Surveying (Civil Engineering )

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2023-07-21T22:07:00.001-07:00

Instant Solution App | Vertical Curve Full Stations Elevations, High or Low Point, Diagram Layout | Free to Use

2022-03-23T04:14:00.035-07:00

Hi,
Please input the gradient values in percentage (%), for example g1 (%) = 2, g2 (%) = -3.
Don't include the % sign. The other values can be put as needed, example lenth L (ft) = 1000.
Finally, hit the "Submit" button, and wait for the solution.

Input Fields

Unit of Length (example: ft, m, etc.)

g1 (%) (+ve upwards)

g2 (%) (+ve upwards)

L, curve length

Choose Station with Given values

Chainage ex: 1000

Elevation, ex: 80.0

Full station Spacing interval at which elevations are to be calculated

Python(Programming Language) Code to Solve a Horizontal Curve, Degree, Radius, Length, Long Chords and Tangent Length

2020-09-12T20:04:00.002-07:00

For Civil Engineers, Curves are to be taught in their Surveying course. Once you understand everything on the conceptual level, you can go to the next level by creating programs on software languages such as Python. Python can be easily installed on your computer, and you can run the following codes on that to get the solution. You can run it on Pycharm or IntelliJ etc. Try the code that I am giving below.

So here is the problem.

Given: So you are given two elements of a horizontal circular curve - Radius, and Intersection Angle.

To Find Degrees, Length, Tangent Length, External Ordinate, Middle Ordinate, and Long Chord.

Solution Code in Python:

import math
R = float(input('Radius, R: '))
u = input('units ')
D = 5729.57 / R
print('Degree of Curve, D = 5729.57/R = ', D,'degrees')
a = float(input('Intersection Angle(degrees) , I: '))
i = math.radians(a)
T = R*(math.tan(i/2))
print('Tangent Length, T= R*tan(I/2) =', T, u)
L = float(a*100/D)
print('Length of the Curve, L = I*100/D = ', L,  u)
e = R*(1/math.cos(i/2)-1)
print('External Distant, E = R*(Sec(I/2) - 1) = ', e, u)
M = R*(1-math.cos(i/2))
print('Middle Ordinate, M = R*(1 - cos(I/2)) = ', M, u)
Lc = 2*R*math.sin(i/2)
print(f'Long Chords, Lc = 2R*Sin(I/2) = ', Lc, u)

I hope it works for you!

Thanks!

Draw an Octagon using Python's Turtle Module (Computer Programming Language) - Code Sheet

2020-09-11T02:38:00.010-07:00

Hi,

I am sharing the code sheet in Python language that you can copy and paste, as it is, onto the interfaces such as Pycharm and Intellij to get the Octagon in yellow colour. If you have any doubts, please let me know in the comment box.

import turtle
sanju = turtle.Turtle()
sanju.color("red", "yellow")
sanju.begin_fill()
sanju.forward(100)
sanju.left(45)
sanju.forward(100)
sanju.left(45)
sanju.forward(100)
sanju.left(45)
sanju.forward(100)
sanju.left(45)
sanju.forward(100)
sanju.left(45)
sanju.forward(100)
sanju.left(45)
sanju.forward(100)
sanju.left(45)
sanju.forward(100)
sanju.left(45)
sanju.end_fill()
turtle.done()

Solved Example-Distance of a Point from a Line, whose end Co-ordinates are given.

2017-11-22T20:54:00.001-08:00

Hi,

Problem:
The X and Y coordinates(in meters) of station Shore are 246.87 and 659.46 respectively, and those for station Rock are 437.85 and 973.48, respectively. The azimuth, bearing, and length of the line connecting station Shore to station Rock are 31d,18 m, 24 s, N31 d18 m 24s E, and 367.540 m, respectively.
What is the perpendicular distance of a point from the line if the X and Y coordinates of the point are 414.278 and 959.083, respectively?

