UKSSSC- Surveying-II

 INTRODUCTION

All about the basics of surveying is discussed in surveying-I. Therefore, if you miss to read Surveying-I ; Please go to home index and read it carefully. Here I will discuss about the following are- 

♀ Contouring

♀ Theodolite

♀ Techometric Survey

♀ Curves

Please mind it, here I'll focus only that points who is necessary in the prospects of UKSSSC or UKPSC JE.

📝CHAPTER-1: CONTOURING

Contour is an imaginary lines which are passing through the points of equal elevation.

◆ Contour Interval:- The vertical distance between two consecutive contours.

👉 Contours interval always constant for a map or plan.

◆ Horizontal Equivalent:- The horizontal Distance between two consecutive contours.

◆ Selection of contours interval-

● Nature of ground

● Purpose of map

● Types of scale 

● Time

● Funds

Various work              Contour Interval value

1. Building site               0.5m

2. Town planing             1.0m

3. Location survey         2.0m

4. Reservoir                    0.5m

5. Large scale                0.5m

6. Small scale                1m,2m,3m...

◆ Characteristics of contours-

● All points of contour line have same elevation.

● Contour line widely separated- flat ground

● Contour line closely together- Steep ground

● Contour line straight, parallel and equally spread- Plane surface

● Contour line informally placed- uniform slope

● Contour Interval Decrease inward and Increase outward - Depression or pond

● Contour Interval Increase inward and Decrease outward - Hill

👉 Contour lines are not drawn across the water in river or stream. Because water level is not constant.

👉 The contour interval is kept inversely proportional to steepness & configuration of the area.

👉 The place where contour lines meet at right angle called ridge.

📝CHAPTER-2: THEODOLITE SURVEYING

Theodolite surveying is most accurate surveying as compare to compass surveying. Compass can measure only horizontal angle but Theodolite can also vertical angle as well as horizontal angle. The least count of transit theodolite is 20" (20 sec) and the least count of Optical theodolite is 1" (1 sec) in the favour of degree.

◆ Theodolite classification-

I)- Transit Theodolite

II)- Non Transit Theodolite

1- Transit Theodolite-Telescope can be revolved through a complete revolution about its horizontal axis in a vertical plane. Transit theodolite is widely used.

2- Non Transit Theodolite- This is not revolved or rotate about its horizontal axis in the vertical plane. Non Transit Theodolite are following two types are-

♀ Vernier Theodolite- Vernier fitted with main plate.

♀ Micrometer Theodolite- Micrometer fitted with main plate.

👉 The diameter of graduated circle of the lower plate define the size of theodolite. Theodolite are varies height either 8cm to 12cm or 8cm to 25cn.

👉 Use the steel tape for measurements in traverse survey with theodolite.

👉 Least count of vernier is -d/n

◆Traverse survey with theodolite-

● Measurement of angle b/w successive line - Where High Degree Accuracy is required

●Direct measuring of bearing- Where great precision not required.

◆ Angle measurement at various stations are-

♂ Included Angle

♂ Direct Angle

♂ Deflection Angle

👉 For measurement of left deflection angle, telescope is moved in anticlockwise direction. normal telescope is left face position.

👉 Direct observation of bearing method is also known as Fast needle method.

👉 Fast needle method used to measuring the magnetic bearing of traverse.

👉 Exact adjustment of theodolite done by slow motion tangent screw.

◆ Traverse - 

I)-Open Traverse- The algebraic sum of latitude and departure is not zero.

II)-Closed Traverse- The algebraic sum of latitude and departure is equal to zero.

◆ The closing error in bearing is the difference b/w two bearings of the last line as measured at the first and last station of traverse.

♀ correction to 1st bearing = e/N

♀ correction to 2nd bearing =2e/N

♀ correction to last bearing = e

Where e= closing error in bearing

N= Number of side of traverse

Closing Error = √{(ΣL)^2+(ΣD)^2}

Here L= Latitude, D= Departure

Tan¢ = ΣD/ΣL 

👉 ¢ is always in R.B (Reduce Bearing)

👉 In closed traverse deflection-

ΣL.H.Angle - ΣR.H.Angle = 360°

Considered quadrant clockwise direction from N

◆ Balancing of Traverse- The latitude and departure are so adjusted that the algebraic sum of latitude and departure each is equal to zero.

