Introduction to Survey

ENGINEERING SURVEY

Surveying is the science, art and technology of determine the relative positions of points above, on or beneath the Earth's surface so as to construct a map, plan or description.

TYPES OF SURVEY :

There are many types of survey but we discuss some of them. 

1. Plane & Geodatic Survey :

Ordinary field and topographical surveying in which the Curvature of Earth's surface is disregarded is called Plane Survey. It is performed when the area is smaller than 250sq.km. 

A survey of a large land area in which corrections are made for the Curvature of Earth's surface is called Geodatic survey. 

Why Geodatic Survey is important?

Earth's surface is not flat, it is sphere. So all the calculations which were made by considering the Earth's surface flat are incorrect. So a new type of survey came into play which made calculations on the basis of geodatic condition of Earth's surface. 

2. Topographic Survey :

Topographic survey is used to determine locations of natural and artificial features, geographical properties and elevations used in map making. 

3. Construction Survey :

Construction survey provides line, grade  control elevations, horizontal positions, dimensions and configurations for construction operations.

4. Control Survey :

Control survey establish a network of horizontal and vertical monuments that serve as reference framework for initiating other surveys. 

5. As-built Survey :

As-built survey documents the precise final locations and layouts of Engineering works and record any design changes that may have been incorporated into the construction.

6. Mine Survey :

Mine survey is performed above and below the Earth's surface to guide tunelling, underpass and other operations associated with mining.

7. Route Survey : 

Survey that range over a narrow but long strip of land like highways, transmission lines, underline piping and routes is called Route survey. 

8. Land, Cadastral, Property & Boundary Survey :

It involves in determining locations or in laying out new property boundaries, lines and corners of a particular piece of land. 

Accuracy & Precision :

Accuracy is the relationship between the value of Measurement and the true value of the dimension being measured. 

Precision defines refinement of measuring process and ability to repeat the same measurement with consistently low variations in measurements. 

Error & It's Types :

Error is defined as "the difference between actual and measured value". 

• Errors whose magnitude and algebraic sign can be determined are called Systematic Error. 
• Errors which are due to the improper handling and functioning of instruments by human. 

Mistake :

Mistakes are the blunders which are made by surveyors. Mistakes do not follow any Mathematical rule.