Note:

Thanks for visiting!
Let me know if you have any doubts about the solution, I will make it easy for you.

solved Example - Find the elevations at full and half stations along sag curve

2017-11-07T17:48:00.002-08:00

Problem:
A -2.8% grade line meets a +3.6% grade line at station 125+00. Elevation=1631.04 ft. Determine the elevation of all full and half stations if a 650-ft curve is to be used.

solution:

Solution of vertical curve length, that passes through a fixed point elevation - solved example.

2017-11-07T17:21:00.002-08:00

Problem:
A -4% downgrade intersects a +3% upgrade at elevation 120.00 ft at station 95 + 00. it is desired to pass a vertical curve through a point of elevation 128.00 ft at station 96 + 00. determine the curve length required.

solution:

Solved - Vertical parabolic curve - PVI, PVC and PVT and Elevations at different stations along Curve

2017-04-18T04:04:00.001-07:00

Hi,

Here is the example which shows you how to solve for the vertical transition curve elevation.

Problem: A 3% grade intersects a -2% grade at station 4+350m with an elevation of 190.5m. Given that a 250m symmetrical parabolic curve highway is utilized, determine:

elevation in meters at station 4+240
elevation in meters at station 4+260
elevation in meters at station 4+280
elevation in meters at station 4+300

Vertical Parabolic curve - PVI, PVC and PVT

Solution: Please refer the images below.

Parabolic vertical curve - elevation at stations along curve

thanks!

Curves - Degree (Chord and Arc Definition) - L,T,E,M,Lc,PT,, PC

2017-01-06T07:45:00.000-08:00

Hi,
If you are given with the degree, angle of intersection and Station of PI, how to find the L(length of curve), T(Tangent length), E(External ordinate), M, Lc(Length of chord), PT(Point of tangency) station, PC(Point of Curvature) station. The formulae and example is given in the following images.

Example has three parts, each part is a different question in itself.

Thanks!

How to Draw Contours using Judgement and Free Hand Method

2016-12-22T21:50:00.000-08:00

Hi,

There are other method of contouring like the arithmetic estimation, but for less accurate but quick draw, one can use their fine judgement and free hand technique to draw the contours for the given elevation points.

In the following example, the control points are already drawn. The square patterned control points' elevations are shown, one has to use the fine judgement to draw the contour lines. See how it is done, all you have to do is to judge the contour line's placement from the given elevations.

Look at the nearest control point elevations. If the nearby elevation is higher, then the terrain is rising towards it, if it is lower, terrain must have a downward gradient.

Definitely the higher contour must lie towards the rising terrain and a contour with the lower elevation must lie towards the downward gradient.

Drawing Contour Lines free hand with fine judgement

Thanks for visit!

Elevation of Intermediate Stations in Leveling - Height of Instrument Method

2016-12-22T21:35:00.001-08:00

Hi,

In a profile leveling process, in between two turning points(TPs), there are many intermediate stations that we take readings to find out the elevations of the those stations.

These readings can be taken using a level, a theodolite or a total stations. Problem is that how to find out the elevation of those stations.

Using a bench mark and its given elevation it can be learned from the following example.

The method used is generally known as the Height of the Instrument method. If you have any doubt please let me know in the comment box.

Height of the Instrument Method - Profile leveling - Elevation of intermediate stations.

Thanks for visit!

Closed Traverse - How to find out the Bearings of Traverse Lines

2016-12-22T21:28:00.001-08:00

Hi,
Let us learn to find out the bearings of the lines of a closed traverse with the help of the following example. such problems occur in the Compass traverse or Theodolite Traversing.

Example
you are given a closed traverse with four sides, three of its interior angles A, B and D are given. Find out the bearings of the four lines if the bearing of the line AB is given.

Solutions:

closed traverse- Compass survey - finding out Bearings of lines.

Thanks for visit!

Relevant books:

Error and Correction in a Closed Traverse by Compass Surveying.

2016-10-07T03:08:00.004-07:00

Hi,

A closed traverse constructed after doing a compass survey can be checked for error by a simple formula.

Working with Interior Angles

As per the geometry, in a closed traverse with 'n' number of sides the total sum of the interior angles = (2*n - 4) * 90 degrees.

Example:

Consider a pentagon with five sides and five number of interior angles A, B, C, D and E.

n = 5 (no. of sides)

Sum of the interior angles = (2*n - 4) *90
= (2*5 - 4) *90
= 540 degrees.

