principle of compass surveying

In such an area, the method of traversing is adopted. A compass surveying is performed by means of a magnetic compass which helps to determine the angles and the direction of the survey lines.

This direction is known as magnetic meridian. How to rectify the old cement pipeline leakage problem? Reading is taken through prism provided at the eye slit.

Therefore, this can be used for surveying the land area with undulations which is crowded and large. The horizontal angle is generally measured using a pair of sights located on north – south axis of the compass. The theory behind the magnetic compass and its types are briefly explained.

The bearing of a line is its directions relative to a given meridian.

Traverse, a series of connected lines is measures by a prismatic compass. Become VIP Member. B.B – F.B   =    180       then both stations free from local attraction.

Imperfect sighting of the ranging rods and inaccurate leveling also causes error. A series of connecting lines is prepared using compass and measuring distances using chain. The Local attraction can be  detected by observation of fore bearing and back bearing of each line and finding the difference. (ii)The eye vane consists of a small metal vane with slit. The line of sight is defined by the object vane and the eye vane.

Traversing is the method of locating a series of survey line in the form of a network by placing survey stations one after another. Compass surveying is mainly employed in areas that is free from local attraction. If the surveying area is large, chain surveying is not adopted for surveying rather compass surveying is employed.

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Advantages of Compass surveying. What is Whole Bearing System (WBS) and Quadrantal Bearing System (QBS) in Surveying?

In a compass (prismatic) which uses Whole Circle Bearing (0⁰ to 360⁰) system the included angle is given by, Included angle = F.B of next line — B.B of previous line at same station. Centering involves to align the compass is such a way the Centre is placed vertically over the station point.

Join the crew to get best of the Civil Engineering. However, Most of the land surveying is conducted by compass surveying by the civil engineers and surveyors which helps the foresters, geologists etc.Initially, the theodolites where equipped with a compass which made the same heavy. The magnetic bearings of a line can be determined by a magnetic compass. 2. It has nothing to do with the surveyor and to minimize them, some corrections in calculations applied. For example- 5° 30′, 16° 00′, 35° 30′, The essential parts of the prismatic compass are listed below.

If the bearing of a line AB is measured from A towards B , it is known as forward bearing or Fore Bearing. Traverse, a series of connected lines is measures by a prismatic compass. Login to The Constructor to ask questions, answer people’s questions, write articles & connect with other people. Definition – The commonly used instrument for compass surveying is Compass. This needle swings over a bass circle which is divided into 360 degrees. when there is a time limit for surveying, compass surveying is usually adopted, They have fewer settings to fix it on a station. In compass traversing, the compass is used to determine the direction of survey lines of the framework of the traverse for measuring the angles which these lines make with the magnetic meridian.

The magnetic meridian is thus obtained and then starts to take the measurements by sighting to the next station. Compass Surveying • Chain surveying can be used when the area to be surveyed is comparatively small and is fairly flat. Levelling: The instrument must be held such that the graduated disc swings freely and when viewed from the top edge it must appear level. The greatest advantage of this compass is both sighting and reading can be done simultaneously without changing the position.

The process of chaining and offsetting is the same as in chain surveying and running the check lines is not necessary. If the magnetic meridian is to right side(or Eastern Side) of the true meridian than declination is said to be Eastern or positive declination. This measurement is directly done on the surface of the earth. Please enter your email address.

The temporary adjustments for the surveyor’s compass are the same as that of the prismatic compass. Even after different findings in the field of surveying, this method of compass surveying is still used for preliminary measurements in engineering surveying.

Whenever in traversing compass is used for making angular measurements, it is known as compass traversing or compass surveying.

However, this will require the magnetized needle, a line of sight and a graduated circle.

• But when the area is large, undulated and crowded with many details, triangulation (which is the principle of chain survey) is not possible. True meridian: A-Line or plane passing through geographical north pole and geographical south pole Magnetic meridian: When the magnetic needle is suspended freely and balanced properly, unaffected by magnetic substances, it indicates a direction. It consists of a pair of sights which is used to measure the horizontal angle. They are: Surveyor’s compass is an instrument used in surveying to measure horizontal angles. Some other reasons are: They arise mainly due to the carelessness of the surveyor. Concrete Slump Cone Test Procedure | Applications | Types | Uses, Plastering in Construction – Top 4 Cost Effective Technologies, 11 Best Civil Engineering Telegram Channel [ UPDATED ], Highest Paying Countries for Civil Engineer, Bricks Classification According To Indian Standard, 8 Important Rainwater Harvesting Components and their Uses, Rain Water Harvesting- How, What and Why ?? from the south ( 0 degrees) to West (90 degrees) and North (180 degrees) and East (270 degrees). If the plot for surveying has numerous obstacles and undulations which prevents chaining. Copyright © All rights reserved | Theme by, Track Alignment in Railways | Requirements and factors | Rack Railways |, Surveying in Railway | Survey for Track Alignment | Step by Step Details |, Interlocking of Signals and Points | Methods and Devices used |, Highest Paying Countries for Civil Engineers, Construction steps for laying of cement concrete Pavement slab. If the magnetic needle is not perfectly straight or if it is sluggish, readings may not be accurate. This is merely dependent on the type of compass employed for the measurement. It is the horizontal angle between the true meridian and the magnetic meridian shown by needle at the time of observation.

