civil engineering LINEAR SURVEYING.pptx

survey levelling

1. RANGING 1

2. The process of establishing intermediate point on a straight line between two end points is known as ranging.” 2 Ranging :

3. Types of Ranging There are two types of ranging: 1. Direct ranging 2. Indirect ranging 3

4. Ranging if the points are inter visible Direct Ranging A P Q R B S 4 Direct ranging is done when the two ends of the survey lines are inter visible. In such cases , ranging can be done by eye or through some optical instrument such as theodolite etc.

5. 2 . Indirect Ranging Ranging when points are not visible 5

6. Types of Measurements in Surveying 1 . Linear measurements 2 . Angular measurements Linear measurements are further classified as follows: i ) Horizontal Distance ii ) Vertical Distance 6

7. i ) Horizontal Distance A horizontal distance is measured in horizontal plane. If a distance is measured along a slope, it is reduced to its horizontal equivalent 7

8. Chaining on Sloping Ground There are two methods for determining horizontal distance on sloping ground . 1 . Direct Method 2 . Indirect Method 8

9. 1. Direct method – distance measurement along sloping ground This method is also known as “Stepping Method”. The horizontal distances are directly measured by the process of stepping . Horizontal distance PQ = S1 + S2 + S3 + S4 + S5 9

10. ii ) Indirect Method of Chain Surveying In this method, the sloping side is measured on the ground and later it is converted into the horizontal equivalent. The following methods are adopted for calculating horizontal distance indirectly: i) By measuring angle of inclination ii)By measuring difference of levels 10

11. i) By measuring angle of inclinational (Slope distance and angle α are measured) A B C α D L h D = L . C os α ii)By measuring difference of levels (Distance along the slope and the difference in elevation between A and B are measured .) 11

12. Principle of linear survey A triangle is a simple figure which can be plotted from the lengths of three sides even if the angles are not known. In chain survey, the area to be surveyed is divided into a framework consisting of triangles . For good results in plotting, equilateral triangles(as nearly as possible) are preferred. 12

13. Survey station and survey line The principle of chain survey is chain triangulation. Survey station: It is a prominent point on the survey line and can be either at beginning or end of chain line It is marked on the ground by driving pegs, if ground is soft. If the surface is hard like roads, survey station can be marked with reference to 2 or 3 permanent objects near the station. 13

14. Survey lines Main survey lines :- Lines joining the main survey stations are called main survey lines. Base line :-The biggest of the main survey line is called base line. Check line :- Check lines or proof lines are run in the field to check the accuracy of the work. A,B,F & C = main survey stations AB = base line DC & EF = Check line A B C D E F 14

15. https:// youtu.be/x8FaSZCPbM8 https:// youtu.be/9gs-mnpla3Y 15 VIDEO LINK

16. Thank you 16