If it was a hexagon,

then n = 6
and sum of interior angles would be
= (2*6 - 4)* 90 = 720 degrees

Apply this check to the closed traverse at hand and see the error.

Error =
Sum of the given (actual) interior angles - Theoretical Sum =

Sum of the given (actual) interior angles - (2*n - 4)*90

Correction = - Error.

Generally the error is equally divided among the interior angles of the traverse.

Hence, correction for each angle = - (Error) / n,

where n is the number of sides of the closed traverse.

Working with Exterior Angles

If the exterior angles are given, then the total sum of the exterior angles = (2n + 4) * 90
Remember, an exterior angle = 360 - interior angle.
For example, exterior angle at any station A = 360 - Int. angle A.

Calculate the Error, E = Total Sum of exterior angle - (2n + 4)*90
Correction = -E
Divide the correction equally for each angle = -E/n.

Thank You!

Happy New Year to Surveyors- Why no new posts?

2016-01-02T20:53:00.000-08:00

Hi,

Its been a long time since I came here to write a blog post. I feel that if I stay away a little longer I will get kind of disconnected. Its a new year, and like everyone else, I have new hopes and aspirations.

To keep the connection with my lovely readers is one of my resolution, and it feels really awesome while I write this post. This blog has reached more than 1,50,000 views and is among the top viewed blogs that I write here. As you can see in the side links, there are around fifteen other blogs that I write, and only few of them are competitors of this blog.

One reason that I am not able to write here new posts, is that I am no more a Surveying teacher, and I am out of ideas and topics to write anything about. However I want to write here new posts, and as soon as I get the new ideas I will post here. If you can suggest me anything, please leave a comment, and I will see what I can do.

Thanks! and once again a very happy new year to you.

Survey camp is not just a technical training.

2015-07-09T03:03:00.000-07:00

Hi,

This was long time ago when I posted here my last post, and if you have subscribed to my blog then you might be angry with me. Well, I am sorry, and hey! this is a technical blog, so better I come to the business at hand. I have nothing much technical to write here today, I want to ask a simple question from my readers, do you think that survey camp is more than just a technical training?

If yes, then please do comment about the experiences that you had in your weeks of togetherness with you batch-mates. Generally the camps are held at some wild terrain, having numbers of small or big hills and valleys. This is necessary because one has to learn to find out the contours and thereby draw them on the sheets.

Various streams or roads are to be accurately located and thereby drawn on the sheet. Theodolite and plane tables are the two most necessary instruments that are to be employed, right? But, there is something more important than all these things.

What is that? Its the team work and mutual understanding. The co-operation is highly required, and if its not there, it has to be built here. You might love or hate someone in your team, but at the best you have to do your work, and make up to each other for any differences. This is the reason that Survey camp is not merely a technical training but a personality building training as well.

If you are to take a reading with Theodolite, there has to be someone standing with the graduation staff at the target. Similarly, if you have to draw a line on your sheet in the plane table, one of your team member has to be there at the target. Same goes with the chaining or even in compass survey,

What do you say?

Please share your views!

Thank you!

Surveying- II (N.S.) B.Tech. 4th Sem Examination (CE-224) - HPTU- 2014

2014-08-04T02:31:00.004-07:00

Please find here the question paper set by HPTU for B.Tech. 4th Semester Examination June 2014, for Surveying-II (CE-224).

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B.Tech. 4th Semester Examination

Surveying -II (N.S.)

CE-224

Time: 3 Hours Max. Marks: 100
The candidates shall limit their answer precisely within the answer book (40 pages) issued to them and no supplementary/continuation sheet will be issued.
Note: Attempt five questions in all selecting one question from each section A, B, C and D and all subparts of Section E are compulsory.

