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

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.

 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?

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.

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

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




      
------------------------------------------------------------------------------------------------------------

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)

-----------------------------------------------------------------------------------------------------------

Thanks for your kind visit!