruments dictated the methods employed for surveying, helping to categorize the different surveying techniques.

Think of how a chef uses different tools like knives, blenders, or ovens for different cooking processes. Similarly, surveyors use various instruments according to the measurement needs of the project.

In chain survey, a metallic chain is used to measure the linear distances. The chain traversing is done by dividing the small area to be surveyed into a number of triangles.

A chain survey is a traditional method where physical metallic chains of certain lengths (typically 20 or 30 meters) are utilized to measure distances accurately. These distances are then structured into triangles, helping to form a network of control points that can be easily surveyed.

Imagine measuring a large kitchen countertop by stepping out lengths with a measuring tape. You create smaller sections or rectangles to easily calculate the area, similar to how surveyors create triangles.

Many different varieties of measuring tapes are available, with different materials, lengths and designs.

Measuring tapes come in various materials, typically fiber glass or stainless steel. They are used for measuring lengths, but each type has its strengths; for example, steel tapes are durable but can rust if not maintained. Measurements longer than 30 meters may be problematic due to sag.

Consider using a long ribbon to measure your garden's boundary. If it's too long and heavy, it might hang in the middle, leading to inaccurate measurements, just like a tape measure can sag over long distances.

A level instrument is used to find the difference in elevation between the points.

Levels are crucial for determining elevation differences. They work in conjunction with a graduated rod known as the leveling staff. The process involves linking observed points with known ones to calculate the elevation of unknown points.

Think about leveling a picture frame on your wall. You use a level to see if it’s perfectly horizontal compared to the ground. In surveying, similar principles apply to ensure buildings or roads are level compared to the land.

A theodolite is used to measure horizontal and vertical angles.

Theodolites allow surveyors to measure angles both horizontally and vertically. They are often used in traversing and can help establish control lines and points accurately, which are crucial for larger projects.

Imagine turning your head to look at different objects in a room. A theodolite does the same by measuring angles to understand their positions relative to each other on a larger scale.

A magnetic compass works on the principle that a freely suspended needle points in the magnetic north-south direction.

The magnetic compass provides directional information, helping surveyors determine the orientation of a line relative to magnetic north. It’s often used in tandem with other tools to assist in surveying tasks.

Think of how you use a compass while hiking to find your way through the woods. Surveyors use compasses similarly to align their measurements with the earth's magnetic field.

With the advancement in electronics and digital technology, many modern instruments are now available for data collection and mapping.

Modern surveying equipment like Total Stations, Laser scanners, and GPS have revolutionized the field. These instruments can collect and process data efficiently, allowing for greater accuracy and ease of use, often replacing traditional methods.

Just as smartphones have replaced many devices like cameras and GPS, advanced surveying tools provide functions that were once spread across multiple devices, streamlining the surveying process.

--