Section - A

1. (a) Two parallel railway lines are to be connected by a reverse curve. If the lines are 10 m apart, the maximum distance between tangent points measured parallel to the straight is 50 m, find:

(a) radius R if R1=R2=R

(b) radius R if R1= 50m. Also caculate the length of both curves. (14)

(b) Discuss the characteristics of a transition curve by the method of tangential method. (6)

2. Describe the weight of quantities. How weight of different quantities are allocated? Discuss various laws of weights. (20)

Section - B

3. (a) A base line was measured with steel tape which was exactly 30 m at 20 degree Celsius at a pull of 100 N. The measured length was 1500.00 m. If the temperature during measurement was 28 degrees Celsius and pull applied was 150 N, determine correct length of line if cross section area of tape = 2.5 mm^2, coefficient of expansion 3.5*10^(-6) per degree Celsius. Modulus of elasticity = 2.1 * 10^3 N/mm^2. (15)

(b) Differentiate between triangulation & trilateration. (5)

4. Two triangulation stations A & B 60 km above having elevations of 265 m and 385 m respectively, the intervening ground may be assumed to have a uniform elevation of 220 m. Find the minimum height of signal at B so that the line of sight may not pass neat the ground less than 3 m. (20)

Section - C

5. Draw the expression to determine the height of the object when the two instruments stations are not in the same vertical plane. (20)

6. Following observations were made in trignometric levelling:

Observed altitude = 3 Degree 10 minute 49 seconds.

Height of instrument = 1.24 m

Height of signal = 5.32 m

Horizontal distance = 4935 m

Coefficient of refraction = 0.07

Rsinj" = 30.88m

Correct the observed altitude for the height of signal, refraction and curvature. (20).

Section - D

7. Explain in detail the basic geometric characteristics of aerial photographs. (20)

8. (a) A rectangular agricultural field measures 8.65 cm long & 5.13 cm wide on a vertical photograph having scale of 1:20,000. Find are of field. (6)

(b) What is the significance of equation of time? How do we calculate the local time at a location.? (14)

Section - E

9. Attempt all parts:

(a) If the first chord gradient is 0.16, calculate the gradient of fourth chord.

(b) What is the basic criteria for the design of transition curves?

(c) Differentiate between triangulation and traversing.

(d) Define "extension of base line".

(e) How do you account correction for curvature of earth in trigonometric levelling?

(f) What is axis-signal correction?

(g) Define "Tilt displacement" in photogrammetry.

(h) What is "station adjustment"?

(i) Explain most probable value. (2*10 = 20)

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Thanks for your kind visit!

Error due to Refraction and Curvature

2014-06-23T08:29:00.001-07:00

Hi,

Finally, today I thought to write about this particular topic, which is important to study when we are talking about Geodetic Surveying.

As we know, in Geodetic Surveying we have to consider the error due to the curvature of the earth and the refraction too. Reason is because a larger area is surveyed in Geodetic Surveying, more than about 256 km2. In such large areas, the error due to curvature of the earth has to be considered to calculate the linear distances and also in case of the angular measurements.

We have to consider the refraction error too, because here we are dealing with the large distances and in order to get the correct results we have to apply these correction.

What is the Error due to Curvature?

To understand this simple concept of error due to curvature of the earth, first you have to understand the shape of the earth and the methods and instruments which we employ for calculating these distances.

When we do leveling with Theodolite or Autolevel, the line of sight first is set horizontal. Then we measure the vertical angle to the target and by applying some trigonometrical formulae we can calculate the vertical distance of the target from that horizontal line.

Error due to curvature comes into play, because in the cases of long distances, the horizontal line and level line do not coincide. Level line is a curved line, parallel to the level surface, but the horizontal lines goes straight.

This means that the vertical distance of that target from the level line is going to be larger than the distance which we calculate from the horizontal line. Please refer the figure given above, the amount of correction depends upon the magnitude of the horizontal distance between the target and the instrument station.

What is Error due to Refraction?

Error to refraction can be understood easily once you understand the phenomenon which takes place when light passes from one density system to another density system. Refraction is nothing but the phenomenon by which when light travels from a denser media to the lighter media, it deflects away from the normal to the plane of the media.

Phenomenon occurs vice-versa when light travels from lighter media to denser media. This phenomenon has to be considered in the calculation of the distances in case of Geodetic Surveying. Suppose a man is taking the observation of the top of a hill from a point, which is at a considerable down far vertical distance from it to change the density of the air.

