Test: Fundamental Concepts, Accuracy & Errors - 1 - Civil Engineering (CE) MCQ

1. Cadastral Survey: To establish a boundary of properties for legal use.
2. City Survey: Survey of city
3. Topographical Survey: Surveys which are carried out to depict mountains, rivers, water bodies, wooded areas and other cultural details.
4. Guide Map Survey: For showing relief by contours and spot heights.

Error of area is given by,

Cumulative Errors/Systematic errors:  

(i) The errors that occur in the same direction and which finally tend to accumulate are said to be Cumulative errors.

(ii) They are cumulative in nature. Examples of systematic errors are Collimation in a level, Expansion of steel tape, etc.

(iii) They are proportional to the length of the line.

Working from whole to part prevent the accumulation of cumulative errors due to multiple check points and controlled points already set up from which a part can be plotted accurately without depending on the previous plotted point. 

Cadastral Survey: to establish a boundary of properties for legal use
Topographical Survey: Surveys which are carried out to depict mountains, rivers, water bodies, wooded areas and other cultural details 
Geodetic Survey: Considering earth’s curvature. Usually used when area to be surveyed is greater than 260 sq.km
Cross-Sectioning and Profile Levelling- Collecting sufficient data in connection with sewage disposal and water supply works
City Survey: survey of city
Guide Map Survey: For showing relief by contours and spot heights. 

Systematic or cumulative errors which occurs from well understood causes can be reduced by adopting suitable methods. It follows some definite mathematical or physical iaw and a correction can be-determined and applied.
Accidental errors are those which remain after mistakes and systematic errors have been eliminated and are caused by a combination of reasons beyond the ability of the observer to control. Personal errors arise from the limitations of the human senses such as sight, touch and hearing. Both accidental and personal error represent the limit of precision in the determination of a value. They obey the law of probability and therefore theory of errors and adjustments applies to them.

Standard error of area is given by,

The actual shape of the earth is an oblate spheroid, it is an ellipsoid of revolution, flattened at the poles and bulging at the equator. The-length of the polar axis is about 12, 113.168 km and that of equatorial axis is about 12, 756.602 km. Thus polar axis is shorter than the equatorial axis by about 43.434 km.

Representative Fraction = 1/2500
Scale 1 cm equal to x metre  1cm/(x metre) = 1/100x = 1/2500
Therefore, x = 25 m