What is Plane Surveying? Types of Plane Surveying

What is Plane Surveying

Plane surveying is a branch of surveying and map making that deals with the measurement of an object from air. It includes the use of remote sensing, satellites, photogrammetry, and radar among other tools.

The plane surveyor can be someone who uses these tools to create maps for a particular project or it may be an independent contractor.

Plane surveying is a typical method of determining land composition and topography that entails treating a specific area of land as if it were a flat plane. The ground being appraised is regarded as a level plane in plane surveying.

Surveyors employ a number of equipment to position points on that plane, which is referred to as the plane table.

Plane surveyors can also help formulate land development plans as well as strategic planning for organizations such as governments or businesses in order to maximize their goal.

Plane Surveying Features

The features of Plane Surveying are:

1. It only takes up a little portion of the earth’s surface. – Plane surveying generally refers to a type of survey that is performed in a small section of land.
2. National survey departments are often in charge of conducting this Survey- though there are also private surveying companies that conduct plane surveys.
3. Spherical trigonometry is employed. Surface lines are assumed to be curve lines, while triangles are assumed to be spherical triangles. – Since the plane being measured is not flat, spherical trigonometry is necessary to measure the curved shape of the plane.
4. The geodetic survey has a high level of accuracy. – When plane surveying, the surveyor must use a combination of trigonometry and basic geometry to get an accurate measurement of the land being surveyed.  It requires an extremely accurate measurement of the curved shape of the plane.
5. It is conducted when the area is smaller than 250 km2.- Plane surveying is a type of survey that is performed in a small section of land.

Types of Plane Surveying

There are various types of Plane Surveying as seen below.

Plane table Surveying

As the name indicates plane table surveying uses a plane table to survey land. With the help of plane table surveying, it is possible to get an accurate measurement of land that is smaller than 250 km2.

 Compass Surveying

In this type of survey, a compass is used to give an indication of the direction of a curve in the plane.

Chain Surveying

In chain surveying, a number of surveying points are used to find the arc length of the curve. It is usually used when the surveyor wants a starting point for future measurements. The number of points in chain surveying is usually equal to one-fourth the length of the curve being measured.

Theodolite Surveying

Theodolite surveying is a type of plane surveying that uses a theodolite to measure the curved shape of the plane. Theodolites have an optical system that allows the user to take extremely precise measurements and angles when taking measurements.

Tacheometry

Tacheometry is a type of plane surveying that uses tacheometers to find the length of curves on a flat surface and portions of an elevation using trigonometric additions.

Levelling

Levelling is a type of plane surveying that uses an instrument called a leveling instrument to remove the effects of the curvature of the earth from surveys.

Instruments used in Plane Surveying

There are two types of instruments used in plane surveying-

• Instruments that use magnetic fields: these include theodolites and levels.
• Instruments that use light: these include tacheometers, planimeters, and perches. A perch is an instrument that uses light to create a curve on a flat surface. It is usually used with a plane table.

The main instruments include:

Theodolite

A theodolite is an instrument that is used to measure angles and heights. It can measure angles up to 90 degrees and can be used to locate points in horizontal planes.

It is usually used with a compass to measure the curvature of a plane which is then transferred in trigonometric calculations, and then converted into a distance value. Theodolites can also be adjusted by using methods called leveling.

Leveling Instruments

In-plane surveying, the level is considered the most important instrument. It is used to remove the effects of the curvature of the earth in a survey or measurement. It works by using a set angle and a target angle to provide true horizontal planes.

Tacheometer

A tacheometer is an instrument that measures height and length on flat surfaces using trigonometric additions.

Surveying Tape

A surveying tape is used to measure distances between two points when conducting plane surveying.

Plane Surveying Procedures

Before planning Plane Surveying these steps are taken.

1. Calculate the area of study-It is important that the surveyor knows how much land that he or she will be surveying. A plane surveyor must also know about the specific project that he or she wants to perform i.e., if he or she wants to draw a map and what kinds of measurements are required for it.
2. Preparation of equipment-Before a plane surveyor sets up for his or her project, he or she must prepare all the necessary equipment. This may include setting up the plane table, leveling instruments and maps/charts of previous surveys that are required to be used as baselines.
3. Location of instrument stations-The surveyor must also locate instrument stations on the map so that he or she can establish a starting point for future measurements.
4.  Measurements from the baseline-The surveyor must measure lengths and angles from the baseline of a previous survey. This will provide an initial starting point for the plane survey.