We know that density of air decreases with the height, this will effect your line of sight. The line of sight of a person who is taking observation to a point at a quite higher distance, will be a curved path, because light will continuously change its direction due to the continuous change in the density of the air.

Imporant question to ask is, how does it effect our observations? Well, the observed angle will be to high in case of taking the observation of an elevated object and the observed angle will be small in case of taking observations to an object in depressions.

Correction for the Error due to Curvature and Refraction:

There are a numbers of textbooks, which explains the procedure to calculate the correction for the refraction and curvature.

Formulae:

Curvature correction, Cc = - 0.07849.D^2 meter

Refraction Correction, Cr = 0.01121.D^2 meter

Combined Correction C = Cc+Cr= -0.06728. D^2 meter; here D is in kilometer

Thanks for your kind visit!

Training Program on Total Station

2014-03-07T19:37:00.002-08:00

Hi dear,
Yesterday, I read a notice from the HOD(Head of Department) which informed about a training program on the working and using the "Total Station".

This program is going to be held at our own institute and this will be free for the students and teachers of the institute. I have written blogs about almost every topic on the basics of Surveying in this blog and Total station is a topic which I think is still un-touched here.

So, hopefully soon I will post about Total Station and if that comes out to be useful for you too, I will be most happy.

Total station is used where we need fast and very accurate results in terms of the observations which we have to take to check the leveling and distances of the points. Specifically in case of the tunneling and bridge constructions, we have to be very accurate with our measurements.

Any small error can result in the failure of the project and may result in the loss of a huge amount of money. In that manner, Total Station is a requirement of every Civil engineer working in such projects.
This instrument is a little costly but still people who can afford it, will surely use it instead of any other instrument.

Thanks for your visit!

Take care!

How to find out the area using Planimeter

2014-02-22T22:00:00.002-08:00

Hi,

Planimeter is a Surveying instrument which can be used to find out the area of a map or plan. A Swiss mathematician Jacob Amsler Laffon built first modern planimeter in 1854. Many developments followed Amsler's famous Planimeter including the electronic planimeter.

A Polar Planimeter (source: wikipedia)

We have three mechanical types of Planimeters:

Polar
Linear
Hatchet Planimeter

All Planimeter work on the same principle.

There is a linkage, at one end is a pointer and the other is fixed for a polar planimeter and is restricted for a linear.The pointer is traced along the perimeter of the area of the shape is indicated on a scale.

There is a wheel attached to planimeter which rolls when the movement of the pointer is perpendicular to the axis of the wheel so, this movement is recorded.

It will skid when the movement of the wheel is parallel to the axis so, this movement is ignored.

Linear Planimeter (Source : Wikipedia)

That means that planimeter measures the distance which is traveled by the rolling of the wheel. Area of the shape is proportional to the nos. of turns through which the measuring wheel turns.

The area calculations can be proved by using Green's Theorem.

Please visit wikipedia for detailed study.

In order to find out the area, all you have to do is to trace the perimeter of the area on the map, and note down the reading.

To get more accurate results one should be skilled in tracing the exact perimeter of the shape.
You can convert the area to the field area using the scale of the map.
These days digital planimeters are in the market which are more easy to use.

Thanks for visit!

Classifications of Theodolites

2014-01-20T07:03:00.001-08:00

Hello there,

Theodolite is one of the basic instrument which has many uses including traversing. Theodolite is broadly classified into two categories:

Transit Theodolite In this type of Theodolite, line of sight can be reversed by revolving the telescope 180 degrees along the vertical plane.

Non-Transit Theodolite In this type of Theodolite, the line of sight can not be revolved in the vertical plane.

There are other classifications of the Theodolite:

Vernier Theodolites.
Micro-meter Theodolites.

Size of Theodolite: This is defined by the diameter of the graduated circle of the lower plate. Common sizes are 8 cm to 12 cm while 14 cm to 25 cm are used for triangulation work or you can say for more precise works.

