I have drawn up a spreadsheet explaining how to do the basic calculatuions for the rise and fall method of leveling my surveying students who. Bench Marks are no longer maintained by the Ordnance Survey (although Fundamental (F)BMs instrument/level (IH) from which all other levels are calculated. Procedure: Set up the leveling instrument at Level position 1. Hold the staff on the Datum (RL+50 m) and take a reading. Move the staff to A and take a reading. Move the staff to B and take a reading. Move the staff to C and take a reading. Move the staff to D and take a reading.Procedure · Rise & Fall · Arithmetic Checks · Height of. Collimation.
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The level line of sight is 2.
Levelling Calculations made easy - Rise and Fall Method
A typical procedure for a linear track of levels from a levelling survey calculation datum is as follows.
Set up the instrument within metres yards of a point of known or assumed elevation. A rod or staff is held vertical on that point and the instrument is used manually or automatically to read the rod scale.
This gives the height of the instrument above the starting backsight point and allows the height of the instrument H. The rod is then held on an unknown point and a reading is taken in the same manner, allowing the elevation of the new foresight point to be computed.
The procedure is repeated until the destination point is reached. levelling survey calculation
It levelling survey calculation usual practice to perform either a complete loop back to the starting point or else close the traverse on a second point whose elevation is already known. The closure check guards against blunders in the levelling survey calculation, and allows residual error to be distributed in the most likely manner among the stations.
Some instruments provide three crosshairs which allow stadia measurement of the foresight and backsight distances. These also allow use of the average of the three readings 3-wire leveling as a check against blunders and for averaging out the error of interpolation between marks on the rod scale.
8. TOPOGRAPHICAL SURVEYS - DIRECT LEVELLING
The two main types of levelling are single-levelling as already described, and double-levelling Double-rodding. In double-levelling, a surveyor takes levelling survey calculation foresights and two backsights and makes sure the difference between the foresights and the difference between the backsights are equal, thereby reducing the amount of error.
There may be obstructions or large changes of levelling survey calculation between the endpoints. In these situations, extra setups are needed.
8. Topographical Surveys - Direct Levelling
Turning is a term used when referring to levelling survey calculation the level to take an elevation shot from a different location. To "turn" the level, one must first take a reading and record the elevation of the point the rod is located on.
While the rod is levelling survey calculation kept in exactly the same location, the level is moved to a new location where the rod is still visible. A reading is taken from the new location of the level and the height difference is used to find the new elevation of the level gun.
This is repeated until the series of measurements is completed. The level must be horizontal to get a valid measurement. Using step 8 as a levelling survey calculation, enter all measurements in a table and calculate the results as shown in the example below.
You will find that point B is 2. Even if you are careful, you may levelling survey calculation make mistakes when you make your arithmetic calculations from the table.
Software - Field Book Data to Reduced Level Conversion
To reduce this kind of error, add two additional columns to your table that will make checking your calculations easy. These columns will also help you to calculate the elevation of each turning pointand to on the elevation of point Levelling survey calculation more carefully.
Example Differential levelling with several turning points Making topographical surveys by straight open traverses