5. Locating future stations-This is where the plane surveying process starts. The surveyor must now start measuring angles and distances from previously established stations.
6. Transferring data onto a map-Once all measurements are taken, they are transferred onto a flat map so that it can be recorded for future reference purposes.
7. Calculation of horizontal distance-The surveyor must now make sure to transfer the measurements in a proper manner so that each measurement is taken into account. This can be done by doing the measurement from an instrument to a station and then from the same instrument to another station.

After Plane Surveying the following steps are then followed.

1.Establishing an error value of all instruments-At the end of plane surveying, the surveyor must measure distances using a number of different instruments.  He or she must record any differences between the different instruments and create a line of data called “Standard Deviation”. This can be used to find out the maximum error value of each instrument.

2. Establishing an error value for measurements taken-The surveyor must take multiple measurements using the same instrument and record any differences in measurement that may have occurred. He or she must then calculate these differences to find the average error value, which is called standard deviation.

3. Determining a value for grade-Grade is the number of map or drawing sheets that are required to represent one mile of actual distance. Determining this value is done by dividing the length of the survey in inches by 6000 (number of inches in a mile).

4. Finding the scale factor-A scale factor is used to find the ratio of the size of an object on a map to its actual size on land. It is calculated by dividing 1/scale by 2.

5. Calculating the scale factor-Once the surveyor has established an average error value for each instrument and for the measurements taken in a plane survey, he or she must calculate the scale factor.

This is done by measuring distances using three or more different instruments that have known error values. He or she must then divide the measurement taken using each instrument by the mean of all the measurements taken to find a common ratio.

Horizontal Plane Surveying

The following are some of the types of horizontal plane surveying: –

1. Lamb-s method
2. Bentley method
3. The Miller Method (AKA “Leveling” and “Transverse”)
4. Calculation of grade with a tape measure
5. The Holtz Method (AKA “Strip-Pulse”)
6. Datum system (AKA “geodetic survey”)

These types are explained below.

1. Lamb-s method is used to find the error value of a compass when used with a base line. It is done by taking measurements from two known stations. It uses trigonometry to calculate the error value of the compass.
2. Bentley s method is used to find the error value of an instrument when measuring heights using a base line and an angle reading. It uses trigonometry to calculate the error value of the instrument due to curvature of earth and variation in levels at different stations
3. Miller method is used to find the error value of an instrument when measuring horizontal distances. It uses trigonometry to determine variations in vertical angles.
4. Holtz method is used to determine the error value of a compass when measuring horizontal distances with a base line. It uses trigonometry to determine the value of the compass when measuring from a starting point to multiple stations
5. Datum system is used for geodetic surveying, which involves methods for calculating horizontal and vertical values for map making
6. Calculation of grade with a tape measure is used to find the error value of a compass. This method is used by taking measurements from two stations and calculating the difference in measurement.

Vertical Plane Surveying

Vertical plane surveying is the process of measuring angles, heights and obstructions from a horizontal plane. It generally includes measuring altitudes, least vertical distances (LVD), and levels.

Methods Used

The methods used to conduct Vertical Plane Surveying are:

1. Pitman method- This is the most common technique used for vertical plane surveying. It involves erecting a series of triangles along a transect line, whose angles are measured and then plotted onto a surveyor’s map.
2. Bentley method-This is a vertical plane surveyor s tool that measures angles from two known points on the survey line. Each measurement is referenced to the two sides of an angle triangle and compared with nearby measurements to determine error values.
3. Miller method-This is another method used for vertical plane surveying. It involves measuring the distance between two objects and making an angle measurement with a known instrument. This measured distance is then compared with the difference in measurement from the same instrument placed close to the object.
4. Calculation of least vertical distances (LVD)-This is a way of calculating accurate angles when surveying by using LVDs (Least vertical distances). Altitude measurements are usually made from the surveyor’s eye or a telescopic sight.
5. Calculation of levels-This is a way of determining height above land level for map making or for building construction purposes. It is done by measuring the elevation of the ground with a leveling instrument such as an altimeter.

 Information collected when doing a plane survey.