EDM

Main parts of a transit vernier Theodolite are

Leveling head
lower circular plate
Upper plate
Telescope
Vertical circle

There are some fundamental lines of Transit Theodolite:

Vertical axis
Horizontal axis or Trunion axis
Axis of the altitude bubble or Azimuthal axis
Line of collimation
Axis of the plate bubble
Axis of striding level if present.

Thanks for kind visit!

Surveying notes for GATE and PSUs exams. - Part 11

2014-01-07T23:16:00.001-08:00

Hello there,

The following facts are taken from many references, mainly from the book titled "Civil Engineering objectives" by S P Gupta and S P Gupta.

Bowditch method has used the assumptions: Errors in linear measurements are proportional to under root of L.; Correction to latitude or departure of any side = Total error in L(or D) * (Length of that side/ Perimeter of traverse).
To determine the length of a bridge proposed to be built across a wide river, the triangulation method of surveying will be preferred over tacheometry, chain surveying.
Heliograph is a type of sun signal used in triangulation work.
A 100 m tape is held 1 m out of line. The true length will be 99.995 m
When the line of collimation is not perpendicular to the horizontal axis taking face-left and face-right observations reduces the error.
It is not necessary to do the exact centering of plane table to do the small scale surveys.
Saddle line is also known as ridge line or valley line.
Line of drainage basin is the line which passes through ridges and saddles setting up a domain.
Longitude of a place is measured by wireless time signal and transportation of chronometers.
In tilting level the vertical axis is not perpendicular to the line of collimation.
Inverted staff readings are taken for the points above the line of collimation.
Reciprocal levelling eliminates the error due to inclined line of collimation also.

Thanks for visit!

Surveying notes for GATE, PSUs - Part 10

2014-01-06T22:00:00.001-08:00

Hello there,
How have you been? Here is 10th part of one liners for the preparation of the GATE and PSUs.

All information is learned through books and practical exercises.

To find the R.L. of a roof slab of a building, staff readings were taken from a particular set-up of the levelling instrument. The readings were 1.050 m with staff on the benchmark and 2.300 m with staff below the roof slab and held inverted. Taking the R.L. of the B.M. as 135.150 m, the R.L. of the roof slab will be 138.500 m.
Operations involved in a spire test are : 1) Sight a well-defined high point on a high building 2) Clamp horizontal plates 3) Depress the telescope and sight a point on the ground nearer to the instrument 4) Change face and repeat the procedure.
Accurate centering in plane table surveying is necessary for large scale maps.
Exact orientation is more important than accurate centering for small scale maps.
The intersection method of plane table surveying is particularly employed for inaccessible points.
Plane table survey is useful for open country with good inter-visibility.
Simpson's method estimates best the area of an irregular and curved boundary.
In a closed traverse, the sum of south latitudes exceeds the sum of north latitudes and the sum of east departures exceeds the sum of west departures. The closing line will lie in N-W quadrant.
In reciprocal levelling, the difference in elevation of two points is calculated by taking the average of the differences obtained by taking measurements from two different instrument settings, one at near to first station and second at near to second station.
A lemniscate curve between the tangents is transitional throughout,the polar deflection angle of its apex is equal to A/6.

Other parts :

part 4 : http://surveying2012.blogspot.com/2013/12/gate-psus-surveying-one-liners.html
part 5: http://surveying2012.blogspot.com/2013/12/surveying-notes-for-gate-psus-part-5.html
part 6: http://surveying2012.blogspot.com/2014/01/surveying-notes-for-gate-psus-part-6.html
part 7 : http://surveying2012.blogspot.com/2014/01/surveying-notes-for-gate-psus-part-7.html
part 8 : http://surveying2012.blogspot.com/2014/01/surveying-notes-for-gate-psus-part-8.html
part 9 : http://surveying2012.blogspot.com/2014/01/surveying-notes-for-gate-psus-part-9.html

Thanks for visit!

Surveying notes for GATE, PSUs - Part 9

2014-01-04T22:48:00.000-08:00

Hello there,
How have you been? Here is 9th part of one liners for the preparation of the GATE and PSUs.

All information is learned through books and practical exercises.

