Reference no: EM131556798
Land & Construction Surveying
Component 1: Resit work -
Task
Explain how a surveyor's automatic level is used to determine the heights of points. You should include a description of how to test such an instrument and the industry standard method of recording and calculating the heights.
Two control stations, STN A and STN B, have been heighted via a level run starting and finishing at an Ordnance Survey Bench Mark. The observations can be obtained from the supplied Excel spreadsheet as directed below. Reduce the levels to obtain final heights for the control points showing all the normal calculation checks. Comment on the precision of the results.
Data
Level observation data for this assignment are obtained from the Excel spreadsheet.
Download the file and open in Excel - YOU MUST ENABLE MACROS when opening in Excel. Enter YOUR student number in the cell indicated and click on the Print button. This should give you a print preview from which you can print the data.
Please note that you must give your own student number. Any submission with data generated from another number will not be marked.
Submission Present your work neatly in a professional manner. When writing technical reports it is expected to use sections with appropriate sub-headings. Use the 3rd person indefinite - that is to say do not state "I / we set up the instrument" but rather "The instrument was set up".
The complete portfolio must be submitted within Moodle before or on the date given above. Work received up to 24 hours late will be subject to a penalty of 5%, work submitted after this time will receive an automatic mark of 0% unless extenuating circumstances have been sought and granted.
Component 2: Resit work
Task A - Co-ordinates
There are 4 brackets on the vertical face of a wall to which a banner is to be fixed. It is required to know the distances between these brackets together with their height so that the banner and fixing system can be manufactured and to ensure that it is visible from certain locations.
Observations have been taken to the brackets with a reflectorless total station set up over a point (STNA). Horizontal and vertical angles with slope distances have been observed to the 4 brackets.
Using the data supplied, calculate the heights of the brackets and the distances AAA-BBB, BBBCCC, CCC-DDD, DDD-AAA.
Data
Observation data for this assignment are obtained from the Excel spreadsheet and include Level observations, Horizontal and Vertical Angles and slope distances.
Download the file and open in Excel - you must enable macros. Enter YOUR student number in the cell indicated and click on the Print button. This should give you a print preview from which you can print the data.
Please note that you must give your own student number. Any submission with data generated from another number will not be marked.
Method
1. Reduce the horizontal angle observations to give a mean set of angles.
2. Reduce the vertical angle observations to give a mean set of angles
3. Calculate the mean slope distance to each bracket
4. Reduce the mean slope distances to give horizontal distance and difference in height using the respective vertical angle.
5. Use the height of STNA, height of Instrument and difference in height from the vertical angle to calculate the height of each bracket.
6. Define a coordinate system by allocating STNA an arbitrary set of coordinates (E, N) and assume bearing for the direction to the RO.
7. Calculate the bearing in this coordinate system to each bracket and using the horizontal distance, determine the coordinates of each.
8. Using the coordinates calculate the distance between the points as required.
9. Abstract the distance and heights. 10. Give an estimate of the precision of these values and discuss improvements.
Submission Present your work neatly in a professional manner. When writing technical reports it is expected to use sections with appropriate sub-headings. Use the 3rd person indefinite - that is to say do not state "I / we set up the instrument" but rather "The instrument was set up".
Indicate how calculations have been performed, including formulae, rather than just quote the result so that any mistakes can be located. Spreadsheets, such as Microsoft Excel, developed by yourself may be used but include a print out of the formulae.
The complete portfolio must be submitted to Moodle before or on the date given above. Work received up to 24 hours late will be subject to a penalty of 5%, work submitted after this time will receive an automatic mark of 0% unless extenuating circumstances have been sought and granted
Component 3: Resit work
Task A : Traverse
|
STN
|
deg
|
mins
|
secs
|
dist
|
|
A
|
64
|
41
|
59
|
65.980
|
|
B
|
60
|
36
|
11
|
45.348
|
|
C
|
67
|
16
|
23
|
23.981
|
|
D
|
167
|
25
|
47
|
70.477
|
|
A
|
408030.350 East
|
90603.560 North
|
Opening Bearing: the back bearing from B to A is given as:
Your student number/14400, then convert to DMS
For example: student number: 1456789 Divide by 14400 = 101.1659o = 101o09'57"
MY STUDENT NUMBER - 1611890
(i) compute the traverse to partial co-ordinates and determine the linear misclosure
(ii) identify the gross error and recalculate, and find the difference this gross error had on the linear misclosure
Hint - it will be advisable to draw the traverse diagram so that you get the angles and distances in the right order. Remember, you are looking for a misclosure (at the partial coordinate stage) of less than 20mm.
Task B: Setting Out
The setting out of the centres of some bridge supports is to be carried out by total station, using angles and distances.
a. Outline the procedure, indicating the possible errors that could affect the final positions and how the precision of the setting out could be checked and improved?
b. Given the two points have co-ordinates as:
SOP1 384.312mE 370.874mN
SOP2 388.312mE 370.874mN
And the nearest three control points are :
ST09 432.848mE 425.762mN
ST11 456.876mE 346.294mE
ST16 324.548mE 308.333mN
Determine the setting out data for each point from ST09, using ST11 as the RO.
c. As a check, measurements were taken from ST16 using ST11 as RO.
ST16-SOP1 86.503 angle 329-42-26
ST16-SOP2 89.313 angle 331-33-49
What were the discrepancies?
Assessment Criteria:
Submission Item marks
1. Traverse - angles
- Traverse - partial co-ordinates
- Traverse - checks
- Traverse - Bowditch and final co-ordinates
2. Outline of procedure
- A table of setting out data from ST09
- The distances obtained from ST16 to each of the points, and the discrepancy between the calculated and observed points
All submissions are to be INDIVIDUAL. Any evidence in collusion will result in Breach Proceedings, affecting both the originator of the work and the person copying. As all the data is provided, there is no need to share anything with other students.
Attachment:- Assignment Files.rar