Survey Method 04- Methods of leveling

       Three pisicale method are used for determined deference in elevations. Normally barometric leveling, trinometric leveling, and sprit leveling.

1.Barometric leveling

Barometric leveling mark use of the pinerminon that deference in elevation between  2 points is proportional to the difference in atmostiric pressures at the point. A barrow meter there for heavy used and the readings observed at difference points world yield a measure of the relative elevations of those points at a given points. The atmospiaric pressures duos not reaming constant in the course of the even in the course of in hours of the even in the course of hours. There for relatively inaccurate an is little used in surveying work except on reconnaissance for expio rotator surveys.

2.Trigonometric leveling (indirect leveling)

This I s the cross of leveling In which the elevations of points are computed from the vertical angles and horizontal distance measure in the field just as the length of any side in any triangle can be computed from proper trigonometric relations in the  modified from called stadia leveling. Commonly using in mapping broth of the difference of elevations and the horizontal distance between the points are directly computed from the measure vertical angle and staff readings.

3.Sprit leveling(direct leveling )

It is that branch of leveling in witch the vertical distances witch respect to a horizontal line(perpendicular to the directions of gravity). May be used to determined the relative deference in elevations 2 between adjacent points. a horizontal plane of site tangent to level surface at  any point is reading establish by means of a sprit level and a sighting devise(telescope) are combined and vertical distance are measure by observing on graduated rods rise on the point. The method is also known as direly leveling. It is the most precise method of ditumiding elevations and the one most commonly used by engineers.

Calculations.

Methords of baking observations

1.rise staumented

eel. Of point A  = 100.00m RL

rile turn A>B     = 0.87m

eel of point B    = 100.00+0.87

                            = 100.87 m

2. Height of instrument method (line of collimation)

Elevations of point A                = 100.00m RL

Elevations of collimation line = 100.00+2.65(BS)

                                                    = 102.65m RL

Elevation of point B                  =  elevation of line (FS) 1.78 collimation

                                                    = 102.65-1.78                           

                                                    = 100.87m RL                            

BS	IS	FS	Fall	Rise	RL	Distance	Remark
2.65					100.00		Point A
0.52	1.78			0.87	100.87		Point B

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Survey Method 03-Leveling

Leveling is a branch of surveying. The object of which:
I. To find the elevations of give points with respect to a given or assumed datum
II. To establish to point at a given elevations or at difference elevations  with respect to a given or assume datum

The first operation is required to enable the works to be destined wild the second operation is required in the setting out of all kinds of engineering works. Leveling deals with measurement in vertical plumes.

Level surface 

A leveling surface is define as a curved surface which at each point is perpendicular to a directions of gravity at the point the surface of a steel water is a truly level surface. any surface pararal to the mean spheroidal of the earth is there for a level surface.

Level line 

A level line is a line laying in a leveling surface. it is there for normal to the plumb line at all points.
Horizontal plane - Horizontal plane true a point is a plane tangential to the level surface at that point. It is there for perpendicular to the plumb line through the point.
Horizontal line
It is strength line tangential to the level line at a point. It is also perpendicular to the plumb line through the point

Vertical line 

It is a line normal to the level line at the point it is commonly considered to be the line deference by plumb line.

Datum 

Datum is any surface to witch elevations are reflect the mean sea level affords a convention datum world over, and elevations are commonly given as so much oblive or billow sea level. It is often more convenient, however to assume some other datum specially if only the relative elevations of points are required.

Elevations

The elevations of a point on or near the surface on a earth is it’s vertical distance above or below and arbitrarily assume level surface or datum. The deference in elevations between 2 points is a vertical distance between the 2 level surface in which the 2 points lie.

Vertical angle 

Is an angle between to intersection lines in a vertical plane. Generally on of this line is horizontal. Mean sea level M.S.L.  is a coverage height of the sea for all stagers on the tides. At any perpendicular place it is derived by averaging the hourly time height over a long period of 19 years

Bench mark 

Bench mark is a relative permanent point of reference hours elevations with respect to some assume datum is known. It is used ether as a starting points for leveling for as a point upon which to close as check.

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SURVEY METHODS 02

To drop a perpendicular to a chain line from a point out faid  it

1st  method

Select any point E on the line with C as center and CE as various show and arg to out the chain line if F by sect CD will be perpendicular to AB

2nd method

Select any point D on the chain line. Join DC and by select it at E . with E as center and DE  or EC as readies draw and arg to cut the chain line in F. FC will be perpendicular.

3rd method

Select any point E on the chain line witch a center and as radius draw and arg to cut the chain line in F measure FD and FE obtain the point C by macking FC=〖FD〗^2/2FE joint C and D. CD will be perpendicular the chain line.

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SURVEY METHODS 01

To erect a perpendicular to a chain line from a point on it 

The method of establishing perpendiculars with the tape is base on familiar geometric construction. The flowing is same of the methods most commonly used.

3.4.5. method

Establish at point A at a distance of 3m from C. put zero end end of the tape (10m long) at A end the 10m end at C. the 5m and 6m mark brought together to from a loop of 1m. the tape is now stretched tight by fastening  the end A and C. the point A is thus establish the angle BCA will be 900    one person can be set out angle by this method.

2nd method

Select E and F Equidistant from C hold the zero end on the tape at E and 10 meter            end at F. pickup 5m mark, stretch the tight and establish D. joint DC .

3rd method

Select any point F outside the chain line preferably at 5m distance from C. hold 5m mark at F 20m mark at C Witch as center draw and arg to cut the line at E. join EF and produce in to D such that EF = FD = 5m. next dust point D will lie at the 10m mark of the tape head along EF with end zero at E join DC. 

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