The data collected when conducting Plane Survey are:

1. Datum. (Fictional or measured)
2. The altitude of surveying point or elevation of eye.
3. Least vertical distance (LVD) between two points on survey line.
4. Height of obstructions above surface level.
5. Levels taken at each station to determine the height above surface level of obstructions.
6. Approximate length of the survey line.
7. Approximate width of the survey line.
8. Depth to the bottom of the surface-the distance below the level of an object is obtained by measuring this distance with a ruler.
9. The angle taken between a baseline and any of the other baselines on a vertical or horizontal plane that are a known distance from it (these are called reference lines).

Uses of Plane Surveying

Below are the major uses of Plane Surveying.

1. Map Making-Plane Surveying is usually used to make maps that are used for legal purposes. Surveyors can use many techniques to determine the correct and most accurate representation of the area being surveyed.
2. Building Construction-Plane Surveying is used to determine land boundaries and distances, which are necessary when planning the layout of building structures.
3. Forest Management-Plane surveying is used to monitor clearings or clear-cutting activity in forests.
4. Railway Survey-Plane surveying is used for rail lines and stations.
5. Surveying for road planning and building-Plane surveying is used to help plan roads and buildings.
6. Surveying for construction purposes-In particular, plane surveying is used to determine height from construction sites, heights of structures and areas beneath structures.
7. Airports-Plane surveying can be used to aid analysis of airport plans.
8. Other-Plane surveying is also used to determine the location of underground structures, drainage systems or foundations for building structures, searches for hot spots in volcanic activity and exploration for oil and gas deposits.

FAQs

What is the difference between geodetic and plane surveys?

Plane surveying use standard equipment such as chain, measuring tape, theodolite, and so on. Geodetic surveying use more precise tools and cutting-edge technologies such as GPS.

What is plane survey in civil engineering?

Plane surveying is a sort of surveying in which the earth’s surface is thought to be flat and the curvature of the earth is ignored. A straight line connects any two locations, and polygonal angles are plane angles.

What is the purpose of plane surveying?

Plane surveying is a typical method of determining land composition and topography that entails treating a specific area of land as if it were a flat plane. Because the Earth is not flat, this type of land surveying works best for limited sections of land.

What is the basic assumption for plane surveying?

There are no vertical distances or directions. The plumb line’s direction is the same at all sites within the survey’s boundaries. Every angle (horizontal and vertical) is a plane angle. Elevations are given in relation to a datum.

What is a plane table survey?

Plane table surveying is a graphical survey approach in which field measurements and plotting are done concurrently. It is simpler and less expensive than the Theodolite survey, however it is best suited for small-scale surveys.

What is a plane table surveyor’s rule?

A theodolite, used in the plane table survey, can show only relative differences in height. A plane table surveyor’s rule is an angle measuring device that enables the measurement of precise angles and allows plumb lines to be set accurately and reliably on curved surfaces.

What is the difference between theodolite and plane table surveys?

A theodolite is a precision instrument used to measure angles in vertical, horizontal and slope surveys. All of these distances are measured using vertical angles or other field measurements.

A plane table surveyor’s rule or rod is an angle measuring device that enables measurement of precise angles on curved surfaces and makes it possible to set plumb and level lines reliably on them.

What is the difference between theodolite measuring and plane table surveying?

Theodolite measuring uses plumb lines to measure heights. Plane table surveying measures vertical and horizontal distances with a plane table, which is a more accurate tool for field survey work.

Theodolite measuring is an international standard for field surveying. Plane table survey is a name used by some groups of surveyors to distinguish their own style from that of theodolite measuring techniques used by others.

What are the types of plane surveying?

Chain surveying, plane table surveying, compass surveying, theodolite surveying, and levelling are all examples of plane surveying.

What is plane surveying in geography?

Ordinary field and topographic surveying in which the curvature of the Earth is ignored and all measurements are taken or reduced parallel to a plane representing the Earth’s surface.

What is the difference between plane surveys in architecture?

Plane surveying uses something similar to anodolite, which measures heights with a tripod, has an optical arm, and usually needs leveling or plumb lines attached separately to each piece of equipment.

What is an angle in plane surveying?

Any angle made by a plane, line or point. A small angle is any that does not exceed 90 degrees.

An angle of zero degrees is a right angle, and an angle of 90 degrees is a straight line.

Angles are measured in either degrees (°), minutes (‘) or seconds (‘).

What is the difference between vertical aerial photographs and plane survey?

A vertical aerial photograph, also called a topographic photograph, shows an oblique view of a particular place, typically taken from an airplane.

A plane survey is a relatively small mapping project that is taken with field equipment such as chain measures and plumb poles.