# Levelling Procedure
The purpose of this document is to describe the process that should be followed in order to correctly perform a precise levelling survey
# Before you Begin
You will require the following before you beging this work process:
# Field Data
• A benchmark height of the starting mark and the height of any known checks, if you are levelling to a known datum and checking points are available
# Software
• Trimble Data Transfer
• Trimble Business Centre
# Hardware
• Trimble DiNi Level
• Level Staff
• Level Tripod
• Change Plate
• Computer with USB-A Cable
• Field Book
# Field Process
# Set up job on the instrument
• Turn on the Trimble DiNi level
• At the main menu screen highlight the Files option and press Enter on the interface. See Figure 1
Figure 1: Main Menu Screen
• Select the Project menu (which is option 1) and press Enter
• Select New project (which is option 2) and press Enter
• Fill out all the fields as required (Project name, operator’s initials, job notes) and press Enter to store. See Figure 2
Figure 2: Job Creation Screen
# Survey Procedure
• At the menu highlight the Survey option and press Enter. See Figure 1
• Select the Line levelling (which is option 2) and press Enter
• This will open up a screen to create a new level run. Ensure that Line is set to New, and that the line number is set to an appropriate number (e.g. 01 for level run 1, 02 for level run 2 etc), and that the measurement method is BF. See Figure 3
Figure 3: The Start Line Levelling Screen
• The next screen allows you to input your starting benchmark. The point number should be set to 01 to minimise errors in TBC later. If more than one level loop is to be performed a convention of 101 and 201 may be more appropriate so there are no duplicate point names between level loops that don’t correspond. The code field is where any helpful descriptions should be stored (e.g. what the actual benchmark name is, or a description). The benchmark height can be either real if the starting height is known, or local if it isn’t. See Figure 4
Figure 4: The Starting Benchmark Screen
• The level is now set up to begin.
TIP
Follow correct levelling procedures during the course of the survey. For example:
- Do not record measurements below 0.3m or above 3.6m
- Maintain equal back sight and foresight distances
- Do not sight further than 60m
- Ensure that all change points are solid and immovable and consistent over the course of a setup
- Check onto other known points if possible
- Close the level loop
- Ensure the digital level is level well within the tolerances of the compensator
• Begin by setting up and levelling the tripod and level as appropriate to back sight to the starting benchmark. Before you measure the screen will look like Figure 5. Note that the B in the top right corner is highlighted to indicate that the next measurement is a backsight measurement. Take the measurement
Figure 5: Initial Backsight Screen
• When the first foresight measurement is to be taken the screen will look like Figure 6. Ensure that increment point number is selected and enter a code/description if required. In the middle box type in the next point number (E.g. 02). After the initial foresight all subsequent ones will increment automatically.
Figure 6: Foresight Screen
• Repeat the above backsight/foresight process until the last foresight measurement is to be taken. Measure the foresight measurement then navigate on the interface to the LEND option to tell the level that the last measurement was to the closing benchmark. See Figure 7. Insert the height of the closing point and press enter. A screen will now display showing the total misclosure (as well as other statistics from the survey)
Figure 7: Ending a Level Loop
# Download and Office
# Data Transfer
• Open Trimble Data Transfer on a PC
• Connect the digital level to the PC via USB
• Connect to the level using the profile for a DiNi Level (USB). The profile should already be created. If it isn’t create a new one by clicking Devices > New> Trimble DiNi (USB) Device. See Figure 8
Figure 8: Connect to Digital Level in Data Transfer
• Click the Add button when connected
• Select the files that you want to copy off the device and choose the location on the PC where you would like to save them. See Figure 9
Figure 9: Copy files from Level
• Click Transfer All to transfer the files
# TBC Processing
• Insert the Trimble dongle and open Trimble Business Centre and create a new project
• Drag and drop the DAT file from the level into TBC to import it. Alternatively click File > Import and follow the prompts to import the file
• This will open the Level Editor. Check that the benchmark heights are correct and rename any duplicate points, or points of interest, as appropriate. See Figure 10
Figure 10: TBC Level Editor
• Click Adjust, in the bottom right corner, if the misclosure is acceptable to adjust and if an adjustment is required. If it is not acceptable then some parts of the level may have to be repeated to identify anywhere an error may be
• Click the small square, in the top left corner, to toggle which level points are to be created in TBC. Toggle the box until all points are checked and press OK
• Save the TBC file. The process is complete