Dear All,
Please could any one suggest the best possible way to close the traverse with least error.
we have used Prism over Tribatch but still could not Achive the Good Result.
The total Length of Travese is 5Kms, and we have 9 Intermediate Stations.We have tried with four Different Makes of Total Stations
The least we could Achive was +130mm Error in Easting and +95mm Error in Northing and 90 mm in Elevation.
Thanking You,
Srirama.Vattamwar
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Replies
Dear All,
Thank you for the valuable Information and suggestions we could finally close this job. The client satisfied with the latest result. In the latest Job we have taken closer stations, max distance between station was 280mts and the weather was nice and cool, We have changed the tribatch as well.
At closing we got +26mm E and +34mm N and the elevation was 105mm. So we have used an 28X sOKKIA AUTOLEVEL to close the Vertical Error and we ended with 15mm.
Once again Thank you all for giving me your valuable time and needful information.
Thanks & Regards,
Srirama. Vattamwar
I agree with Keith and Leopoldo - Unadjusted tribrachs, incorrect prism constants, and loose tripods are often overlooked as a source of error. Good luck with this puzzle!
Hi Srirama,
Does your traverse have large differentials in elevations?
Some years ago I ran a traverse from a trig beacon to a previously coordinated traverse station near a road in hilly terrain. The difference in elevation between begin and end point I cannot recall, but it was substantial - a couple of hundred meters.
In South Africa we generally apply a scale enlargement and sea level (elevation) correction to each of the traverse leg distance readings, the factors being determined by meaning the Easting coordinates and elevation for the entire distance of the traverse.
In this instance I found the mis-closure was pretty bad, but after puzzling it out I decided to apply separate sea level corrections to each traverse leg based on the elevations of each traverse station pair. This worked out very well and I got a very good closure.
Hello Srirama,
make sure that your tribrach is calibrated, check your prism constant and take backsights and foresights in 3 readings to take the final mean horizontal reading.
for elevation you must run a levelling and use double set up method.
use "starnet" to compute both traverse and level
hope it helps..
Hello Srirama,
Still thinking about your survey...in the mean time you could refer to this:
Surveying Measurement and Their Analysis by R.B.Buckner
ISBN-10: 0910845115 | ISBN-13: 9780910845113
Make sure your tribracs are in adjustment. Do not break your setup but move the instrument into the foresight tribrac, Double your angles turn direct and reverse. Be sure your EDM in the gun is adjusted and also your vertical angle.
Dear Syrama: use 3 tribrach , read 2 faces, and use umbrella.
Dear scotte D. Warner,
Thank you for responding my query,Here are the details of the Job.
We have considered azimuth coordinates
station Code(starting Point) A1: Easting: 10,000, Northing:20,000 Elevation: 100 mts
Instrument Used: Pentax set 3030R
Accuracy of the Instrument: 3"
Date Instrument Calibrated recently: 13/09/2012
Time duration to close the traverse: 8 Hours
Temperature: Min: 30 degree Celsius,Max 33 Degree Celsius
Reflector Used: Prism.( Prism was placed on Tribatch at each station), for taking back site only the top part of tribatch and upper portion of Total station leaving the base plate on tripod was moved.
Total Intermitent Stations: 13 Stations ( minimum distance between each station was 300mts and the maximum was 620 mts (only between two stations).
Closing co-ordinates: Easting:10000.131, Northing:19999.905, Elevation:99.819.
Topography: Plain.
Thanks & Regards
Srirama Vattamwar
Scott D. Warner, R.L.S. said:
Dear Paul,
Thank you for responding my query,Here are the details of the Job.
We have considered azimuth coordinates
station Code(starting Point) A1: Easting: 10,000, Northing:20,000 Elevation: 100 mts
Instrument Used: Pentax set 3030R
Accuracy of the Instrument: 3"
Date Instrument Calibrated recently: 13/09/2012
Time duration to close the traverse: 8 Hours
Temperature: Min: 30 degree Celsius,Max 33 Degree Celsius
Reflector Used: Prism.( Prism was placed on Tribatch at each station), for taking back site only the top part of tribatch and upper portion of Total station leaving the base plate on tripod was moved.
Total Intermitent Stations: 13 Stations ( minimum distance between each station was 300mts and the maximum was 620 mts (only between two stations).
Closing co-ordinates: Easting:10000.131, Northing:19999.905, Elevation:99.819.
Topography: Plain.
Thanks & Regards
Srirama Vattamwar
Paul Quagge said:
This could be a scale problem or a problem with the beginning or ending control points. What is the coordinate grid system? Are you applying grid and elevation scale factors? How were the beginning and closing points established? How good is the beginning azimuth or direction control?
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