Land Surveyor Forum

Replies

• Seeking Employment

  amir shahbaz February 25, 2015 at 9:21pm

  Dear Sir Azam

   new file attached my recomendation for urban planning is please go with total station .if you want accuracy you have old point data like E,N,Elevation then you shift 5 to 10 times your bench mark depends on sight clearence..please search on google for how to use total station you will get many useful material i am now working on topcon 239n 
• Land Surveyor

  Paul Jennings February 25, 2015 at 6:08pm

  Hi Lalith,

      Very interesting.  In southern California we are lucky if we get a small aluminum sign right at the BM.  Many are destroyed every year but we surveyors do are best to perpetuate the elevations when we come accross them and send our data to the appropriate agency.
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  Lalith Senanayake February 25, 2015 at 9:31am

  There is no way to establish cotrole netwok of levels by total station or GPS,
  We have to do precise levelling establish Fundamantle Benchmarks and procceed if we want to establish a network for a country onnectet to Mean sea level.
  But just for local topographic survey establish BMs by levels locally and go ahead.
  • Land Surveyor

    Paul Jennings > Lalith Senanayake February 25, 2015 at 10:24am

    Agree with Lalith,

        For a control network, precise leveling loops.  For a small site or just to perpetuate a BM elevation, closed level loop or MTA with a total station is sufficient. 

        What methods and tools one uses depends on what order of precision is to be achieved and the size of the project.
    • 

      Lalith Senanayake > Paul Jennings February 25, 2015 at 10:51am

      Dear Paul,
      Stil fundamantle Bench Marks established in 1800 could be seen and secured
      hear in Sri Lanka.We can see fenced area giving a warning not to do any blasting around 50m area.
• Government Professional

  Muhammad Azam February 25, 2015 at 2:02am

  Dear all thanks a lot for providing very helpful guidance.
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  Iftikhar Ali February 24, 2015 at 12:31am

  Dear it is very simple.

  Before starting your job you should have at least three known control points in project area.

  You have to select suitable places for BM.

  Take static observation on these BMs (time span as per leg distance).

  Static observation is very common for surveyors.

  Download your static data and process on TBC.  
• Seeking Employment

  amir shahbaz February 23, 2015 at 12:54pm

  your hipper II can be used for bench marking because it is accurate in RTK.i have seen its data sheet now. i think you can understand with this diagram i made for you  
  • Government Professional

    Muhammad Azam > amir shahbaz February 25, 2015 at 2:10am

    Dear Amir sahib,

                         I had seen your diagram but i need the starting point to work i.e what are the considerations and procedures to achieve max. accuracy. 
  • Land Surveyor

    Paul Jennings > amir shahbaz February 23, 2015 at 2:55pm

        If you are trying to establish vertical control off of an existing benchmark and hope to achieve 3rd order or better results, using a total station or level and performing a closed level loop from and to the benchmark is standard practice.  You can adjust the newly established elevations based on your error of closure, if any.

        Even with the newest, latest and greatest RTK equipment, there is elevation error which cannot be substantiated without running a level to check the RTK elevations.  Even post-processed static GPS data will see vertical error.