What is Surveying ?Surveying is a method of determining accurately, points and lines of direction (bearings) on the earth's surface and preparing from them, maps or plans. Boundaries, areas, elevations, construction lines, and geographical or artificial features are determined by the measurement of horizontal and vertical distances and angles and by computations based on geometry and trigonometry.

What is Surveying?• Surveying can be defined as:

– The art of making measurements of the relative positions of natural and man made features on the earth’s surface and the presentation of this information either graphically or numerically

Bannister, A. Raymond, S., and Baker, R., 1998, Surveying

• The basics of surveying haven’t changed.– Egyptians and Greeks measured using

differential leveling, distance, and angles.

• There are two types of surveying:– Geodetic and Plane Surveying

Types of Surveying

• Geodetic– Accounts for curvature of the earth.– Used mostly for national mapping programs.– Needs to be highly accurate.

• Plane Surveying– Treats the earth’s surface as a flat plane.– The instrument is always leveled according to the

center of the earth (gravity level/plumb bob).– Only appropriate for smaller areas.

(less than 250 km2)

Why might you want to survey?

• It is a handy skill:– You may rent a level & rod if you don’t own one.– May use it to lay out foundations or driveways.– To arrange contours in your fields.

• To understand what professionals are doing.– When you see a surveying crew at work.– When a crew is surveying your land.

SURVEYING EQUIPMENTSSURVEYING EQUIPMENTS

The Gunter's chain The Gunter's chain (known also as the (known also as the surveyor's chain), which surveyor's chain), which is 20 m long and divided is 20 m long and divided into 100 linksinto 100 links

linkslinks

The engineer's The engineer's chain, 30 m chain, 30 m long and also long and also consisting of consisting of 100 links100 links

The tape, The tape, usually of usually of steelsteel

THEODILITETHEODILITE ROD OR ROD OR STAFFSTAFF

FIELD BOOKSFIELD BOOKS

DIGITAL DIGITAL FIELD BOOKFIELD BOOK

Basic principles of plane surveyingBasic principles of plane surveying Consider a simple survey Consider a simple survey situation as shown on the situation as shown on the left. To plot the area left. To plot the area accurately it is essential accurately it is essential to establish a base line to establish a base line first. first. Once a base line is Once a base line is established, the points established, the points can be located relative to can be located relative to the line by taking two the line by taking two measurements with the measurements with the following possible following possible combinations:combinations:

Two distancesTwo distancesTwo anglesTwo anglesOne distance and one angleOne distance and one angleOne distance at 90 , offsetOne distance at 90 , offset

Basic CHAIN Basic CHAIN SURVEY – two SURVEY – two distances. AC and distances. AC and BC are measured. BC are measured. Point C is drawn by Point C is drawn by intersecting Radii intersecting Radii AC and BC.AC and BC.

Basic Basic TRIANGUALTION – TRIANGUALTION – twotwo Angles ABC Angles ABC and BAC are taken. and BAC are taken. Point C is located Point C is located using the using the Intersection of the Intersection of the angles.angles.

Basic TRAVERSE Basic TRAVERSE – distance and – distance and angle. Point C is angle. Point C is located by the located by the measured measured distance of AC distance of AC and the angle and the angle ABC.ABC.

Basic OFFSET – Basic OFFSET – distance at 90 distance at 90 degrees. Point C degrees. Point C is located by the is located by the distance on a distance on a line line perpendicular to perpendicular to base line AC base line AC through C.through C.