Magnetic Compass Used in Surveying -Principles & Types.

No observation errors occur. Read More at https://www.researchgate.net/publication/277611855_Compass_measurement_-_still_a_suitable_surveying_method_in_specific_conditions. The main two types of magnetic compass employed are a prismatic compass and a surveyor compass.

The ring is graduated and is read by reflecting prism. It is done with the help of tripod stand and is checked by dropping a small pebble below the Centre of compass. If the plane of sight not being vertical, it also causes error in sighting and reading. The principle of compass surveying is traversing. [PDF], Calculate Quantities of Materials for Concrete -Cement, Sand, Aggregates, Methods of Rainwater Harvesting [PDF]: Components, Transport, and Storage. . It contains a prism which is used for accurate measurement of readings. This method does not requires the need to create triangles.

A compass is small instrument which consists essentially of magnetic needle, a graduated circle and a line of sight.

Quadrantal Bearings – In this system, the bearing of the line is measured eastward or westward from North or South whichever is near. The main principle of compass surveying is traversing. The greatest advantage of this compass is both sighting and reading can be done simultaneously without changing the position.

The main principle of compass surveying is traversing. There are two forms of compass as under -: Prismatic compass is a portable magnetic compass which can be either used as a hand instrument or can be fitted on a tripod. called sources of local attraction. Diametrically opposite to the prism is the object vane hinged to the box side carrying a horse hair with which the object in the field is bisected.

MEASUREMENT OF INCLUDED ANGLE Surveying is the most important branch of civil engineering before and after all the civil engineering works such as designing and construction of roads, buildings, bridges, irrigation and water supply systems etc. Compass surveying is the branch of surveying in which the position of an object is located using angular measurements determined by a compass and linear measurements using a chain or tape. What are the Methods of Interpolation of Contours. The two compass are almost same except few differences so far as their construction is concerned.

Compass traverse may be closed or open. Quantity of Cement and Sand Calculation in Mortar, Types of Foundation for Buildings and their Uses [PDF], Tips to Avoid Reinforcement and Embedment Congestion in Concrete Members, Thumb Rules and Specifications for Design of Reinforced Concrete Beam. Compass surveying Prismatic Compass Compass traversing Important Definition. Country The compass is initially held over the starting station of the survey line and the adjustments are provided. 3.

VIP members get additional benefits. Afterwards turn compass-box until the ranging rod at the station is bisected by horse-hair of objective vane. In this method, the position of different points are plotted on a plan with reference to two lines yy 1 (y-axis) and xx 1 (x-axis) which are respectively parallel and perpendicular to the meridian (Fig. It consists of a circular brass box housing a magnetic needle. The whole housing is then supported by means of a tripod or a suitable stand. It may be due to electric wired , steel structures, railroads, underground iron pipes, etc. In practice compass is generally employed to run a traverse. The theory behind the magnetic compass and its types are briefly explained. It can be held in hand or in a tripod stand for carrying out the measurement. It is easily subjected to various errors such as errors adjoining to magnetic meridian, local attraction etc. (ii)The eye vane consist of metal vane with fine slit. It contains a prism which is used for accurate measurement of readings.

As the name suggests they are arise due to the wrong adjustments of the instruments. A meridian is any direction such as True Meridian and Magnetic Meridian and Arbitrary Meridian. b) Compass Surveying. Compass surveying is used in following circumstances: Compass surveying can be defined as the method of surveying in which the directions of the survey lines is determined by means of a compass and also by using tape or a chain. Explained, Brick Size – Advanced Guide for Civil Engineers and Everyone, The Complete Vastu Shastra : Vastu For House , Home (Tips With images), Bricks – A to Z Information Construction Material. Principle of Compass Surveying . The magnetic meridian is the basis on which the magnetic compass measures the directions. Principle of Magnetic […] But new theodolite does not have a compass in it. 3.

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