◆ Correction to balance the traverse-

1-Bowditch rule- Correction L or D of any side = Total error in L or D × (Length of that side / perimeter of traverse)

2- Transit Rule- 

● Correction in L = Length of that line × (total error in L/ arithematic sum of all latitude) 

● Correction in D = Length of that line × (total error in D/ arithematic sum of all departure) 

3-Third rule- 

● North correction= 1/2 total error in L × (Northing of that line / sum of northing)

● South correction= 1/2 total error in L × (Southing of that line / sum of southing)

● East correction= 1/2 total error in D × (Easting of that line / sum of easting)

● West correction = 1/2 total error in D × (Weasting of that line / sum of weasting)

👉 Accurate Included angle measured by repetition method.

👉 Under ordinary condition, the precision of a theodolite traverse is effected by systematic linear error.

👉 The latitude passing through the centre of india is Tropic of cancer.

📝CHAPTER-3: TECHOMETRIC SURVEYING

Horizontal and Vertical distance of points are determined by taking angular observation.

◆Techometer- Transit theodolite fitted with a stadia diaphragm.

Note the following 👇

♂ The magnification power of telescope should be 20 to 30 times of diameter.

♂ In order to have Bright Image the aperture of objective should  be 35 to 45 mm

♂ The value of additive constant should be zero (0) when the anallatic lens is fitted telescope. Otherwise additive constant is 10cm to 20cm when internal focusing type telescope is used.

♂ The value of multiplying constant should be 100.

♂ stadia techometry was discovered by James watt in year 1900.

◆About staff used in Techometry-

● small sight - Ordinary levelling staff is used. The least count of staff is 5mm.

● Intermediate sight- Stadia rod used. These are special graduated rods either in piece or folded type. Least count varies 5mm to 10mm.

● long sight- when the length of sight is more than 100m, Target staff is used.

◆ Principles of Techometry-

I)- Fixed Hair method or stadia constant method- 

Lens formula 1/f = 1/f¡ + 1/f¡¡

® Distance b/w the vertical axes of instrument and staff-

D = f/i ×S + (f+d)

Here f/i = multiplying constant (K say)

(f+d) = additive constant (C say)

S = staff reading

Therefore D =K.S+C

II)- Tangential Method-

♂ when both the observed angle are the angle of elevation -

D = S / (tan¢1 -tan¢2)

V = S×tan¢2/ (tan¢1 -tan¢2)

R.L of staff station = R.L of line of sight +V- h

♂ when both the observed angle are the angle of depression -

D = S / (tan¢2 -tan¢1)

V = S×tan¢2/ (tan¢2 -tan¢1)

R.L of staff station = R.L of line of sight -V- h

♂ when one observed angle in elevation and another is depression-

D = S / (tan¢1 + tan¢2)

V = S×tan¢2/ (tan¢1 + tan¢2)

R.L of staff station = R.L of line of sight -V- h

📝CHAPTER-4: CURVES

Curves generally provides to change the direction. Change the direction in horizontal plane called horizontal curve and change the direction in vertical plane called vertical curve.

Classification of curves in survey- there are the following four types of classification available in terms of survey-

I)-  Simple Curves

II)- Compound Curves

III)- Reverse or Serpentine Curves

IV)- Deviation Curves

I)- Simple Curves- A simple curve consists of a single arc of a circle connecting two straights. It has radius of the same magnitude throughout.

II)-Compound Curves- A compound curve consists of two or more simple curves having different radii bending in the same direction and lying on the same side of the common tangent. 

III)- Reverse or Serpentine Curves- A reverse or serpentine curve is made up of two arcs having equal or different radii bending in opposite directions with a common tangent at their junction. Their centres lie of opposite sides of the curve. Reverse curves are used when the straights arc parallel or intersect at a very small angle. They are commonly used in railway sidings and sometimes on railway tracks and roads meant for low speeds. They should be avoided as far as possible on main railway lines and highways where speeds are necessarily high.

IV)- Deviation Curves- A deviation curve is simply a combination of two reverse curves. It is used when it becomes necessary to deviate from a given straight path in order to avoid intervening obstructions such as a bend of river, a building, etc.

◆ Relationship b/w Degree and Radius of curve-

Here discuss about the 30m and 20m chord length. In this handwriting notes you may see the complete solution. 

R = 1719/ D for 30m chord

Here 1° represent 1719m

R = 1146/ D for 20m chord

Here 1° represent 1146m

D stand the degree and D° = 1719C/R,  this is known as Rankine's Tangential Angle.

◆Centrifugal Ratio, C.R = V²/gR

◆Super Elevation-

♀ Road - h = bV²/gR

♀ Railway - h = GV²/gR

Various part of curves-

◆ Intersection angle+deflection angle = 180°

◆  Tangent length BT1 = BT2 = R tan¢/2

◆  Length of chord T1T2 =2Rsin¢/2

◆ Length of curve T1ET2 = R¢° or  πR¢/180°

◆ Apex distance BE = R [sec¢/2-1]