If quantity A has a weight of 3, then the weight of A/3 will be 27.
In a parabolic vertical curve, the rising grade g1= +0.80% and the falling grade g2= -0.70%. The rate of change of grade is 0.05 per chain, then the length of the vertical curve is 30 chains.
While measuring horizontal angles by the method of repetition with a theodolite, readings are taken on both the vernier. Error due to imperfect graduations will be eliminated.
An angle-measuring instrument reading up to one-sixth of a degree on the main scale is equipped with a vernier having 19 main scale divisions divided into 20 parts. The correct least count for the instrument is 30 seconds.
If it is required to produce the plan of a small area under the magnetic influence, plane table survey will be the best choice.
Clinometer- An angle measuring instrument.
Tellurometer - microwave instrument
Pantograph- Plan enlarging instrument
Ghat tracer - Grading finding instrument.
Offsets are lateral measurements made with respect to main survey line.

Other parts :

Surveying notes for GATE, PSUs - Part 8

2014-01-03T19:41:00.001-08:00

Hello there,
How have you been? Here is 8th part of one liners for the preparation of the GATE and PSUs.

A curve tangential to four straight lines and consisting of arcs of different radii is known as three centred compound curve.
The length of the tangent of a curve of radius R and angle of deflection D is given by R.tan(D/2).
The length of the long chord of a simple circular curve of radius R and angle of deflection D is 2R.sin(D/2).
Setting out a curve by two Theodolite method does not require linear measurements.
If r is the radius of curvature at any point of a transition curve and l is the distance from the beginning of the transition curve to that point, then for ideal transition l is inversely proportional to r.
In a reverse curve, the super-elevation provided at the point of reverse curvature is zero.
Total angle of deflection of a spiral curve is (spiral angle/4).
The shape of vertical curve generally provided is parabolic.
Perpendicular offset from the junction of transition curve and circular curve to the tangent is equal to four times the shift.
If L is the length of transition curve and R is the radius of circular curve, then the shift of the curve is directly proportional to L^2 and inversely proportional to R.
The difference in elevation of points between a vertical and a tangent is directly proportional to the square of its horizontal distance from the point of tangency.
Shift bisects the transition curve and transition curve bisects the shift.
The maximum value of centrifugal ratio on roads and railways respectively are 1/4 and 1/8.
Agonic line is the line joining points having zero declination.
For a circumpolar star, declination must be more than co-latitude.
For a star at its upper transit, the local sidereal time is equal to R.A. of the star.
Sidereal year(SY) is greater than Tropical year(TY).
The limiting minimum value of declination of a circumpolar star having latitude 40 degrees North is (90-40) = 50 degrees.

All information is learned through books and practical exercises.

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Surveying notes for GATE, PSUs - Part 7

2014-01-02T20:09:00.002-08:00

Hello there,
How have you been? Here is 7th part of one liners for the preparation of the GATE and PSUs.

Two point problem and three problems are methods of orientation and resection.
Resection by two point problem requires more labor than by three point problem.
Methods used to locate the plane table station are resection and traversing.
After fixing the plane table to the tripod, the main operations which are needed at each plane table station are levelling, centering and orientation respectively.
Bowditch rule is applied to a closed traverse for adjustment of closing error.
If in a closed traverse, sum of south latitudes is more than sum of north latitudes and also sum of east departures is more than west departures, the bearing of closing line is in NW quadrant.
The angle between prolongation of preceding line and the forward line of a traverse is called deflection angle.
Transit rule of adjusting the consecutive co-ordinates of a traverse is used where angular measurements are more accurate than linear measurements.
While theodolite traversing, angles are measured from at least two stations to locate a point which is at a far distance.
Subtense bar is an instrument used fr measurement of horizontal distances in undulated areas.
Horizontal distances obtained by tacheometric observations do not require slope and tension corrections.
There are three horizontal corss hairs- in a stadia diaphragms.
In movable hair method, the intercept on leveling staff is kept constant and stadia hair interval is variable.
In fixed hair method the intercept on leveling staff is variable and stadia hair interval is fixed.
In tangential hair method the stadia hairs are not used.
The angle subtended by the long chord of a simple circular curve at its centre is equal to angle of deflection.

All information is learned through books and practical exercises.

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