AREA & VOLUME CONCEPTS

Kaustubh J. SaneHJD institute of Technical Education & Research, Kera

• Calculating area and volume of simple geometrical shapes• This is an analytical method for computing the area of plot

and converted to graphic method.• The area is divided into suitable geometrical figures like

triangle, square, rectangle. • Area of triangle= √s(s-a)(s-b)(s-c)• Area of triangle= ½*b*h• Area of triangle= ½*a*b*sin Ө, Ө is angle between two

sides of triangle.

• Calculating area of plot with irregular boundary from field notes

• Area of field can be directly calculated from field notes.

• During survey work whole area is divided into some geometrical figures like triangles, rectangles, square, or trapezium.

• Calculating area of plot with irregular boundary • The area may be calculated in following ways– Considering entire area• By dividing the area into triangles• By dividing the area into squares• By drawing parallel lines and converting them to

rectangles

– Middle area+ boundary area

• Triangle area= ½* base* altitude

• Preparing squares of equal area 1cm or 1m

• Area= nos. Of square * unit area

• Area= ∑length of rectangles*constant depth

Linear measurement

• To measure a horizontal distance between two points in surveying work is called as linear measurements.

• Two methods – Direct- computing the actual distance with help of

chain and tape– Indirect- computing is carried out with help of

optical instruments in areas where to reach and measure is difficult to carried out.

• Use of linear measurements– Area calculation of site– Volume calculation of site– Dividing the site in regular shapes with

measurements.• Instruments used for linear measurement• Chain• Tape

• Chain– Metric chain- length of link is 20cmmay be of 20m

or 30m in total length.– Gunter’s chain- 66feet long consist of 100 links

each of 0.66feet. Here 10square chains = 1acre; 10chains = 1 furlong, 8 furlong= 1mile

– Engineer’s chain- 100ft long, 100 links, each link is of 1ft.

– Revenue chain- 33ft long, with 16 links, used for distance measurements in ft and inches

– Steel band chain- more accurate than others, it may be of 20m, 30m. And have marking at every 20cm

• Tapes-– Cloth tape- 10, 20, 25 or 30m – Fiber glass tape- flexible non conductive– Metallic tape– Steel tape– Invar tape

• ELEVATION:• Introduction to leveling & contours• Define contour line • Uses of contour map